996 ticking lifter/valve noise fixed!! my findings and solution

Hello all, I wanted to post this thread as i have been trying to fix my car for over a year. I have scoured rennlist and other forums but none that i have found have had the same problem/solution as me so hopefully this will help someone down the line. I Purchased my 1999 C2 6sp with 98k miles in June of 2016. I bought it from a private dealer as an "as is" deal for $13,700. the 911 was in overall very good cosmetic condition. The engine/ vehicle drove perfectly but had a light tick noise when it was warm. the tick would go away after it idled for a minute or so. the idle was also uneven and it was throwing a camshaft deviation code (p1342 i think). I was also getting a p0306 cylinder 6 misfire code as well intermittently during idle or low rpms. I have a lift in my garage and was confident i could fix the issues. Getting it home to the shop i could see that the AOS was leaking a large amount of oil. So i put that on the first order of business. I decided to do it with engine in car. I also wanted to inspect/change IMS (of course dealer didn't know history) so I decided to remove the tranny to replace AOS. The RMS looked new and the IMS felt like a brand new bearing when spinning it with my hand so I decided to not worry about it for now. replaced clutch as the friction disk was spent and new slave cylinder. Car back together no change. still rough idle/tick and same code camshaft variance code. So next I decided to take engine out and do lifters and check camshaft pads/tensioners/timing. Engine out, I start with Bank 2 (cyl 4-6) as that is the code that is popping up. inside the cam cover I find that the wear pads are so worn/thin that the corners/edges are missing. (I have pictures but they are on an old phone). Replaced the wear pads/tensioner adjuster/ lifters, re-time, and reassemble. Initially i was just going to mess with cyl 4-6 but after seeing how bad the wear pads were i decided to also replace bank one. Take bank one (cyl 1-3) apart and find that the camshaft wear pads are brand new???? this puzzled me a bit but as i already have it apart, I replace just the lifters here and reassemble. I also found a very small vacuum leak in one of the lines under the intake manifold. so I decided to replace all lines there while i had engine out. put engine back in car runs great. idles good, no longer uneven. but the tick is still there when it gets hot. noise is coming from valve lifter area on cyl 4-6 side. i also notice the tick turns to a clack the longer i drive it. if i sit and let car idle it would be ticking away but if i let it idle for a minute or so, the ticking will get lighter and lighter till it eventually goes away. I talked to a tech at Leith Porsche in Cary NC about my problem and he asked me to bring it in so he could take a look at it. So I do and he does a full diagnoses with their software/tool checking all sensors actuators etc. he also uses stethoscope to pinpoint the tick. Overall he says engine is healthy and everything looks good working as normal. He even says the oil pressure is good. he says noise is coming from cyl 5 exhaust valve area. he recommends checking the oil passages to that cyl, valve springs and thinks possibly might have gotten a bad lifter from the batch. So i take it apart again. and find one of the cyl 5 exhaust lifters is completely collapsed and empty of oil (it literally weighs half as much as all the other lifters). So i think "Glorious! I found the problem!!" but while i have it apart i take out the lifter carrier and inspect everything. the carrier looks fine and all oil passages are clear. Also i note that other than being squishy there seems to be no adverse wear on the lifter, camshaft lobes or the valve on cyl 5 or any other cyl. I install a new lifter and reassemble. problem still exists. !!!! At this point Im starting to read about rebuilds and scouring forums about what this could be. i couldnt find any other solutions/suggestions of which I haven't tried. I tried using different wight oils (0w-40, 5w-40, 10w-40, 15w-50) tried adding slightly more/slightly less oil. nothing made a difference. the only thing the oil weight changed was that it seemed to take longer for the ticking to appear with the heavy oil but once the ticking sound started it was worse, it also wouldnt go away when idling like it would with 0-40 or 5-40. But driving it with the heavier weight oil i also noticed that immediately following spirited driving the drivers side (cyl 1-3) would sound very clattery like an engine running with too little oil. This scared me and led me to look into oil starvation. another thing i noted was that when cruising, if i stomped the gas the oil pressure would drop sharply for a second before shooting back up. so I decided to remove oil pan to see what I saw and apparently I should've started there. the Oil pickup tube was very plugged with gasket and wear pad debris. there was also lots of debris in the depression of the pan which i'm guessing that while the engine was running was getting sucked up into the pickup screen and blocking the flow even more. i decided to inspect the oil defoamers AOS as while i was in there. I was surprised to find that the tube going to AOS on cyl 4-6 was completely blocked full of plastic wear pad debris. about 3 inches worth of blockage. cleaned all this out and reassembled. the opposite AOS was clean and clear. I resealed the oil pan and let cure. refilled with oil and the car runs now like it has a new engine!! it feels completely different. what i think happened was that (before i owned the car) cyl 1-3 camshaft wear pad wore so thin that one of them broke off and got chewed up and strewn about the engine. there was some metal chunks in the bottom of the pan as well. I am hoping that this was from before when the wear pad broke and the chain had to of hit the tensioner/adjuster. i am hoping there is no longterm damage or effects from the metal. the interior of the engine at least what i have seen looks like it could be a new engine. i notice no bearing wear on any of the camshaft surfaces/bearings or lobes. there is no sludge build up anywhere. It has been 500 miles since it has been all put together and Im still all smiles hopefully it stays that way. I attached some pictures. The first picture is my yellow catch pan. The debris in here is the rubber sealant and chunks that i removed from the oil pickup screen. In the second picture of plastic debris, this was removed from the AOS/defoaming tube. The Third picture with the debris and the metal chunks/flakes was removed from the oil pan and pickup tube depression. there is one picture of cyl 4-6 with cam cover removed was just to show how clean the internals are. and lastly just a pic of my car I took this morning after another smiling drive! IMG_20170818_085120266.jpg IMG_20170818_085058532.jpg IMG_20170818_085053903_TOP.jpg IMG_20170813_071709423.jpg IMG_20170826_100429912.jpg

You are very persistent. Thanks for sharing your story and results.

"the Oil pickup tube was very plugged with gasket and wear pad debris. there was also lots of debris in the depression of the pan which i'm guessing that while the engine was running was getting sucked up into the pickup screen and blocking the flow even more. i decided to inspect the oil defoamers AOS as while i was in there. I was surprised to find that the tube going to AOS on cyl 4-6 was completely blocked full of plastic wear pad debris. about 3 inches worth of blockage. cleaned all this out and reassembled. the opposite AOS was clean and clear." This is very interesting to me as my engine exhibits the same symptoms. The oil defoamers are accessed from the oil pan? I'm definitely going to check them on the next oil change!

Cool that you chased this to its end. I was thinking "scored cylinder" as I was reading your account of events. Glad I was wrong! thanks for sharing. Another data point to file away in my brain.

I wish I would have seen this post two months ago when I had my motor out and upside down on a stand with the sump plate off 🙄... oh well, still looks pretty simple from under the car... and the parts only cost about $100 for both !

renn101.jpg this image is of the inside of the oil sump you can see the two black cylinders on either side of the sump those are the defoamers. i guess the oil is pumped trough them when it returns to the sump and it spins the oil through the cylinder to remove air bubbles from the oil. the tube that you can see that is going upwards at a 45 degree angle from the center of the engine, that is the tube that was completely full of debris. the defoamers are only held on with 2 bolts and once removed they actually come apart into 3 pieces, so they should be very easy to inspect. while you are in there i would also take your oil pickup tube off and inspect it closely, as even after picking out all the larger debris i took the tube off and getting it out into the sunlight i was able to see a lot more debris that was stuck in other parts of the screen. i hope this helps. when i was searching for info on the AOS/defoamers I was hard pressed to find anything online or in the forums.

Great post. Thanks for sharing your findings. It's nice to see your persistence paid off. Thanks for taking the time to write it up - adding to the searchable knowledge base for all of us. You must be overjoyed to have finally sorted it out.

I really enjoyed this post. Not many here have the skills or confidence to do what you did. That being said, the first assumption when the M96 ticks is that there is a damaged cyclinder. Refreshing to hear that isn't the case. Enjoy the car!!

i hope this helps. when i was searching for info on the AOS/defoamers I was hard pressed to find anything online or in the forums.[/QUOTE] Great posts, thanks for taking the time. P.S. you may find more info searching "swirl pots"

Oh, I know exactly what and where they are - I just didn't think to check them while I was in there. I'm thinking that since my symptoms are exactly the same as what you described in your first post (even cyl bank 2... 4-6). It would have been so easy! There's info out there - most people call them "swirl pots" - if you google "M96 swirl pot" you'll find plenty of info on them. Thanks again for documenting this - good stuff!

Great post. Congrats on finding your issue!

Great Post! Quit your day job and start a Porsche Indy Shop

This was a great read! Glad you found a solution to the problem. And happy to hear that Leith Porsche in Cary NC helped you diagnose the problem. That's very reasurring given KrazyK's experience with this dealership. He bought a 2003 Porsche Cabriolet for high 20s only to have the tranny die a horrible death at an intersection just few weeks after the purchase. Anyway, thank you for contributing to RL community.

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I havent read about KrazyK and his transmission issues. I will try and find the thread. Im hoping the dealer helped him with the $$$ of the repairs. thanks for all the congratulatory remarks. I am still completely elated with the car now that it is fixed. Since its been back together, all Ive wanted to do is drive my 911 :

Here you go https://rennlist.com/forums/996-foru...ersection.html I don't think the dealer helped at all.

Great post, thank you! I'm going to add this 'oil pan gunk service' to my next oil change. Another example of how an engine tick may be solved for less than $200 bucks instead of $15,000 - $20,000. When the kitchen sink drains slowly you don't have to replace all the plumbing in your entire house. A concept many infected with M96 hysteria can't seem to grasp. Porsche 996 best sports car value on planet earth.

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IF this Defoamer issue is of interest - check out the upgraded units from the 997. Most of the good Deep Sump kits include them - for a reason ? If the cause of the ticking was oil pressure so low (partial blockage in oil pickup pictured previously) that some Lifters collapsed, there may be other problems. Oil starvation that is severe enough to cause Lifters to collapse is serious. For example , the lifter carriers may have become worn/scored.The dry ,steel Lifters running in soft aluminum alloy Lifter Carriers is not good.That mechanism requires high pressure to maintain the oil film between the carrier and the Lifter.It is that pressure that feeds through one tiny hole in the side of the Lifter to eventually reach the ball valve in the Tappet. If the pressure is too low, the tappet collapses under impact and ticking results.

First off thanks for the insight. ill look into the upgraded defoamers as i am interested in adding a deep sump of some sort. I did think about the lifter carrier being an issue the last time i had the cam cover off i inspected the carrier with the lifters in and out (especially the cylinder with the failed lifter. in the picture i posted above of the engine you can see that i made a small sharpie mark on one of the lifter tubes. this was the lifter that had failed. i noticed no play or signs of adverse wear on any of the carrier tubes. there were no score marks or areas of the aluminum that appeared worn. (Albeit i used no technical equipment to check the tubes). there was nothing that appeared problematic. And actually the oil feed coming from the head feeds all four lifters from the same feed simutaneously. so i dont know why i was having a problem with just that one lifter collapsing. this whole problem overall still boggles my mind especially the fact that my oil pressure was reading good/normal. I do notice slightly better oil pressure now but not significantly.

INA lifters are a bit of a mystery if you follow the Threads. Just replace the bad ones. I fitted 24 new ones in my rebuild. Several were bad immediately i ran the engine . A few others deteriorated quickly.Off with the Camshaft Covers . Subsequent testing of the suspects proved them unuseable. So I replaced all of them - again ! And I am not the only one to have had such experience despite clinically clean engine, correct oil and Lifters The measuring of the Lifter Carrier bores for unacceptable wear is hyper precise. Ovality and taper.

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And by "bad ones" I take it that they wont hold pressure/pressure up and the piston bottoms out?

Yes, But you need to make a test rig to be sure. I mentioned the procedure in a previous Thread.Basically use a drill press+tool to actuate the tappet.Measure the force to compress it a few thou.and compare with 'good' ones. Try to revive soft ones by submerging them in oil and operating them. I failed to completely resurrect any bad ones. Some would improve but only if they remained submerged(unrealistic) .Others never improved. There is something drastically wrong at INA with quality control in China. Others have had the same problem - some good/bad in every batch. Most of the 90k mile old ones were still O.K. They were Made in Germany.They look identical to the new ones but clearly they had much better q.c. then. Replacing all 24 lifters is not fun ! There is no official test for new lifters.I was unable to make any of the last batch of 24 fail in the Drill Press test - so here's hoping .... There is an odd feature of new lifters(not old ones!) that tick immediately after installation. It has been mentioned elsewhere. I replaced an entire set of new lifters because some were ticking immediately after installation. The replacements also had a few thatt ticked. After a few thousand miles ,they became quiet. My theory is that I had failed to completely fill them with oil prior to install. The residual air inside was the problem. With sufficient heat and oil pressure, the air was purged. . In my case, and with the benefit of hindsight, I should have run the first se of lifters for more than a few hundred miles before replacing them.(again). YEMV.

Thanks for the post. I started hearing similar symptoms on my 2000 C4 about 6 weeks ago. I was hearing the ticking sound once the engine was warm, and while idling at a stop where the engine sounds would echo off anything close by. The similar symptom of the ticking going away at idle as well. Just got the car back from the 60K service with no feedback on the issue. Another shop recommended I check what oil was put in the car against the owners manual recommendation. The last two oil changes used 5W 40 synthetic. Owners manual recommends 10W30 or 40, but no 5W with the summer temperatures in MD. I had 10W30 synthetic put in and the ticking has gone away. The opinion of the shop that did the 60K service is that the heavier oil is just masking another problem. The answer appears to be, "stay tuned". I will keep an eye on it, probably drop the oil pan at the next oil change and inspect, and in the meantime, just drive it and enjoy.

Thanks for the thread Nathan. I believe I have a similar problem with a 2000 Boxter S. The debris in the oil pan includes some metal, some plastic bits and some silicone rubber. The picture looks similar to yours. My question is: Can I replace the tensioner pads without removing the engine?

I wish I had read this before last week when I dropped my oil pan. I did an oil change and since the car has high miles (182k) and apparently on the original engine I wanted to check it out. No metal debris at all, and now I know that the few small plastic bits are my chain pads. I cleaned out the sump pickup without removing it, and didn't know to check the "defoamers" or swirl pots also.. oh well, pulling the pan is easy and I want to install an X51 baffle anyway. props to you for perseverance.. and thanks for sharing!

I can only say... Congratulations for your work... this is a great example of never giving up with a car you like!

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Yes they can. Lower the engine as much as possible. That said, the metal in sump would not be connected to the variocam wear pads. I'd be concerned about another failing component.

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Thanks Moburki, The metal has me worried too. Oddly the engine shows no codes and will still fire up. A real mystery. I have a sound/video recording which I took before dropping the oil pan, but it won't upload to this site, I will edit and try again later. The drive belt was removed so the sound is not from any external source. The sound is intermittent at idle and it is a loud rapping/clacking sound. I did not rev it past idle for fear of causing more damage. Gregg

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Several threads on here with those symptoms, many times without and metallic debris. The possibilities are numerous to say the least.. Good luck sorting it out!

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Thanks, Luckily, it is approaching winter here so I have several months to sort it out. Watch for more as I dig in. Gregg.