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YOUR RESEARCHRebuilding 996's engine
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Replace depending
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I have an aftermarket warranty that may try to have the engine rebuilt as opposed to replaced depending on cost and degree of damage to the engine.
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Only replaced the head, never got to the bottom end.
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Suggestion · Original poster
If my oil is clean, I will start this process soon.
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normaly I wouldsay pull the cam coversand inspect the chain.
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Suggestion
I would drop the oil filter and inspect for metal.
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Just curious to see if anyone out there have rebuilt their own 996's engine? It seem that every engine related problem everyone suggust buying a new engine.
I have rebuilt a couple of the top end of bmw's engine in the past as well as replaced the head gasket and I can't see how porsche's engine would be impossible to rebuild. To replace an engine with just a blown head gasket is rediculous.
I'd like to know that if an engine fails, would it be a better idea to have it rebuilt? (Assuming I am going to dismantle the engine in my garage, take it to the machine shop, replace all necessary parts such as rod bearings, head gasket, pistons rings, etc, then reassemble it myself) In my mind, this will only cost a few grand at most plus my many hours of labor. Plus I think its fun and a good experience where I can learn about the flat 6.
Also, upon quick research I have found this...
http://catalog.worldpac.com/zygmunt/...ine+Gasket+Set
And they have many other engine related products here:
http://catalog.worldpac.com/zygmunt/...Children=false
I believe the parts are available. Examples:
http://www.pelicanparts.com/PartsLoo...-10-Frame3.htm
http://www.pelicanparts.com/PartsLoo...-00-Frame3.htm
http://www.pelicanparts.com/PartsLoo...-05-Frame3.htm
If you are able to rebuild an engine by yourself, you are a lucky man.
The main handicap to pay for a rebuild engine in a mechanic dealer is the labour cost. A good friend of mine is an independent Porsche specialist and he told that It's cheaper to buy a new remanufactured engine than rebuilding it in his garage.
Too many hours of labour...
If you save this money in labour cost, you could do it cheaper
Does your friend have any info on where is the best places to get parts?
I am not too worried about labour hours as I will be taking my time to have it completed. Also, I think this may be a good learning experience.
FWIW - I was told that the Boxster 2.5 & 2.7L engines have been released from Porsche's hold and will be no longer available as replacement motors in August this year. I am sure the 3.4L for the 996's are not far behind. Look for more and more aftermarket groups making upgraded items in the near future.
C.
My engine is making a knocking sound like a loose coin in the dryer. The sound is very inconsistant and appears to be coming from near the IMS area. The car still runs 100% normal but I havent driven it much.
Worst case is that I will rebuild the engine. I will find out soon enough but I sure hope this is not the case.
Also, I was told that Porsche does not sell parts to rebuild engines. Is this true or are the shops bsing to me?
not sure about the na engines, but according to some well tuners you will need to spent at least $4k to $5k just in special tools to re-built the tt engines.. that's a big investment right there...
Sounds like the IMS failed and the nut is rattling around in the bell housing, if thats where the noise is really coming from. If you want to have a rebuildable engine don't run the engine any more than is absolutely necessary. I would drop the oil filter and inspect for metal. If the engine is rebuildable, ie no damage to the case halfs/cylinder walls, the only real obstacle to doing it yourself is not having the special tools. You need a special set up to install the piston wrist pin cir-clips for the bank 1 pistons, IRC(Its either bank 1 or bank 2, I dont remember which side it is for sure). You would have to get really inventive in order to install the wrist pins without the factory tools. There are a lot of other tools which the book calls for but most things can be done without them but if you blow putting in a cir-clip itll fall into the case and you'll have to split the case again and fish it out then start all over.
Thanks for the response and that is very informative.
I have a few questions. If the IMS fail, would the engine still be running as good as it is now? When I rev up the engine slightly to about 1100rpm, the rattling goes away. Any ideas?
I'm not speaking from experience on these motors, but should the intermediate shaft fail completely I would think your whole valvetrain would stop moving
The term "IMS failure" is a really a very broad term. The term "failure" is kind of an exaggeration. The intermediate shaft runs parallel with crankshaft right? At the front (crank pulley side) it drives the oil pump and has the sprocket for the timing chain for bank 2. At the rear (bell housing end) theres the sprocket for the timing chain of bank 1 and a bearing for support. The bearing center section has a M8 stud that protrudes through the support and is held with nut. You may have seen pictures of M96 engines with the transmission/flywheel removed and you'll see the nut below the crankshaft/rear main seal. Well, when you hear the phrase intermediate shaft failure it would lead you to think the intermediate shaft snaps in half. What actually happens is the M8 stud shears off and the nut falls off backwards into the bell housing. This will sometimes cause an oil leak and sometimes a nasty noise as the nut bounces around inside the bell housing but in some cases the engine can run as if nothing at all is wrong because the main portion of the IMS is still spinning and driving both timing chains. Eventually what happens is the IMS runs without support and able to walk around and results in all kinds of metal dropping into the oil pan which eventually gets sucked up by the oil pump and you can imagine the rest. But to answer you're question, an engine can for a period of time with an "IMS failure" and you wouldn't even notice.
I would say you need to inspect the oil filter for metal however before we start to make any conclusions on what may be broken.
That's the first time I've seen the IMS "failure" described technically, thank you!
So is it something external like torsion to the motor or internal like say vibration of the shaft itself over time which causes the m8 to lose its head?
Is the design (one sprocket on either end) the same for 3.4L & 3.6L? For some reason I remember seeing a sprocket with two sets of teeth on the same end (which I assumed drove the two banks from the same end) in pictures of the IMS I had seen when initially researching my purchase.
I looked through the work manual and the valvetrain looks pretty complicated. There is a lot of specialty tooling you can't get at Autozone..........
So, to rebuild an M96 in your garage ain't gonna happen unless you have some good buddies workin' for Porsche.
That was what a lot of peole said way back in the days about M3 engine but I manage to get by. I have also looked over the workshop manual and it seems pretty straight forward.
I will double check to see if there are any metal in my oil soon. If my oil is clean, I will start this process soon.
PTEC - Thanks for the explanation of the IMS. What you described is exactly what I am experiencing. The sound is from the rear of the engine near the flywheel and it does sound like a nut bouncing around inside. We had the transmission dropped and removed the flywheel and noticed that the bolt where the IMS is have been worked on in the past (bolt is kind of rounded).
Check out this website for some good pictures of IMS. In the third picture it shows two different IMS. The one on the left is the latest version which has upgraded the M8 stud to a M12 and also uses a larger nut, among other differences.
E36 - I had a blown head gasket and at 275k miles, decided to just rebuild the whole thing.
My Buddies E46 - He drove it while overheated and warped and cracked the head. Only replaced the head, never got to the bottom end.
I got a little intimidated by the little actuators that hold the 2 cams together and index them. I guess if you held the cams together and pulled them as a unit, might be ok?
Also, you have to have those bolt thingies that preload the timing chains. Don't know how you could get around that without having one to use as a reference.
Please PM me and I can get you the details. Some tools, we had to get creative and fabricate it.
Back on topic..PTEC, do you have the website to the pictures of the IMS upgrade?
Whoops, sorry about that, forgot to include the link. Third picture shows both shafts.
http://www.autofarm.co.uk/engines/wa...led/shaft_tech
Anyways if you have removed the transmission and flywheel and the nut is still there, then you don't have the classic IMS failure. Again I would be very curious to see what you find in your oil filter.
The transmission and flywheel is out and the nut is still there. However, the nut appears to have been tampared with in the past as it is sort of rounded off. I also checked the oil and it seems normal without any metal in it. It sounds like a loose bolt bouncing around coming from around the IMS area in the back of the engine. The sound is fairly loud and I can get sound sound clip if it can help any. Any ideas?
well i would say the most likey is a broken link on the timing chain
normaly I wouldsay pull the cam coversand inspect the chain. BUt if you have a 3.4 you cannot
take off the valve covers with out a cam hold down tool or you will break the cams. you may be able to pull the oil scavange pump and see the chain though
auto zone probaly not, If you were to remove the chain tensioners you could likley get away with pulling the cover and not breaking anything, but you will need the tools to put it back together
I have a related question. I just learned that the IMS "failed" on my 2000 C4 with about 50k miles. The IMS nut was indeed sheared off in the bellhousing. The car was still driving, however. At the shop, the tech showed me that there were metal flecks in the oil filter. I have an aftermarket warranty that may try to have the engine rebuilt as opposed to replaced depending on cost and degree of damage to the engine. The question I have is what the metal flecks in the oil filter likely mean about the nature and extent of damage to the engine and whether it is even possible to rebuild a 996 engine in this situation as opposed to replacing it.
Thanks for any info you may have.
We have a 2000 996 with #7 main bearing damaged but crank surface good. #6 rod bearing is gone with some heat cracks on the journal. Has anyone welded up the crank and reground and hardened them with success. Customer is sick of pouring money in it. Not to interested in buying new crank and haven't found a used one yet.
You can rebuild an M96 engine.
I worked along side a mechanic and did it on my Boxster 4 years ago.
I have since done a couple more.
My mechanic made all his own special tools from Home Depot stock.
The hardest part is the piston wrist clips. The second set is a blind assembly.
The only tool we purchased was the camshaft holding tool -- but this could be made too
if one really wanted to.
mike
Jake Raby's company, Flat Six Innovations, holds M96 engine rebuilding classes from time to time. I believe they're about $1000-$1200, plus your travel costs. Given his reputation for building rock-solid M96s, that would be money well-spent if I were to tackle an M96 rebuild for the first time. I considered doing just that (I, too, am a decades-long gearhead and do all my own work). But after adding up parts and cost for machine work, etc., I decided to have Flat Six do the rebuild.
Of course that cost substantially more, and everyone's budget vs. time is different. There are some things they're able to do (port/polish using a flow bench, dynamic balance of rotating assembly, and so on) that I can't. Back to your question, though, I would check out their class and schedule. On a Porsche engine, not hard to mess up $1000 worth trying to totally DIY...
The questions were, "Has anyone else rebuilt their own engine?" and "Would I be better off doing it myself than having it done (presumably by an expert)?"
The simple answers, I suppose, are, "Yes" and "No." The M96 ain't your daddy's big block.
This is what I was referring to since this is the only recent question that was bumped since 2008 that immediately needed an answer.
I think it's safe to say the people from 2008 already got the answers they were originally seeking.
My 3.4 crank was welded up and regrinded to a 3.6 stroke crank and then heat treated to harden the crank but we decided to use a factory 3.6 crank and crank carrier and have it balanced and cross drilled for extra oiling.
I am sure that you could have a 3.4 crank repaired the same way with success. We just did not want to use the weld/grind since we are trying to push this motor to 600+ hp. My shop actualy used it on another build that was staying naturally aspirated unlike my turbo build.
