What's this noise? Bad clutch...again?

Can't figure out what this noise is from my 2002 996. I have been having trouble with a clutch issue involving this noise from the bell housing area. I have posted here before about this but all previous suggestions have been tried without success. I am attaching an audio recording of the noise, which comes on after the car warms up and is idling in neutral, and goes away when the clutch is depressed. This has been a frustrating process since I have so far spent more than $5000 on trying to fix this issue. The car runs great, but ignoring the noise in the past eventually led to a clutch failure. I have had the clutch kit, flywheel, and throwout bearings fixed about 3 times each by both the dealer and a well-reputed indy. Could this be an issue with the slave cylinder for the clutch? None of this is making any sense.

Could the release lever be involved somehow. Maybe bent? Do you only hear it at idle or is it present at other RPMs. I would guess so. It might be worth bleeding and then if no success perhaps replacing the slave cylinder, maybe it isn't fully retracting when you release the clutch? Not sure of your MY but you can get a new slave cylinder for about $110 + shipping. And then bleeding is fairly straight forward, there is a DIY on renntech and pedrosgarage on bleeding brakes an slave cylinder.

I can only hear it at idle. I'm assuming the noise is still there while coasting in neutral but it's difficult to hear over the road noise. Also, I can't be sure if the noise is there when in gear, again because of the engine noise overtaking it. But I guess it could be there while in gear. I recently had some body work done on the car and changed out the flywheel again. The mechanic said he would change out the slave cylinder as well, but now that I'm checking my invoice, it doesn't look like it was itemized. I may have to give him a call to see if that was done. Also, I asked my indy about the slave cylinder and he said that it was not related to this problem. I'm willing to entertain that possibility again.

Throw out bearing and or bent finger on pressure plate. My guesses.

It sounds like he had those replaced 3 times already???

Gearbox mainshaft bearing? I think that I have read about others that had bearings go bad on the transmission.

Really sounds like something going on with the flywheel or trans input shaft (those are at rest when you step on the clutch). It could be also something with the pressure plate cover. Could it be that one of the bolts holding the pressure plate too flywheel is too long and scraping on the bell housing or engine case? Sometimes when assembling the clutch I'll use extra long bolts to draw the assembly together and trade them out for the stock bolts when fully assembled. or one of the bolts could be backed out a bit and scraping. Does it make this noise when you're driving?

I don't think it's the slave or throwout assembly because when you're putting the force on them (when the pedal is depressed) them they're silent.

when they pulled this apart were there any scrape marks on the bell housing or under the flywheel on the engine case? maybe some of the bolts on the IMS are backed out and scraping on the backside of the flywheel? When you're making noise like this there's going to be some scraping/wear somewhere. what about the old parts (removed broken) can we see some pics? if they're trashed they will certainly show clues as to what's going on. Please don't tell me the shop threw them out.

Thanks for all the great suggestions thus far. And yes, virtually all elements of the clutch kit, flywheel, bearings, etc. have been replaced at least 3 times each. Everytime, the noise kept coming back. I'm attaching a photo of my clutch plate when it failed over a year ago. The central shaft splines are completely sheared off. My indy said that there appeared to be nothing wrong with the transmission itself. He also looked at the flywheel and throwout bearings at that time and noted that everything else looked good with normal tolerances on the flywheel. After searching extensively in the forums, I came across a post that noted a "ticking clutch pedal" and described the phenomenon just like my issue. However, he didn't mention noise in the bell housing area. After replacing all other elements of the clutch system (including slave cylinder), he still had the noise. That is, until he changed out the master clutch cylinder. Could that be? That a faulty master clutch cylinder is the culprit? How would it fit this scenario? As an additional piece of information...I can sometimes make the noise go away if I play with the clutch pedal.

Here's a picture of my flywheel that was replaced this last July.

Wow that does not sound good. I recommend you talk to Tony Callas @ Callas Rennsport in Torrance CA & get him to listen to your video. He writes the tech articles for Excellance magazine & PCA newsletter. I'm guessing transmission related cause. It is worth the effort to have flywheel & pressure plate balanced for everyone & especially you.

Thanks for the referral. I take my car in to Johnson's Alignment for brake and alignment issues. I used to see Callas Rennsport in the same strip mall, but didn't know anything about the shop or Tony. I will have to take my car to him for a listen.

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Hard to believe that the same hardware was replaced 3 times absent any clear indication it needed replacing. I wonder if someone's not stringing you along? You say the car runs great. Just to be sure there is no issue starting the car moving from a stop? The clutch engages smoothly, with no grabbing, no noises? With the engine idling and the clutch depressed you can select any gear without any difficultly? Once underway with the engine/drivetrain up to temp hard acceleration in gear does not produce any signs of clutch slippage? And shifting once underway is without any drama? If you can answer "Yes" to all of the above, then I can't see how the clutch hydraulics or clutch linkage can be the problem. Now it may be the linkage is not routed right and a part of it is making contact with the body or an exhaust or bellhousing. Something. Has anyone been under the car when this noise is present to view the various clutch and shifter linkages for any signs of movement? Have the engine and transmission mounts been checked? For the clutch's splines to go away like that could be explained by a bad heat treatment of the clutch splines. They were left 'soft' and could not take the load. They want to be quite tough, tough like a gear. In this case a manufacturing defect is to blame. Or there was excessive drag as the clutch moved from engaged to disengaged which wore the splines down until they could no longer hold. This suggests a mechanical problem. For instance, a misaligned transmssion (or engine) could account for this. But I can't imagine how the transmission and its input shaft and bearings could long stand this without signs of trouble. Well, maybe the noise is the sign of trouble. The above is why I asked about the engine and transmission mounts. Absent a clear sign something needs to be replaced and I am not sure there is a clear sign, I can't believe replacing the clutch slave cylinder called for? For me, at this point if that were my car, I'd want to be under the car with the engine running, idling and someone in the driver's seat and able to work the clutch and shifter and see the clutch hardware move, watch if the engine or transmission moved about. What I saw, or didn't see, would help me decide what to do next. Sincerely, Macster.

Macster, Those are terrific questions and suggestions. The answer to all of your first set of questions is "yes". There does not appear to be any slippage or difficulty in shifting. All gears are smoothly engaged, no stickiness. The car takes off great. The only thing I personally have not done is get under the car while idling. But I would have to think that my indy already did that and did not find an external problem with the linkages. The Porsche dealer that originally tried to fix this problem definitely did do this and reported no problems. Engine and transmission mounts all look good, and the main transmission crankshaft is centric with no evidence of wobbling, catching, or bend. I had the noise going on for about 1 year until the clutch failed and the splines were found to be sheared. We (meaning indy) chalked it up to bad manufacturing but of course, Porsche did not see it that way. I'm wondering with the ongoing noise (whatever the source) for that long eventually wore down the splines??? I think my next move will be to swap out the master clutch cylinder, since this is the only item that has not been addressed. I can't give you a reason why this would work or not, but I'm desperate to get this fixed before I get stranded again.

Slave cylinder for clutch. Mounted above transmission. Master cylinder for brakes. Mounted in front trunk. 997_rich and speed rII might be on to something. Where is the evidence of the clicking noise when everything is pulled apart. There is probably going to be some rubbing somewhere. On a sensor, on the bell housing. Or inside of something. You need to find it. +1 to Macsters comment, have the car on a lift someone operating it, and look for yourself where approximately is the noise coming from. Since you've had it in the shop for so long, why haven't they provided this info.

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I'm with you on that part being highly suspect. The symptom of the noise not starting as soon as the pedal is released which could be it taking time for friction to bring the associated fresh to spinning shafts parts to start their noise making. In the video it was almost like double shifting to bring the shafts noise making part be it bearings or spindle to speed so that it would transmit the sounds through the casing. Not that I have broken everything there is to break in my 40+ yrs of cars Possibly the main clue of diagnosis can be found in the noise not being present during load on driving. Maybe maybe not. But more possible is the in our face clue of the already replaced parts hint hint wink wink. What would throw the clutch out of wack? Er uhhhh.........darn I forget what could do that. Oh well I'll take my senility some place else........like the dealership since my new engine is in town waiting for new transmission mounts......I didn't break it, it just broke

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If you have 100% confidence the dealer/indy did what they said they did then given the fact other hardware that is reasonable to suspect has already been replaced, and given the cost of doing this, the relatively small additional amount of money it would cost you to swap out the master (I thought you said "slave" in the earlier post?) is not a bad idea. I hate to throw parts at a symptom but sometimes that's the right thing to do. It also gets you or someone up close to the engine/transmission and maybe something will be spotted that others missed. Sincerely, Macster.

Let me add in a separate message that along with looking at the various hardware, hardware mounting points, etc., listening via a mechanic's stethescope in order to as good as possible locate from exactly where the noise is coming goes a long way to helping one identify the reason for the noise. Sincerely, Macster.

Now that I have given more thought on this one, I'l bet that it's the transmission bearing. Misalingnment in mainshaft could eat the splines fast, allso it's hard to diagnose when the gearbox is out. There is always some "slack" in the mainshaft. I think that the noise is coming from the ballbearings running with out the gage/holder. Btw, would you be interested to sell that flywheel??

[QUOTE=speed rII;9122231]Now that I have given more thought on this one, I'l bet that it's the transmission bearing. Misalingnment in mainshaft could eat the splines fast, allso it's hard to diagnose when the gearbox is out. There is always some "slack" in the mainshaft. This is my guess also. Try calling California MotorSports & talk to Roger & send him your video link.

agree on the trans input shaft after hearing this. this will bounce around when there's no load on it. when there's load on it, it will push to one side and you won't hear the clattering. when the spline on the friction plate was trashed, nothing was done to the splined trans input shaft? how does it look? I'll bet when you remove the trans you can grab the input shaft and feel slight joysticking when you put force on it.

The trans input shaft splines did not appear to be damaged when we took a look at it. I did not give too much attention to the lateral play in the shaft when the gearbox was out. It didn't necessarily look abnormal or different from an input shaft without this noise issue. We were more focused on catching something that was causing the input shaft to maybe temporarily seize up. But we found that the shaft moved smoothly and without difficulty. All 3 mechanics have had assistants underneath the car look for any unusual wobbling of parts and there has been nothing too unusual. They all agree the sound is coming from the bell housing which is why the clutch/flywheel/throwout bearings have been swapped out so many times. However, they have found no other evidence of wear or scratching in or around the bell housing to identify the source of the noise. The funny thing is that there's no initial noise for 1-7 days following the replacement, and eventually the same noise is back. This last time, this noise came back as I was driving home with the car. With the exception of the Porsche dealer, I do think that the other 2 mechanics who have worked on this problem are knowledgeable and trustworthy. They simply can't figure it out and will not pretend that they know how to fix the issue. The noise (and vibration) is also very palpable in the clutch pedal when depressing it to a critical point (approx 1/3 the way down). Once past that point, the noise goes away. Also, the noise is not necessarily present when the car is cold. Only after 5 min or so of driving does the issue act up. I'm also able to make it go away sometimes when I push the clutch to this "critical" point and release it gently. speed rII - I don't know if I'm quite ready to sell the flywheel yet. I want to hold onto it until I figure out why I'm having this issue. But PM me an offer.

Macster - My mechanic doesn't think it's the slave cylinder or master clutch cylinder, but I'm with you on this one. I think trying to do a quick swap of the master cylinder may be an inexpensive option to possibly find a solution. I can't help but think that the hydraulics of the clutch may be out of whack, where the adjustment is not quite correct. I'm also not sure if I have a faulty master cylinder. I have read posts from others that they did note broken seals when they did the swap. Is there a good DIY out there on this?

My car started making the same sound yesterday! The sound only occurred when the car was in neutral, but as soon as i pushed in the clutch pedal it went away, and if I played with the clutch in and out it would stop making the noise even when in Neutral. I thought I could hear the sound driving in gear though too (I was at low RPM coasting). Let me know what you find! BTW. My car as 50K mi with original clutch/flywheel.

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Well, I didn't express myself very well, because I don't think the noise/symptom is the clutch slave cylinder or hydraulic system either. I only went along with your wanting to change these because doing so is less expensive than removing the transmission and possibly the engine and determining what is wrong. If the root cause of the symptom can't be determined from someone under the car with another person operating the clutch then I do not see a cheap/easy solution. My thinking is that someone with experienced eyeballs would spot something amiss and from this would at least have a pretty clue as to what's going on. Sincerely, Macster.

Point taken, Macster. I absolutely agree with you. My comment/decision was one out of desperation and not wanting to drop out the transmission again for something that still seems so uncertain. I will be getting the car over to another experienced set of eyes/ears before doing anything else. I think Tony Callas in SoCal may be a good person to take a look. Skotch13 - sorry to hear you're having the same problem. I think the sound you hear at low speeds is a type of growl as the engine is at the threshold of lugging. I don't think that's abnormal. I had that looked at as well, thinking it had something to do with the clutch noise I described. Other more experienced people have driven my car and note that it's a normal sound variant at that low speed. Also, if it were the sound of gears grinding you would see some metal fragments in the transmission fluid, which I have never seen in mine.

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Once again my view is if these parts that are breaking have been replaced multiple times it's something else causing the failures. Then the sounds I heard don't sound like clutch caused noises and I'll elude to somebody else you listen to that is telling you to get a good listen to exactly where the noise is coming from with a stethascope. Kill the fricking beast. Sure the noises can be made by the clutch department BUT what is causing them to make that noise is what you have to focus on. The drummer appears to be from the input/trans side to me. Also those noises can also be made by gears and shaft in the trans. Good luck because you sure aren't geting any lately. Me either but who cares right.

One thing for sure is, something making that noise WILL be leaving marks, be it wear marks or leaving shavings around etc. I can see why the clutch assembly would be replaced, I cant see why it would be replaced several times if it never solves the issue. Also, the bellhousing is a part that its easy to resonate to, and the sound may seem like its coming from there, for that reason, not to say it isnt however. When I have clutch issues I went to extremes... I cut a section out of the bellhousing, making an inspection panel in effect, then I could actually see the issue occurring, put light in, video it all that stuff. Not suggesting it here, but one thing to consider if you are at your wits end. It bet pulling it in and out a dozen times for sure...

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I think thats impossible. I cant think of any way the slave cylinder wouldnt retract since the carrier bearing is pressed by the pressure plate fingers forcing it out. The shaft at the end of the plunger would have to get stuck somehow which I just cant see ever happening.

Soooooooo how's the car doing? Put a bullet through the crankcase or have a good porsche tech look at the history and get a listen?

Any progress on this one?? Just found out that my transmission makes sometimes sound like this. Not as loud and not all the time. Just got 3k km after the engine rebuild, so now the transmission need's rebuild... Or maybe change to M3.... :P

Oh no... well at least the engine is running strong.

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Yep. I can't hear the noise if I stand next to the car, only when I was under it. In the grease pit...

Hi apanossi, Did you make any progress regarding the clutch noise in your 996? I would very appreciate if you let us know the solution that worked for you, in case you already find it. Thanks a lot, Luis.

3 months and no real results? I'd dump your workers and find a dealership or race team that's found all the odd screw ups already and knows the sounds and can spot the problem from reviewing your symptoms that go along with all the repairs tried again and again. One trick you could try but not want to is not push the coutch in and try putting the car in gear while its running to get close to actual gear engagement. You don't want to grind gears but get the syncro's working and add some change to the shafts to see if the noise stops. If the syncro's don't allow getting messed then I'd try getting them started with the cluch in slightly or all the way before gear engagement and see if the nosie changes and how it changes. I'd try different gears and reverse. I'm not sure if there are two seperate shafts for odd and even gears or what in there but you do have to find the problem. Sorry to hear its been a long haul of failures. Maybe get fond of modern rock and roll that sounds like that racket?

Sorry guys. My car was rear ended at the end of December and it's been in the body shop getting work done since. Total of $18k damage. Insurance company wouldn't salvage it. Anyway, mechanical is finally going back in the car. I was going to explore the possibility of the trans input shaft. I'm not sure if i'll end up with an answer on this one. I'm not sure I want to throw any more money at it. But if there's clear cut evidence this last time, then I will definitely post the solution.

Wow thats bad on the rear getting thrashed. I hope you are doing OK. I think most insurance companies allow disputing the way claims are handled. I don't think anybody but Porsche is the right people to handle repairing major damage like yours. That alone would probably throw the cost of repair over what the insurance considers totalled.

Hi apanossi, Sorry your car was damaged; I hope you will enjoy it again after they fix it. Thanks for sharing the solution if you finally get it, Luis

Ok guys. At wits end, I decided to get a new transmission to solve this problem. Well, I'm happy to say that the problem has been solved...so far. The old tranny is on the way back to Porsche for diagnosis. This has and continues to be a mystery to me, but it is now clear that the problem seems to have been with the transmission itself. I'm not sure what would cause these symptoms mechanically within the transmission, but I'm back to loving my car again. I know it's a bit anti-climactic, but I thought I would post what seems to be the solution to this issue thus far. Hopefully, I will get an answer at some point from Porsche on this and share it with everyone.

I hope it was your transmission. I had a rebuilt one put in because the old one was 'noisy'.... nothing like as noisy as yours and not even a pulsating noise as yours was. Mine was just loud inside the car. With the top down (I have the cab) it was hardly noticable. Only with the top up and windows closed was it loud. Since the upgrade. The car is really quiet. Hope yours is a success.

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Really late to this thread, but if you still have a recording of the sound any chance you could repost it?