Might want to pull the oil filter and inspect before any more testing.

Plus 1 on the oil filter, also...if you don't have a stethescope, a dowel rod will work just as well (1/4 to 3/8 in diameter).

Have you taken your interior engine cover (behind the seats) off as well as the top engine cover? In listening to the video it almost has a failed bearing from a steering pump or AC unit...just a guess. Fingers crossed for you it is something minor and fixable.

The AC is off. I hear the noise when trying to start the car, and then again when trying to accelerate the flywheel. I do have a stethoscope, but the noise is too intermittent to fin using this method I think

Try removing the serpentine belt, that way you can eliminate the AC compressor, power steering pump, alternator, water pump, and idler bearing. Be careful not to run it any longer then needed to diagnose the noise with no cooling.

Just a thought.... what if you pulled the spark-plugs and rotated the engine by hand.... listen/feel for any roughness or rubbing. If there is some then pull the serpentine belt and rotate again. Like Eric G mentioned could be a bearing on anything connected to the engine. Maybe focus on those items closest to the driver side first. If you feel no rubbing without the belt then check all the items driven by the belt. If all that comes up negative then it possible the IMS sprocket moved during the IMS bearing install and is rubbing. If that happened then it's probably 'pull the engine time'.. :(
Wish we could help hands on.

Try putting on your old flywheel and see if the noise changes....

can't, don't have it anymore.... the machine shop resurfaced it, but then said it was bad. They still won't give it back without me paying out...

Here's a question:

What physical changes in the positions of various engine parts occur when the engine is under load (either accelerating or being loaded at idle by the clutch)? That will help me to narrow down the list of possibly interfering parts. I am also planning to slip off the drive belt to rule out any bad accessories. The motor was running / sounding fine before this whole mess (other than a cold startup rattle that I hear is pretty common on older boxsters)

Here is a real dumb idea. Are there any bolts that pertrude through the fly wheel hitting the engine block? Just another thought.

Thinking out loud... If a chain tensioner became hyper-extended and was stuck beyond it's normal range of travel due to movement during the IMS retro, would it cause a nasty noise like that? My brother developed a squeal on his 99 and it was worn out chain tensioners.

Mystery solved? Read on...

After running the car with the cam tensioners loosened with no effect, and with the serpentine belt off (no change here either), I pulled the flywheel and think I found the culprit. See pics below:

http://986forum.com/forums/uploads01...1345683326.jpg

Fresh nicks in the engine side of the bell housing.There were more of these.

http://986forum.com/forums/uploads01...1345683500.jpg
http://986forum.com/forums/uploads01...1345683601.jpg

These are closeups of the teeth on the backside of the flywheel.

The pics are not great, but I think that what they show is that the flywheel was off-balance and was oscillating under load, causing it to hit the case, producing an awful racket. The horizontal teeth on the backside appeared to be bent inwards a little bit.

The only thing that throws me off is that the noise did seem to emanate from the left cylinder bank, but it's possible that was due to acoustics within the engine compartment. I was never able to isolate it with the stethescope.

Am I justified in thinking this was the cause of all the trouble?

I guess I'll be ordering a new LUK flywheel and bolts in the AM. What a ********************show this whole job has been...

At least it wasn't the IMS sprocket... that's a good thing. :)

Black Box was it the fly wheel like you thought? I've got exact same sound and it's driving me crazy. Had serpentine belt changed today and pulleys checked no cigar. Mechanic thinks it might be the water pump but it's not leaking at all.

Even if the water pump is not leaking, it could still have faulty shaft / bearings....

Thanks Steve I guess it's a new water pump then. Needs to be done regardless I'd imagine been awhile hopefully solves the squealing.

The flywheel was not the problem. I replaced it, and still had the squeak. After spending more time under the car while an assistant revved it, I think it's coming from the left hand cam sprocket area.

Sorry to hear you still have the squeal. Have you considered it could be the water pump? Like I said earlier I have the same problem exact same sound as your video. Changed the serpentine belt and checked all pulleys still squeals. The shop that did it stated it seems to be the water pump but I didn't wanna pay to change it yesterday as they said its not leaking.

Curious if anybody else has noticed a squeal before changing water pump?? Seems to be quiet until car warms up as well.

It makes the squeal even with belt removed.

I've pulled my IMS cover off again, and with it off, with both rear tensioners off at TDC and with cams locked I see that the entire IMS shaft is cocked off at an angle.

http://forums.pelicanparts.com/uploa...1346209207.jpg
http://forums.pelicanparts.com/uploa...1346209226.jpg
http://forums.pelicanparts.com/uploa...1346209249.jpg

Could this be related to the noise?

Ouch! After the IMS retro-gone-bad fiasco I had a feeling it might be fecked. I'm not sure if this can be repaired without splitting the cases. Ever considered a nice used 3.4L? :)