Team SSR

I am a fairly new owner of a high mileage 944S. I recently completed all the usual tune-up stuff and belts/rollers/tensioners/seals...as well as installing a chip. I drove the car a few times and was really pleased with how much better it was running. And then it started to rattle. I thought it was a heat shield at first, because it came from the center of the car. I put the car on jackstands today and started the car to look (listen) under it. The noise seems to be coming from the catalytic converter(?). The noise does not change if the clutch is engaged or disengaged. It sounds like a large chunk of something blowing around in the converter. If I rev it up, the noise seems to go away - like maybe the piece of whatever is pressed up against something(?).
i would appreciate any ideas, or if anyone has heard of this before. I'm really not looking forward to pulling the exhaust off - it is good condition otherwise. I can not shake it by hand and replicate the noise.
TIA!

Mighty Shilling

sounds like you need a new cat as the core is broken....

Porsche-O-Phile

Probably catylitic debris, like he said. While you're under there, check the cat heat shield also. They're notorious for rattling also (four 8mm bolts IIRC). Just tighten it up.

Team SSR

Would there be any danger of this clogging the exhaust? I'd really like to be driving my car at least for a little while until I can get a new converter?

Team SSR

The heat shields seem OK - I can't make them rattle.
Thanks!

RMills944

nah, my friend had a jeep he drove like that for a year before we gutted the cat. You may feel a slight power loss, but it should stay running fine.

xsboost90

exhaust is easy to remove youd be surprised. sounds like the cat..

hey, tell that chick to get off your hood, dont want dents and such!!!

nine-44

There is a heat shield above the cat actually mounted to the body of the car. I've seen these rattle before.

Team SSR

It took several beers to get that chick on my hood!

It's still on jackstands... I'll double check the heat shields tomorrow. I'll have to drive "The Boy's" car to work in the morning ('84 944 n/a).

Macfreak007

On my Girlfriends Volvo, the cat material broke off and clogged the car up causing a serious!! loss in power, it is possible, you will also start feeling some heat in the shifter, center console area, as the cat heats up more than usual, I like the painted bumper pads, looks clean!

Charlie

My car was making a similar noise and I thought it was the catalytic converter or heat shield. I got under the car with it running, did not see anything loose but happened to touch the oxygen sesor and the noise quit. The OS was loose and rattling, tightened it up and no noise.

Porsche-O-Phile

Working on the exhaust of these cars is about as pleasant as working on an exhaust system can be - the holes actually line up, there's no rust, etc. Just drop the pipe and clean it out.

RMills944

It took me 15 minutes to put on my cat back including driving it onto the lift!

Team SSR

Thanks for all the all the help. After more investigation (and driving) I feel rather certain it is in the converter. It looks like I'll have to drop it at the "Y" end and investigate. I would like to do "the right thing" and put another converter back on (assuming mine is toast). I've seen several aftermarket converters at very different prices. Any suggestions of ones to buy or to avoid?

Team SSR

I got another converter from an '84 NA, which didn't fit, of course. But while I had mine off I looked through it...literally. It was a straight shot through the converter. I then pulled the muffler and attaching pipes off. I shook it around and a chunk of metal matrix came out about twice the size of a golf ball. So I put everything back together and I now have a low mileage converter and head pipe in very good condition for sale.