SingallZ

I'm hoping someone out there has had the same experience as me and has had any kind of resolution to this. I have an 02 C4S with a noticeably loud non-rithmic rattle that only appears when the car is warm and only after being driven coming from the bellhousing region. If you rev the engine over 1000rpm it goes away, if you drive it for a really long time it sometimes goes away.

I cut the oil filter and no metal (or anything).
There is no difference in rattle when depressing the clutch.
The car throws no codes and runs great
It has a new AOS
It has a new water pump, pulleys, and belt
I've replaced the chain tensioners (unrelated problem that is now solved)
I've replaced the tranny oil and it was free of debris.
I've replaced the IMS bearing with an LN bearing
I've replaced the throw out bearing
I've listened to the block with a stethoscope and can't hear anything that matches the rattle
I've checked the heat shields
I've checked the tourque on almost every bolt
I've replaced the pilot bearing
The OEM DM Flywheel didn't seem to have much play in it when it was out 4 months ago
I've taken it to my local dealer and they don't know what it is ("maybe able" to diagnose it with tranny out)
It seems to be getting louder
I've run out ideas and sanity

Help me Rennlisters your my only hope

Ahsai

Are you sure it's from the bell housing and not a rattling catalytic converter?

joe-1972

Did you do any clutch work on her?
I have a AASCO Light Weight Fly Wheel and matching Sachs clutch.
Sometimes when in Neutral I get a cyclical rattle... but it goes away when in gear.
I have been told that is very normal when going from the Factory Dual Mass Fly Wheel to a Light Weight set up.
Hope that helps you!

-joe

SingallZ

OEM clutch and OEM DM flywheel. Clutch is only 2 years old and is not warn

3 different people have been under it and everyone confirms it's coming from the bellhousing

SingallZ

I'm pulling the transmission today, my Porsche mechanic thinks this it might be the DM flywheel or maybe the LMS retaining bolt or flange bolt might have worked itself loose. So I'm bring him the flywheel for inspection and checking the LMS.

I'll post pictures and keep the thread going until I fix it or give up. Hopefully this will help some other poor bastard later

Ahsai

Makes sense. It's the only way to find out anyway. Good luck.

pordlanzer

Truth

AdamL86

I have the same issue. The rattle stuck around even after replacing the clutch and flywheel with OEM parts.

I've been told it's normal, but will be very interested to see what you find under there.

Good luck.

pordlanzer

Just for reference, still haven't opened her up.. curious too..
May be linked, maybe not..

https://rennlist.com/forums/996-foru...s-opinons.html

SingallZ

I haven't read your thread before, but I'm experiencing the same issues on shutdown. Never mentioned it because the sound at idle is much worse.

Update:

The clutch and flywheel are now out of the car now and it turns out it's not an OEM DM flywheel but rather a LUK DM flywheel. Also looks like the clutch was getting a little burnt on it. I'll snag a few pictures after I take it to the dealer.

Also the LMS bearing flange was leaking a little, this is very worrisome. Looks like my cam locks are going to get a workout.

AdamL86

I thought LUK is OEM. This is not the case?

SingallZ

Yup, my mistake LUK is OEM. Missed that in my Googling.

SingallZ

So I finally have a happy update.

I took the fly wheel in to the local Porsche mechanic and yup it was on its way out. I'm not sure why I hadn't noticed it when I did the IMS a few months prior, but the Porsche mechanic pointed out that it had been resurfaced, and that it had way too much play. When you rotate it there's a dead zone where you can move it with your thumb (about 5mm) before you even start to feel the spring. Apparently you can't resurface a DMF easily without the proper tools or you'll risk damaging it, I'm not sure why the previous owner would go for this.

In the end my options were put it back in, turn up the radio, and wait for the inevitable OR replace it. That said I've put in a new LUK DMF from Pelican and the rattle is gone, also the rattle on shut-down is also gone and while I had it out I was able to fix a small leak from one of the IMS cover bolts.

Over all I'm pretty happy with the car again. If anyone wants to see what a bad DMF looks like I'll post up a video later before I take it to the scrapper.

Ahsai

Congrats and yes, please post a video or photos if you can. Very interested.

pordlanzer

Thanks for the update! It always helps others in diagnosing their own problems.
I'm digging in soon to do the same operations, did you change anything else this time while you were in there?