'87 944 S rear rattling

[fennercj]

Dear Pelican Parts forum members,

I own a 1987 Porsche 944 S (16V) fairly stock besides Turbo twist wheels. It does not have a catalytic converter, just what appears to be a resonator and a muffler.

Recently a strange noise started occurring when I push the gas pedal.
That noise is not existent at idling.
It is also not present while downshifting or during a certain RPM range.

The only time you can hear it is when I accelerate. During faster speeds, the wind prevents you from hearing it but it is very annoying and I cannot for sure say I know what it is which is why am I here.

Let me know if you need more info on the car. Recent repairs were a broken valve spring on cylinder 4, slave and master cylinder, reference sensor replacement, and brand new fuel pump and fuel pump relay.

The rattling sounds like it's metal and does not get better or worse after warming up. It is consistently present every time I accelerate.

Thank you in advance!

PS: Search function showed all kinds of rattles but I could not find one that describes my situation

Chris

[Gawernator]

Could you maybe videotape the sound? Where from the rear is it? Like a loose part rattling around type of sound? Or like loose hatch glass? Etc

[fennercj]

Download 20130506 122018.m4a from Sendspace.com - send big files the easy way
This was just recorded. Hope it helps get an idea. It does sound like a metal rattle. The heat shield looks to be in solid place. Anyone recognize it or have had a similar noise and knows how to fix it?

[Panzer909]

The only thing remotely similar to this was on my old E30 several years ago. A rear brake caliper clip was missing so the pad would rattle away while in motion. Not sure about the only under acceleration thing though. Just a thought.

[mike leborgne]

If the rattle is coming from the rear of the car, check the heat shield between the tail pipe and the gas tank. My car has a rattle when I accelerate or go up hill. Plan on pulling the old shield off later this week and fabricating a new one, I have tried to fix the old shield but the metal is to thin to weld.
Frenchy

[rmconner80]

It does sound like a heat shield to me. Get it securely on stands, get under the car and look around for anything contacting the exaust or any heat sheilds wrapping the exahust which are rusted loose. Watch out for any white fibrous padding (it's asbestos). On my car I've found it can be hard to tell where these rattles come from while driving: sometimes they may originate closer to the front of the car but may sound like the rear, etc.

If you don't find anything, try revving the engine with a helper looking around for the noise from a stationary position. Obviously just be careful if you are still on jack stands while doing this.

[Thekidwitha944]

I had a rattling noise in my 87 S, but it was a was coming from my trunk. Wound up being a part that wasn't secure that kept taping the glass of the back window. It drove me insane XD