Finished Clutch / IMS Job, now have scary mystery squealing noise - 986 Forum - The Community for Porsche Boxster & Cayman Owners

I was planning to return home tonight and write up my IMS experience for posterity. Instead, I find myself pondering a worrisome noise that started as soon as I fired the Boxster up after the job. To set the stage: I just replaced the clutch w/ sachs kit, pilot bearing, throwout bearing, clutch release lever, installed a low mile resurfaced second hand flywheel out of a wreck, replaced IMSB with Pelican / OEM type replacement bearing, bolted everything back up and torqued it all down. The noise is a high pitched squeal, sort of like a bad wheel bearing or belt. It only seems to happen under engine loading, but does not depend on clutch position or gear. I noticed it immediately when pulling out of the garage, giving partial throttle. When driving, the noise is only present when accelerating -- it goes away when I back off the throttle. I can also make the noise when not moving in two ways: Firstly, with shifter in neutral and giving it throttle, the noise is present while engine speed increases, but not when it is constant or falling. In gear, when I slip the clutch at idle against the brakes by using two feet I can produce a constant squeal. I did this while the car was on a lift while an associate poked around underneath. He seemed to think it was coming from the driver's side axle area. Some thoughts: It shouldn't be the IMS bearing (god help me if it is!) or serpentine belt because they shouldn't care about load, only engine RPM or rotational acceleration. It shouldn't be the clutch, CV axle, or wheel bearing because I can make the noise while stationary in neutral (by poking the throttle). It shouldn't be the motor/trans mounts or dual masses of the flywheel because of the continuous nature of the sound, which means it has to be something making full rotations. I am stumped, and scared. Please give any constructive input. I will try to make a recording tomorrow and will not be driving the car until this is solved. Thanks.

Oh, by the way car drives fine, clutch feels good, although it engages very low.

You received the wrong clutch disc, or installed the disc backward.. The center hub on some discs are thicker than others, even with Sachs we find inconsistencies in this area.. Been there.. I'd bet lunch on this.

I definitely put the flat side towards the flywheel, so maybe the clutch disc was wrong? If so, and thinking wishfully, will the clutch break-in period smooth it out? Will this account for the low engagement point?

I didn't know you could resuface the dual mass flywheel successfully.... who did the work on the flywheel?

I used sachs clutch kit k70290-01, which is definitely referenced as the right one for an '00 Box S. Feelyx -- the DMF was resurfaced by a local shop in Queens, they do them all the time for BMW's etc...

BB, sounds like Jake also said your clutch disk might be installed backwards. On this clutch disk, the center section is bowed out towards one direction. Which orientation did you install the disk: Bow towards the flywheel or towards the transmission?

Pilot bearing...? Does the pitch frequency increase when rev'd up..?

Here's video: Mystery squeal after clutch / IMS bearing replacement - YouTube seems to be from driver's side of engine.

Hi BB, For what its worth... I was told by a German auto mechanic here in So. Cal. that DMF typically are not machinable without completely being dissembled, machined, and rebuilt with new everything. He said it was more cost effective to purchase a new one. This fellow is from Germany and has been a Merc, BMW, Porsche mechanic most of his 60+ years. So unless the machine shop there in NY has a really effective way of assuring the flywheel is locked down and doesn't move or they rebuilt the whole thing I'd almost suspect the flywheel as being warped or as mentioned the clutch disc is wrong or is compromised somehow. As far as being backwards it's pretty hard to put one that has a dome on it in backwards. I would think you would notice it as soon as you attempted to install the pressure plate. I've only done one so I'm not an expert but just some thoughts... Good luck, Cheers

I have never seen a resurfaced dual mass flywheel that worked, and taking one apart is just not economically feasible, which is why they are replaced when they are no longer flat. Most attempts end up with an uneven surface or kill the elastomeric material and defeat the purpose of the dual mass. Jake has a valid point on the disc, some aftermarket discs are thicker in the hub area than the OEM units and cause no end to problems, which are often very difficult to diagnose. If it is not an OEM disc, or had not been checked against an OEM disc before installation, I would consider looking there and checking that flywheel for trueness as well......

a bad flywheel shouldn't cause the issues that I'm seeing though, should it?

At this juncture, no one really knows for sure what the issue(s) is (are); regardless of their basis in fact and experience, all suggestions are conjecture and nothing more. I have seen the exact problem Jake mentioned; I have also not seen a resurfaced dual mass work correctly. That said, I doubt the dual mass can make a noise, but I do know the wrong clutch disc can make all kinds of noises. In addition, I also know that if the car was in my shop and made noise after reassembly, it would already be apart to see why…………… It is not going to “heal itself”. You have work to do.

Yep, time to dig back in there or hire a new mechanic.

I dropped the transmission with the slave still attached. It seemed to be in the right place in the release lever. Sorry for the poor photo, but this shows the clutch disk with a bit of scorching near the the fastener. This probably occurred while we purposely made the noise on the lift. This is what the pressure plate looked like. The throw out bearing that I installed was for a 987 (pelican said this was the only one they sold) and I had to buy a new ball pin and release lever for it. This is the old OEM 986 pivot piece that was in there from the factory (or last clutch job). I left it in even though the new release lever didn't seem to have grooves for it. Maybe that was a mistake? I still don't know what was causing the problem, and am not sure if the clutch disk is still good... Not really sure how to proceed here.

New reality: It's not the clutch. I started engine up with only the flywheel attached, and it still makes the high pitched squealing noise when you poke the throttle, but only during crankshaft loading (acceleration in this case)

Also, as I mentioned before, the noise seems to be coming from the left hand cylinder bank.

I had to really beat on the ims shaft to remove the nut from the installation tool when I switched out the bearing, using pelican set screw method. I hope the ims cam chain sprocket isn't pushed too far in or something else that will require the case to be split!!! I am dead on terrified of this outcome.

Is there a safe way to get a stethoscope in there while making the noise?

Try turning the AC to Off. Maybe it's the pulley as it loads. Even the belt and other pulleys may be suspect? I also have a noise but it's more a whine than a squeal. Haven't had a chance to dig into it but the more I listen to it the more I'm convinced it's a hose sucking air and it goes into high pitch on high revs.