996 gets new life

Hi all, I'm starting a small build / renovation thread for my, new to me, 996 C4 2000 coupe. This is my second 996 and ever since I sold the old one I've missed it. When I had my previous 996 I remember all the things that was worn out or could be improved. 996 are starting to get old so a lot of wear and tear parts usually needs to be replaced by now. This time I bought the cheapest 996 I could find and will use the rest of the 'budget' for replacing worn out parts and upgrades. The goal is to have the car look very much like stock but have it drive better than new. My work list ATM: -New MAF sensor -New crank sensor -New inox silencers (aftermarket but with OEM spec regarding sound). I like engine sound(mechanics), not amplified exhaust sound. ATM there is a aftermarket 'loud' system... -New poly sway bar bushings. The original is disintegrating.The sway bar bushings are easy to access and lube, so poly bushing it will be. -New low temp thermostat 71 degrees -New all aluminium radiators (I live in south of France and it can be rather hot in the summers). I also intend to track the car 1-2 times per year. -Change all liquids and oils. -New plastic exterior fittings, OEM....broken underbody plastics or air diverter doesn't look good. -New LCA bushings, not sure if to go with poly or OEM? not too keen to lube all the bushings if I go with poly. -Inspect and replace broken coil packs -Clean and/or replace spark plugs -New engine mounts -New light weight battery -Center console delete -Remove stereo head unit, amplifier and most speakers. Replace with bluetooth amp (music/radio from phone) with only volume control. -New suspension....not decided which yet. Comfy and adjustable are two criteria. Any suggestions? A lot of work(which I enjoy doing my self) but not that expensive if you hunt for cheap parts. On top of this it will also be super clean so that it looks as good as it is. RMS and IMS seals are OK. The IMS is original and it will stay like that. It's the early two row which I belive really isn't an issue as long as oil is change frequently (10000km or once per year, which ever comes first). And, no engine tuning will be done, just have it run perfectly and reliably. Any added performance will come from removing weight. I'm an mechatronics engineer so I will also build some new stuff to replace some stone age technology on the car. This will be to improve function and/or reliability. The first thing on my mind is the crude(and not very reliable) radiator fan series-resistor. This have to be a last minut '****, we forgot to add low speed fan....just throw a resistor in there'. On my old 996 and also my new, they where broken. Also, when the fan runs at low speed it uses half that energy to just produce heat... One of the first light modifications was to remove the rear wiper: easy and looks much better without it disturbing the nice​​ 911 lines. If you are looking for a plug to the hole I have CADed on which can be 3D-printed and painted. The most light weight plug you will find. https://www.thingiverse.com/thing:3944012

Curious about your fan speed resistor solution.

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What are the miles on this car? Do you know if the engine is the factory original or reman? How did you confirm the bearing was a dual row?

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x2 If car sat for any length of time, I'd be concerned about the IMSB, they (dual row) are still failing to this day! "The Solution" would fix that for good if it passes a prequalification. Congrats and good luck!

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yea, and what I'm trying to address to the owner is that the 2000-01 996 cars could have single or dual row IMS bearings. I'm really curious how he knows the car is definitely a dual row.

Regarding which IMS: I've checked the engine serial number. Single row was introduced at serial number 66114164, correct me if i'm wrong. Mine is built before that. Was there ever a single row on the 3.4 liters? Car has just passed 170000km (roughly 100000 miles) and everything runs smoothly, original engine/gearbox. It also got zero time in 'ignition range 2'. I'm doing several precautions to avoid the bearing from going, mainly improving the cooling and changing oil frequently. The resistor will be replaced by a switching speed controller which uses the same off-low-high signal as the normal fan. I'm prototyping a unit which will look very much like the original but inside the tube there is electronics instead of the resistor. I think I will do some logic so that low speed will be more 50-70% depending of outside air temp. The same controller will probably work very well for the engine bay fan also. As I understand this fan almost never runs? Edit: Did some googling and maybe the serial number is not that good indication of which IMS bearing is inside.

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Yes, Porsche began implemented the single row bearing at the factory in 2000 on the Mk1 3.4L engines. We have to remember, these are all 20 year old car and it's well known these bearings wear out. Therefore, at clutch change, swap out the bearing regardless if it's a dual or single row.

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We'll be trying Koni Special Actives soon, supposed to be more comfortable and provide more control. Same springs so no change in ride height, if anything we need to go higher due to scraping. A voltage regulator controlled by a logic circuit could create a number of fan speeds. You know how to fabricate and have room to install a circuit card? What environment in controller area?

Instead of installing new radiators just clean them and then install the centre (3rd) radiator that the tiptronic and GT cars have. If the existing radiators are in good condition, replacing them will not improve cooling capacity but a centre radiator will.

I googled the Koni Special Actives. Looks like it's just for the C2? The current system have two power sources connected to the fan. One directly to run full speed and the other one have a series resistor for half speed. The unit I have in mind is the same size/shape as the current resistor and will use the same two power sources to determine half speed or full speed. The full speed will just be a jumper. The controller network will not know that it's there and the unit will need no digital information either. Completely stand-alone, drop-in replacement for the resistor. In my work I design and build a lot of prototypes for different electronics, avionics stuff.

New exhaust arrived today, nice and shiny. Inox and the welds look nice, 6,5kg each. Bought here: https://inoxlineperformance.com Also some new poly roll bar bushings. The first protoboard for the fan controller also arrived. Rather small but I don't expect more than about three watts of heat development from it. Even tho it's a in-theory simple circuit I don't expect to have a fully functioning unit until after 2-3 prototypes, sometime next year. Regarding the radiators, this guy seams to have good experience from just changing OEM for a pair of aftermarket full alu. Long thread but funny: https://www.pistonheads.com/gassing/...&t=1601182&i=0

How much where those cans?

690€ + shipping

Thanks for sharing the files of your wiper delete cover! Personally I would replace suspension arm bushes and top mounts before MAF and crank sensor when there are no error codes stored in the ECU. Should you decide to keep your double row bearing in place after checking it out (when replacing the clutch or flywheel) it is advised (on here) to remove the seal of the bearing. Good luck

What is a "mechatronics" engineer? Do you have dual degrees in mechanical and electrical engineering?

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might as well be, but I believe it's a degree in itself. Most of my friends who have that focus, are working in automation with machines that build vehicles.

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Never heard of it before. But, that doesn't mean much these days...lol

Long evening last night, replacing the front roll bar bushings. When I bought the car I looked at them and poked at them with screw driver. There was a soft surface and a lot of 'gunk' so I assumed they where disintegrating. When I got them out it turned out someone had tried to lubricate them with a very thick black grease, the bushings them self were still solid sans some wear on the inside. Anyway, new bushings in, looks cool. All brackets, screws and surrounding plastic cleaned. It's nice to work on a Porsche, everything comes apart so easy since it's been carefully put together with thread locker and correct torque. Two questions came to mind putting the wheel arc liner back. Aft of the wheel there is a fixation point at the bottom, but the hole on the backside is too far back for the plastic clip to attach. Is there supposed to be a special fastner there? Second, the foam seals are definitely dead. Anyone have a good tip what to use? I guess some kind of door sealing strip?

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haha! What part of SC are you from?

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I�m from Beaufort. I live outside Columbia these days......

Continued working on the car today. Started on the back getting the bumper off to access the silencers and spark plugs + coils. The disassembly was quite straight forward, undo a few bolts an off came the silencers. I wonder how much all the dirt and grime that's on the car weight? There is a pile of dust on the floor. Anyway, the 'old' silencers that came off is from Dansk and I'm replacing them because they are just straight annoying. They are really loud but not in a good way. After taking them off I made the 'scream test' thru them and compared to my new OEM style. The Dansk I think are just empty boxes, there is close to no silencing. When taping them with a finger the make the same sound like a empty can. The new once make more of a 'thud' noise and they really silence when screaming thru them. After getting them off I continued taking the coil packs out one after the other. And....no less than all have cracks in them. So, I need to get new once. After a quick look on the internet there seams to be a lot of different brands and manufacturer for these. Anyone have good experience with one or the other?

If those coils are still functioning, keep them as emergency spares.

Very interesting. I�m subscribing to this thread. 👍

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Ditto.

The coils are going in the bin, the car will not be a daily driver so I will never put these back on. After 19 years and 170kkm they have done their job. A set of 6 NGK coils is about 200€, not too bad. Yesterday evening I started CADing an oil filter socket but I ran out of printing filament so will have to wait a week or so to print. Edit: https://www.thingiverse.com/thing:3968493 The first prototype of the fan controller have been built and evaluated. Main problem is heat, it gets way too hot. The problem is that the MOSFET isn't turning on/off quick enough so I need to add a small IC that will drive it. I was hoping it could do without a driver....but no. I was also scratching my head if it might be better to put a central controller(for both fans) in the frunk instead of having it exposed to the elements where it is right now.

Parts are slowly arriving. This week the new coolers has arrived and I've ordered a new AOS (Air Oil Separator), spark plug tubes and oil cooler. The coolers was the cheapes I found on ebay. I haven't checked the fitting yet. The finish is OK, not beautiful but functional. You can't really see them when they are on the car so looks isn't that important. Well, I was checking the spark plugs a few days ago and noticed there was oil in the tubes. The business end of the plugs them self looked excellent. I know the previous owner change one tube because it was leaking so I figured the others are on their way out. A little preventive maintenance. I also note there was a lot of oil (looks fresh) just behind the tubes where the screw driver is pointing (see picture). Behind there is a T-connection (My car was built in august 2000 and have this type of valve...it doesnt show up on the mk1 996 drawings, which just have a bend, but only boxsters drawings) with a valve and a tube(which goes to the AOS) which I tracked down to be an overpressure valve. Why is there oil on the outside of that? After scratching my head I figured the AOS is not creating the vacuum it's supposed to do which causes an overpressure in the heads. This also exaggerate oil leak in the spark plug tubes since there is a positive pressure pushing it out. So, I'm replacing the AOS and cleaning out the tubes + intake. It requires a lot of work to get to so I'm doing the oil cooler at the same time, preventive maintenance. Then I will clean the engine block which is dirty from oil. This way I will easily see when oil/fluid is leaking in the future. While I'm waiting for parts I started with the interior. I started removing the forward center console and then the rest of the console which covers gear lever and hand brake. Some of my spendings was then refunded! I found no less then 11€ in coins underneath there, win. 100g of coins was removed, more performance. The fwd center console was 1.6kg. The main center console is 2kg. The gear lever is really sloppy as the bushings are worn out and the top is scratched really ugly (it has the silver in-lay same as hand brake). Not sure which direction to take on that. The original stereo (cdr-22 I think) went out, 1.5kg. And so did the amplifier in the frunk, 1kg. And the big speakers in the back, 0.4kg per side. I will only keep the speakers in the dash and they will be connected to a bluetooth amplifier(less then 100g weight), all music/sound will be over bluetooth, nothing visible in the cabin. The hole that the stereo leaves will be filled with a storage box, 3€ from eBay. I write about the weights, it's for my own reference, I'm not chasing the ultimate low weight, just less weight than stock. The philosophy of the car is 'Driver focused and beautiful, with a touch of comfort'. I like the airy feeling inside after removing the consoles. It also brings(some) the nice classic 911 straight lines back. Something I like about the early 911 is the outside is soft and sweeping while the inside is more straight lines, designed with a ruler. Maybe I will build my own center console (the one that covers the hand brake and gear lever) which is more straight, level and minimalistic.

Nice radiator! Check www.warehouse33auto.com for coils. When I bought mine they had the best price (plus 10% discount for rennlist).

Small update about AOS. I've spent most of the day researching the purpose and function of the AOS. Put shortly it reduces the over-pressure inside the engine and recirculates that air into the intake(recirculation is due to environment/air quality). It's not a stright pipe like on most cars but it passes the Air Oil Separator which pulls out all the 'gunk' from the air so that clean air is feed to the intake. This is good, becuse oil-mist lowers the octan which potentialy can cause problems like knocking. Well, so-far-so-good. But, what does the AOS do with all the 'gunk' it takes out from the engine air? It dumps it down into the sump, mixing with the engine oil. not. good. at. all. Here you can see what 3000mils of 'gunk' look like: You Tube Ok, I'm thinking a catch can would be much better. I prefer to drain some gunk from time to time rather than having it mixed with the engine oil. After a lot of googling I found someone who had done some research to how well they work: https://gallery.mailchimp.com/807089...Comparison.pdf Seams fairly easy to re-route some pipes and install a can? Anyone done it?

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It's been done and discussed at length here on RL. https://rennlist.com/forums/996-foru...ight=AOS+catch

I read thru the discussion. It's a mix of different solutions but most will keep the AOS in place and adding catch cans somewhere in the piping to/from it. I would like to get rid of it. I saw someone linked to the 'Stellan' solutions and commented on fuel trim issues. The obvious way of doing it is to take the vacuum from the standard position (after the MAF). This is how stellan did it. The problem is that you bypass the MAF so the engine has no clue how much fuel is going in. Porsche solved this by adding the diaphragm thing to limit the flow so that the short term fuel trim would adjust for it(I'm guessing a little here but makes sense). If you let it free flow it will just go outside what the standard lambda sond will be able to handle. AND, thats why it works by taking the vaccum from the airbox: then the MAF can correctly measure the air going to the engine. But, then you end up with a dirty air filter and fouling the MAF with oil....damn. So, I think a functional solution would be to use one, or maybe two for cleaning the air properly, good catch can (like the industrial filter ones I linked to above) and take the vacuum somewhere in the filter box. Maybe connect it after the filter but definitely before the MAF. The risk is then to foul the MAF/airfilter but you remove the bad oil and no more AOS issues. Think I prefer that.

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Hence the need for 4000 mi. oil change intervals...

After a small de-tour to the AOS thread I'm back here. My proposed system looks like the attached picture. What differs it from your normal catch can setup is the dual vacuum source: air box before filter and normal place behind the MAF. The car has a ECU map which expects some by pass air. By having a long and thin tube going there we can by pass some air to satisfy the ECU. I will be using I.D 3mm PVC tube. Tuning: I will look at the fuel trim on idle and shorten/lengthen the by pass tube to have close to zero fuel trim. The new catch can will dump it's gunk into a container which needs to be emptied from time to time. The normal AOS sump return hole will be plugged. The normal AOS coolant line I'm not sure what to do with, maybe add a small radiator on top of the engine? Edit: There will be a check valve at the air box connection to prevent the by-pass line from sucking air from there.

I think if you connect the the catch can to the air filter box you will end up with a massive crankcase vacuum leak and the engine will not run right. When you way you've dome research, does this mean you just Googled for hours or actually did some testing?

Before I do some testing I need something to test, right? I read up how it works and getting a good start for testing. Connecting it this way will create a little less vacuum than the standard system, mostly at idle. At full opening(of the throttle body) the difference will be minimal. At idle it will be the biggest difference since the vacuum is the biggest. 'Silk' in the AOS thread have his AOS plumed to the air box (and without the by-pass tube) and seams to work very well for him. Mine will be closer to OEM vacuum than his setup.

While your system looks like it will work in theory, how do you plan to balance the vacuum pressure? Are you just going to "trial and error" it with different diameter hoses until you get it right?

What you want is a slight vacuum in the (vacuum in this sense is relative the atmospheric pressure...that is, less than atmospheric but not complete vacuum) system so that you will avoid over pressure inside the engine. You need to avoid too much vacuum and higher than atmospheric pressure. It's not more complicated than that. While writing this I realised that my check valve that I 'Edited'-in in the post above will create too much vacuum if the by-pass tube is not correctly dimensioned. With the check valve in place the tube is the thing which mostly controls idle vacuum in the system. Otherwise it will be the vacuum in the air box. On second thought I might skip the check valve since it might make the system less robust. The small possible gain in vacuum might not be worth it. When connecting to the air box you will definitely have lower than atmospheric pressure, but not by much. I need also to add: The pressure in the system is not the same due to flow. When connecting to the air box the beginning of the system will have slight vacuum but you might have slight over-pressure in the engine. This is because of pressure drop/increase in the hoses, in the catch can etc. Larger diameter hoses, shorter hoses or less flow will make the pressure difference less. So, when using a weak vacuum like in the air box I will use large diameter, and short, hoses for the venting.

So the short answer to my question regarding "trial and error" is - yes. I think a way to test this (at least initially - assuming your AOS is still good) is to take a baseline at your oil fill with a manometer, and then build your catch-can device to that baseline. At least you'll have #'s to look at as opposed to guessing (if memory serves 5-7" is the manometer baseline for a properly functioning AOS?).

Why not just a stock AOS and be done with it?

It makes the following improvement iver the stock AOS: +No risk of hydrolock in case the AOS break +Cleaner air gets re-circulated (less oil in it) +No bad oil re-circulation in the engine +Easier to service On the negative -More labour, one more filter(every 40000km) to change and oil(5000km) to empty on regular times -Not original (but for me that is not important) And then we have the discussion of engine problems with the M96 engine. Having bad oil to lubricate the internals doesn’t help. And using it as an oil-burner(read sot) also doesn't help. For me this is the perfect solution as the oil in the engine is kept as clean as possible.

I do like numbers, I'm an engineer after all, but it's not necessary in this case. I know from the start I will have less vacuum than stock. That's beacuse I will not run the return to the intake, but to the air box. I will do as good as I can with this. 'Silk' in the AOS thread have been using the air box as vacuum source for over 45t miles and it's proven that it works( how good it works is another question). Will it matter? I think not very much at all. It's a give and take. I'll gain in much better oil quality and cleaner combustion which I think is better than a high vacuum inside the engine. As long as I don't have pressure it should be fine. And I will use the Porsche T-fittings to the block, which have PCV valves preventing over pressure. If I see oil on them I know vacuum is not enough. And yes, this is a plan, let's see how it turns out. I'm confident enough to test and develop it.

What better oil quality? I work in the engineering world to and numbers matter to me as well but I just don't think there is a real problem here that needs fixing. The stock AOS is a serviceable part and if people change them at a somewhat regular interval, all will be well. It is a self contained system that doesn't require any extra steps or procedures to keep it from working.

I guess I have to show some numbers to get some 'cred' here. So, this morning I went to the work shop and looked in my box-of-many-components. I fished out a differential pressure sensor which I wired up (with some high precision electronics) to an Arduino. Then, on to calibration. Accuracy is within roughly 1/10" h2o, but from now I will use SI units. A brand new AOS arrived in the mail (I ordered it before really understanding the issues with the normal AOS system). The test shows that it limits vacuum to 2.7kPa with some over/under shoot, see graph. I believe it's only idiots that don't change their mind. So, with this new information I will not build the system like I said before, it's going to be plumbed in a different way. Y is Pa, X is sampels. 10 SPS Test setup

Now the 3D printed oil filter socket is tested and working. The first one used a 1/2" driver which was not strong enough. Enjoy. https://www.thingiverse.com/thing:3968493

Good luck! I started down this rabbit hole when my AOS failed and decided to just replace it with a genuine part, keep my oil changed at 3000K or 6 months and manometer test once a year. When the time comes to replace my AOS like many other parts, I will do just that.

Can I ask why you decided to go original. Was it a lack of a good solution or just that you feel that the original is good enough? I remember that you adviced me to upgrade the IMSB to a 'IMS solution' in the beginning of the thread, and that's far from a genuine original part. I guess we are the same: selective of what can be, or not be, original. Continued with flushing out the oil in the afternoon, it's been in there for almost 20000km. As a proper 996 owner I cut the filter open and search with a magnifier for pieces from the IMSB. Lucky I just found microscopical metal parts (tried to take a picture, but with macro and tripod the pieces are just one-two pixels big). They are more like dust particles than pieces. A few plastic pieces of the same size was in there also. Thinking that the car have gone 10% of it's life since last oil change this is absolutely no worries. Good news, IMS stays in place untouched. It also means I can go ahead with another experiment of mine (O-yes, I have a lot going on). I bought an extra knock sensor which I will mount in the hole in the bottom of the crank case, close to the IMSB. Connecting it up to a spectrum analyser it will be possible to create a base-line FFT of a healthy engine. Not sure if it will show useful information or not, but I'm hoping it will be possible to detect a failing IMSB by the vibrations it makes when going bad. I worked for SKF(producing large roller bearings) when I was a student and heard about the technology. Can be read here: https://www.skf.com/binary/tcm:12-11...20Analysis.pdf Is it obvious that we got snow here the last days?

Wonder if a variation of a scavenger valve installed in the exhaust right after the muffler above the tailpipe junction would provide enough air flow and suction to evacuate the catch can? It would need a "purge valve" that opened only above 3000 most likely but in the old days it worked really well to vent a drag engine..

Nick, I don't track my car for one. I didn't want to clutter up the engine bay any more and felt that as long as the AOS can be monitored with a Manometer all will be fine (for me) as it's just another wear item like many other parts. As for the IMSS, that's the way to go, if I could I would, but I have the 997 type bearing.

I remember reading a post or two from Jack Raby that he tried using the knock sensor to detect a failing intermediate shaft bearing and the data was not reliable enough to make this work. I like your enthusiasm but most of what you are posting has already been tried in the past. I've used a self sourced intermediate shaft hybrid bearing and the end results were not good at all. The bearing was coming apart at the 12K kms mark. I have posted this on my engine repair thread but my pockets are not deep enough to keep trying this. Did it once, got lucky enough that the engine didn't grande and I am able to fix it.

Last week I received the spark plug tubes so that I could get started to put everything together. The only hick-up was that the heat shield over the coils didn't fit perfectly. The new coils(NGK) are a bit beefier and the fixation screw heads protrude from the unit and these touch the heat shield. If you look at the picture you'll get the idea how the heads protrude. I didn't do anything about it, just added some loctite and fastened reasonably. The new coils are also around 20g heavier. With everything together I started refilling the oil. After 8 L the stick indicated completely full, time to start and circulate the oil. The car have been sitting for over one months and had a complete oil drain (filter out and 24h drain period) so I was expecting a bit of rattle from it. On top of this it was rather cold, around 5 C only. Turned the key and it came to life with a lot of rattle and a loud tick from the cylinders. I knew that these engines make a lot of rattle but it was quite discerning, especially the ticking. The ticking was clearly not an injector or lifter, it was coming from the cylinder. I let the car run for 5min and then turned off. I'm treating the engine with tungsten disulphide so I have made an oil mix which is 1% wt ( 34g of WS2 powder to 3400g oil) mix which I will slowly put in there. I was able to put 1L of this in before the dip stick read full. I will do a new filter change shortly which will drain some oil so that I can fill more. With the engine full I let the car idle for around 5min (still loudly ticking) before slowly going to the petrol station. Since the car had been sitting I was afraid the cylinders was completely dry and thus I wanted some oil on them before setting off. It's only 2km to the petrol station and by the time I arrived the ticking was almost gone. After setting off from there It quickly disappeared. Due to the WS2 treatment I needed to directly drive the car(the stuff sinks, so after sitting still for a week it will separate from the oil and not do much) so I had planed a 1 hour drive. Dark, cold and rainy...it wasn't the perfect drive weather but the car pulled very strong and smooth. At arriving home I let the car idle at the drive way while I listened. When properly warmed up it runs silky smooth(!), the only ticking is from the injectors doing their job. The day after I started the car again, to circulate the oil before the WS2 sinks, and it's making this ticking noise again. Day after that I tried to pre-heat the engine before starting and this clearly made the ticking less. My idea is that the clearance for the rings are so tight that when the engine is cold they have too much pressure causing the tick. Could also be the AOS not properly evacuating the pressure from the crank case causing it. I guess there is a thread somewhere where the reason have been found? The new Mann+hummel AOS have arrived and I have been testing it. It's very similar to the original, so similar that it might be possible to use it sans modifications. I still built a pressure regulation adjustment for it if needed. I will let the short term fuel trim guide me. I bought the 200 size but I guess a smaller 150 or even 100 will work well also. At idle the blow-by should not be much more than around 60l/min so a size 100 would in theory work. The knock sensor have arrived also but it will need an amplifier and a band pass filter to bring out the relevant signal. Old vs New

Have you not watched JR's Bore Scoring videos?

Bill, it's not bore scoring. But, still a serious problem that I need to solve. I found an instructional video on youtube how to remedy this: You Tube

Now I have viewed JR bore scoring videos. The engine makes ticking noise just at start up from cold, but that's it, 2-3min. Spark plugs look perfect. No excess sot. Engine runs perfect and strong. No CEL. I took it for a drive yesterday (almost 2h of high RPM driving in the mountains, 3k-7k) and it ran perfect. After I check the spark plugs again, still perfect. No excess sot on either exhaust. I did a filter change and re-filled some oil and went for another 1h drive. All Perfect. In the evening I dissected the filter and checked the small amount of oil that drained during the filter change: nothing. When I bought the car it made no start up noise (I felt the engine before first start, it was cold). I also checked the exhaust pipes for sot. Since I bought it I have replaced/done the following to the engine: *Coils *Spark plug tubes *Checked all spark plugs, all in excellent (text book) condition. *Oil filter and oil *Air filter *new exhaust Logically something I did caused the ticking. I recorded (sound) the ticking to be able to measured the time for it to go away and to compare to others recordings. It slowly lessens and after about 2-3min of idle there is just a faint of ticking left. The sound is not like the bore scoring which I found online(which is a constant tick that doesn't go away), and it makes no sense that it will happen after an oil change either. I don't have a stethoscope to check exactly where it's coming from but the symptoms points to a tappet. I'm guessing the old oil was just thick enough to not drain too much while the new oil drains it and it have to slowly fill up when doing a cold start. The previous owner used 5w40 Motul 8100 x-cess oil (he gave me a half full bottle of left-overs from last change). I put in M1 0w40, I think this is my mistake. Since I have both 5w40 and 0w40 I did a small test. I drilled a 1mm hole in two plastic cups and fill them with the same amount of oil, one with 5w40 and one with 0w40. At 10 degrees C the 0w40 drips out 30% faster. I see now that Porsche them self( since 2018) recommend 5w50 for the 996. So, question is: Change to same as before or M1 5w50? I will also drop the oil pan and make sure there is no obstruction in the pick-up or return pipe, I read a thread here that it caused ticking problem. https://rennlist.com/forums/996-foru...-solution.html https://www.porsche.com/internationa...ghts/motoroil/ The AOS project is going along well, waiting for parts right now. The fan speed controller is a bit on hold since I can't decide how I should build the unit: One central controller or two small located at each fan. I need to take the fans off the car also to better see the options and foremost be able to bench test the system properly.

Maybe bad news. I went over the spark plugs with a torque wrench this morning since after finding a thread on here which indicated that ticking could come from loose plug. Before I just tighten by hand estimating the right torque (I never used a torque wrench on the spark plugs before). I found a few which was not tight enough. They all looked good but I took pictures of them to be able to more clearly compare them. Below is the picture. After starting there was still a tick but less than before. As usual it went away after around 2min of idle. Number 5 has slightly more sot on it, but still to my eyes not much at all. I have a bore scope camera on order so will have to wait a week or so before being able to look down the cylinder. Is it possible for sot to form due to badly tightened spark plugs? I'm guessing so and hope this is the case. I looked thru the receipt from the previous owner and the spark plugs have been in there for roughly 20 000km.

The plugs look ok to me. Have you put a mechanic stethoscope on the engine yet? I didn’t note that in your previous posts. You can put the point on each cylinder and check all around the thing to isolate the source. May save you a lot of time and keep you from throwing extra parts on it.

Those plugs look good to me. There will be some variation because the ECU doesn't know exactly how each cylinder is running so it makes adjustments across the bank as opposed to each individual one. That's just how it is designed. But looks like some of your spark plug booth O rings are leaking a bit.

Thanks for your replies, they are much appreciated. The spark plug tubes was recently (1 week ago) changed and some oil was dropped, that's why there is a bit of oil on the boot. Not been over it with a stethoscope, I don't have one, maybe a good investment. On my list of things to try next is Seafoam in the oil(to dissolve any sludge), 1h drive and then oil change(+ oil pan inspection). Changing to a thicker oil as was before in the engine. The valve train makes more noise than I would like right now(apart from the ticking), I hope some heavier oil can reduce that.

Nick - either buy a mechanic ear stethoscope (cheap) or a medical one (expensive). If you don’t buy the cheap one, you’ll need to buy the expensive one to check your heart each time you start the car.

One thing concerns me. You changed your oil in 5* weather to a thicker oil after a 24hr drain. Oil filter filled? Then started it and let it idle? Did you start and stop (3-5 times)...to build up oil pressure before firing it?

I changed from Motul 8100 5w40 to M1 0W40 (I was a little unfocused when choosing oil. Where I live it seldom goes below 0* centigrade and summer is 35* c), after a 24h drain. After the change I just started the car directly and idle for around 2min. Stopped and topped up oil. After this I went for a 1h drive. I've now read it could be good to pull fuse C4 (fuel pump) and circulate oil before starting, which I have been doing since. I run the starter until I have 2.5 bar pressure and then put in the fuse and start. on a side note: Fuel pressure seams to drop to zero after just 24h, is this normal?

No need to over think this. The bearings will still have enough oil on them to be ok even if the case was drained for 24rhs. It's not like they are bone dry when and engine is first fired up after a rebuild.

While waiting for the camera to arrive I have been working on the interior. Here is a 3D printed cover when doing the centre console delete: https://www.thingiverse.com/thing:4018981 Enjoy.

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I would reconsider this method. Have you tried bore scoping cylinder 5 and 6?

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Cool. Keep up the good work.

Camera finally arrived today, below are the bore scoping results(lots of pictures). Shortly: No evidence of excessive scoring but points of concern. So, can I see any cause for the ticking? Yes, check the bottom of piston 5 and 6, they are shiny. Why? I guess the injectors are leaking (as mentioned before, my fuel pressure goes to zero within 24h) and it ends up at the bottom of the cylinders/piston, effectively cleaning off the sot there. It will also clean off the oil from the cylinder causing different coefficient of friction from top and bottom of the cylinder. I guess this will cause the piston rings to move and maybe also the piston to tilt back and forth at a cold start, causing the ticking sound. As soon as the cylinder is oiled properly the sound goes away: the piston is moving as normal. There is one thing of concern that I need the forums help for. Check the top of piston 5. There is a spot there which is clean from sot. Are the clearance so tight that just a few mm of tilt will cause the piston to hit the head? What to do: It could be possible to take the injectors out and clean them one by one, identify which once are bad or not. I would do that if it was my daily. On the Porsche, I will just buy all new. At around 85$ each it's quite expensive but so, it is an expensive car and a hobby. First: Cylinder 1 bottom/top as reference cylinder 6: bottom/top, bottom, top cylinder 5: bottom/top, bottom, top. The small black streak on the bottom here is most likely only a smear of sot. It appeared while I was turning the engine to position the piston at the bottom. Edit: What a proper scoring looks like(32min20sec)). Many thanks JR!. You Tube

Injectors aren't that expensive... https://www.warehouse33auto.com/BOSC...996-606-122-00

Looks like something has been bounding around in the cylinder. Are you sure there isn't a washer or something foreign in there. The top of the piston looks really beat up.

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Also, discount code is RENNLIS T for an additional 10% off.

Imo000: The camera is rather **** ( as expected at 26 USD delivered) so the picture is a bit so-so. But, when looking at the video and moving around it does give a good picture of what your are looking at. I spent a lot of time looking at the pistons and they have no markings from any collision what I could find. The thing on the nr5 piston top side is just the sot which is gone, the surface seams untouched. Thanks for the injector buying tip! I've fired off an email to check the shipping.

Then I suggest you get a better camera or else you'll be chasing optical anomalies.

So, I'm in the middle of replacing the injectors and noticed something odd. When taking off the intake manifold I could see the oil sludge build up on the mating part on the engine(the aluminium part which also the injectors are attached to). cylinder 1-5 showed equal sludge build up while 6 was almost clean, big difference! There could be two things happening: 1. More/Less air getting to the cylinder and hence less oil sludge build-up. 2. Part of the intake works like the original AOS and separates out the oil from the air before it reaches 6. First scenario it would get more/less air than 4&5 and would be running rich/lean. This was my first thought when seeing this. Second scenario, the air which reaches 6 is actually cleaner with less oil in it. How would this affect the running? Well, 4&5 have an oil mix in the air which means they need less fuel. The closed loop fuel trim will adjust so that the sum of all three (4,5,6) will produce a good combustion. This means that 4&5 will run slightly rich while 6 runs rather lean. Since the intake to 6 is cleaner it also have less resistance leading to even more air going in and leaner running. With what others have reported, that bank 2 runs hot ,I would guess scenario two as the most likely. Remember where you heard this first. I will clean up everything and then hopefully my AOS solution will prevent this in the future. On a side note: it would be nice to see someone build a proper CFD optimised aftermarket intake manifold.

I think your AOS has or is failing. Did the parks plugs verify your theory?

When my AOS failed, the oil went to #4

First a picture Everything is back togheter and working. Since last post I have: All new injectors Replaced AOS including the two purge hoses (all original) New radiators, all aluminium New coolant New thermostat, 71 degrees. New fan resistors (put normal resistors for now) New wheel bolts, the old was a missmatch of different types which caused vibrations. All adjusted to within +- 0.2g per wheel. Removed rear 15mm wheel spacers which previous owner had put on. Replaced all idler pulleys and belt Et voila, the ticking at cold start is gone ! It previously ticked at cold start (loud and clear) for around 1-2min while fading away. The sound from the engine is now a pleasant noise of mechanics doing their job. The idler pulleys was also rather worn so i replaced them, reducing the engine noise even more. I went for the newer 997 plastic once and they are noticeably lighter also. Well worth the money and time spent. It took a long time since I replaced the AOS twice. First with my own system which turned out to be a larger project than intended, vacuum regulation was not directly plug-n-play. After a week of trying to get something close to standard I had enough and put back to original. It will be for next winter.

Get the ultimate AOS Solution from Porschetech3!

Always nice seeing these threads have a good outcome.

Just a small update to keep track of what I have done to the car. On the test drive I did a little over one month ago I had, in my mind, quite high engine temp. The needle was fluctuating way over the thermostat temp (on pretty much every other car the temp needle is glued at the thermostat temp) and it was only 20 degrees outside. Reading on Rennlist plenty of people reported the same and wrote it off as normal. I started a separat thread about it which can be found here: https://rennlist.com/forums/996-foru...-radiator.html In summary I was able to improve cooling significantly with an easy hack. During the winter I've had the wheels off more times than I can remember so I have made a 3D printed 'revolver' to hold them (clean) while they are not bolted to the car. Can be downloaded here: https://www.thingiverse.com/thing:4260756

A 20 year old car has a long list of things that needs to be sorted. Since I wrote here the last time I have: -Replaced engine mounts with a new pair of original -Replaced the exhaust collars. The PO had some how mangled them so they were not tight -Installed x51 oil pan and put new oil in -Polished and waxed the car (wow, it's full of stone chips and scratches) -Cleaned the wheels -Put everything back into the car so that it’s 100% original -Pressure tested the cooling system While replacing the engine mounts I noticed that one coolant hose is on it’s last legs(cracks in a T-section) and needs to be replaced ASAP. I will go thru all the rest to see if any more needs replacing. I will revert back to the standard 83c thermostat also. The low temp thermostat just makes the car worse and does nothing to protect the engine, it’s useless. On flat ground, not too hot and moderat speed the coolant only goes to around 80-82c. That’s too cold. I’ve analysed the system and found that a lot of the common arguments for the LTT is based on misconceptions how the cooling system works. Don’t ever let the engine run slower than 2500rpm when driving hard and all problems related to overheat will be mute. Idle in conjunction with hard driving is a killer, you need to cool the car down before idling. It boils (pun intended) down to the fact that the water pump needs to work between 700-7300RPM. There have to be done some compromise with such a large span and as such the flow at idle is just minimal. You know this if you ever filled the coolant, it just doesn't pump very well at idle, you need to get it up to 2500-3000 rpm. I might consider installing a 3rd radiator next winter because my driving is quite often uphill/downhill with rather slow speeds, but high load on the engine. This causes coolant to run hot (boiling or more) too often. Old engine mounts. Saging, cracking and tilting.

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yea ok And the thermostat is at the hottest or coolest part of the coolant circuit? don't make ridiculous declarative statements

SO just put htis in perspective.. Both Hartech and LN engineering recommend the cooler thermostat.. so your putting you new to you knowledge about the 996 engine against the two top authorities on the 996 in the world.. FWIW,, GM LS engines do the same thing,, they have the thermostat on the inlet feed not the outlet feed, look at the flow and where the temp sensor is at. In my experience caring for a lot of track cars.. 80c/176F if freeking perfect for a aluminum engine..

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You forgot that Porsche choose 83c...but I guess they don't know what they are doing? LN, Hartech, FSI etc cater for very specific needs...not necessary good for the general user. Do your track cars run at 80c when on track racing? That is the problem with the 996, you can put a 71c thermostat but when pushing it it will keep heating up even when the thermostat is fully open(EDIT: see a few post below, thermostat was jammed), the cooling system just isn't strong enough to make use of the lower one. It needs a bigger dT for the radiators to shed the heat. The temperature fluctuates between 80c when going slowly and then still running +100c(or more) when pushing, the thermostat makes no difference(in lowering high temps) but running the engine unnecessary cold when you don't need it. I can't find the link right now but I read that the ECU is running in 'warm up' mode until something like 87c. The cooling/engine just isn't built to run with a 71c thermostat. I would like to run the engine in a tight, controlled, temperature span. Best/easiest way of achieving that is to run standard thermostat and then add more radiator area. The thermostat sits just in the return path from the outlet of the engine(one of the hottest places before it starts to open), maybe the coolant cools down a few c from the reading you have of the water temps. The temp sensor sits maybe 30cm (1 foot) upstream of the coolant flow from the thermostat. Think about it, how does the water circulate thru the engine before the thermostat opens? Look where the thermostat sits, there is three(+ the return from radiators) inlets to that chamber, where do they go? Look how the chamber is designed, the more the thermostat opens the more the flow from the internal recirculation slows down...it's a nice design. EDIT: It's nice because it mixes incoming radiator water carefully with internal water to avoid running too cold water into a hot engine causing thermal stresses. If you put the thermostat on the outlet you will have a more aggressive flow increase of cold water into the engine. If something is unclear, please just ask, I'll try to explain as good as I can.

Try to get your hands on a 3rd radiator kit from a Boxter S. This will increase the capacity of the cooling area at the front of the car.

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We might just have to agree to disagree on the optimum path.. Lots of ways to manage heat.. My background is in managing vary high capacity Data Centers and cooling is a war.. I tangle with it this way.. Cars I've modified have maintained a 170 to 180 Degree temp consistently through a 12 hour enduro.. Air temps over 100.. Fwiw. I always work air flow as high as I can first, partially by getting control of the fan ,, most ecus are set for a compromise that often is at least 30 degrees too high, and they turn off too low. (Too low in terms of keeping the engine at a steady temp. ) then work the flow of the air through the radiator, and around the engine,,, then I optimize the coolant flow, Usually some clean up and machining in the system. For track I run commercial wetting agents in the system to prevent / control any air bubbles. There's more to it in the big picture, but that's the gist.. If ya cant finish a race, you cant win them.

Yes, it's perfectly fine to disagree. Thanks for your reply. I think you have answered what I have discovered: Just changing the thermostat is not enough, there is a lot more to it. This is what I've done so far: https://rennlist.com/forums/996-foru...-radiator.html My goal is not an all out track car but a road car which will last a long time driving it mainly on road. Running as low as 80c I believe is not optimal for my goal. I've read that some people have been able to re-program the on-off temp for high-low speed fans. That would be nice but I have so far not found how to really do it. I would like to keep the car as close as possible to stock so it's a bit of a balance what I'm prepared to do. The 3rd radiator was standard on the tiptronic and x51 so it doesn't look out of place.

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This is true but my 2000 C4 Cab seems to have required a lot less attention than your car (knock on wood). Still, I've already paid $3k (mostly labor) for necessary "fixes" plus $1.8k (parts & labor) for a complete brake job due to be completed this week. ​​​Add $400 for a new set of wheels & tires (my $1.2k stim ck paid for the rest) and $100 for a manometer and adapter to test my AOC pressure (which was good) and I'll be all done for now. Whatever else I'm thinking about doing is purely optional. Not bad for a 20 yr old car IMO. LOL!

Uh-oh, found something today while replacing the thermostat and some coolant hoses: What you are looking at here is a Wahler 71c thermostat which is not working properly. It's been in the car for around 1000km. When the thermostat opens the plate at the top slowly moves toward the internal circulation to cut it off and the spring below the plate allows the thermostat to open more even after the plate is seated. What have happened here is that the plate have jammed on it's shaft and restricted the thermostat to only about 70% opening. That explains quite well why I was still seeing so high temps when pushing and also explains why it's good to buy original spare parts. I've just made short trip with my new OEM thermostat and so far so good, max 98c and minimum 91c with 31c ambient. The thermostat design was also a bit different. The OEM have 1mm more restrictive flow for the internal recirculation than the Wahler when closed. EDIT: distance from t-stat flange to recirculation tube is 37mm. The gasket is 0.7mm thick uncompressed. OEM Wahler 71c I also took the time to examine the inside of the water pump. It is easily done with a small camera when the thermostat is off. All good.

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4-6" in a healthy stock engine with a stock AOS.

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Is failure usually over a period of time, as many report some increasing symptoms before outright disaster, or does it tend to be sudden?

Short follow up on the thermostat. With the OEM, max temp I’ve been able to provoke is 108c going on my “hill climb” road. 108c was reached beeing stuck behind another car at 40-50km/h, as soon as I get the speed up over 70km/h temps drops below boiling even when pushing(33c ambient). On the high way in equal hot weather the car sits at 87c and thru rush hour traffic(10-20km/h and some stop-go) with full A/C, coolant temp reach up to 98-99c. My theory(just a theory ) for the Wahler is that the wax continues to expand even after the thermostat is fully open which causes the brass tube to expand and jam the pressure plate. I’m calling it good for now, on to the next challenge. So, I’ve noticed two things while driving. The steering wheel vibrates over 50km/h and the car pulls clearly to the right. I’ve started putting together a wheel balancing tool but decided to have a look if I could see something obvious first. So, I found that a super mechanic have been working on the car: Screw clamps on CV boot That is probably some of the vibration but not all. Come on, he could at least have put them 180deg apart? I have a crimp tool and some proper Oetiker CV clamps on order. Right side disc, even tho being almost new, had a chip in it. I will probably remove some material (drill hole?) 180 degrees shifted from the chip. Chip in brake disc Continuing with the investigation I found that the right side top mount is positioned for max negative camber while the left side is positioned for max positive camber. That is: both are shifted max left when looking in the driving direction. That should give some camber pull to the left, but car pulls to the right, hummm. Continuing I found that the right front spring is probably not original(the shock looks original tho), it lacks the color markings.

Nick, your a smart guy, so i assume you’ve done a full alignment. If so, and the top mounts are at opposite extremes, something is seriously bent.

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Last alignment was 25000km ago (two years) so I rigged some lines yesterdays to check toe at least and it's spot on. You read my mind, bent. Been looking hard but there is no sign of it. This afternoon I have been on it. Right side damper wasn't seated properly in the wheel carrier, 1.5mm gap due to gravel/sand blocking. I was a little too fast to say that camber was maxed out, it wasn't. Right side is now maxed(4mm extra) and left side is very close to max, both sides are equal now. When adjusting the camber the toe is affected so have to do that and then off for a drive.

Did you measure the camber? Don’t necessarily rely on the placement of the slots. If you don’t have a camber gauge, you can do a quick and dirty measure with a bit of flat bar or stick and the measurement app on an iPhone or equivalent Android device.

Hey, at least they used motorcycle screw style clamps and not the regular ones that chew up the CV boot!

The alignment is sorted, it now drives perfectly straight. I found no damage or other things indicating a crash so I guess my shell is produced on a Monday. Since I got the car I have been doing the trick of pulling the fuel pump fuse(and prime the oil pressure) to reduce the cold start chain rattle. This past week I ordered new chain tensioners and had them installed. First surprise was that my car(built 08/2000) had the newer type of IMS-Crank tensioner (indicating tooth-chain and newer IMS bearing?), so I had to place a new order for the correct tensioner. Good thing, because my back had enough for a couple of days after doing the bank 2. All the tensioners was completely shot. Bank 1 tensioner came out half depressed. After tapping it 4-5 times on the floor it snapped loose and extended fully. Today I got the last tensioner installed and I also replaced the worm clamps with Oetiker crimp clamps on the forward CV boots. That went easier than expected. Before starting I need to refill the power steering fluid, but all shops a closed today because of national day. Tomorrow there will be PS refill, engine start and a nice drive. Old tensioners Oetiker crimp clamps and tool. Worm screw weight. That means 18g of un-balance weight per CV boot.