Vibration/Rattle sound when idling
 

Hey there I am a new owner of an 86 944. Learning Very quickly that I will probably be working on the car almost every weekend. I have had the car for just over a month and a half and have already replaced the steering rack, bearings and valve cover gasket.

Now I am hearing another noise. When idling regardless of being in neutral or not i am hearing a metallic vibration/ rattle. If you were to take a pan, place a bolt on it and place it on an engine, the resulting sound would be similar to what i am hearing.

If i rev the engine it will go away, and the sound occurs both when the car is cold and after i have driven it for awhile.

It sounds like it is coming from somewhere under the car near the bell housing or gear shift.

Does anyone have any idea what this could be? I am going to try to get under it later this week, but i would appreciate any suggestions on what i should be looking for.

I had a similar experience with mine a few months ago. Ended up being a loose O2 sensor.

Pop open the hood, and move around to the side, standing by the passenger side front tire. Follow the exhaust manifold down and you'll see it. It's a cylindrical shaped, 1 inch in diamets, screwed into the exhaust, sticking straight up. there should be a single wire plugged into the top of it.

To tighten it, you'll probably want to raise the front end and approach it from underneath. Unless, of course, you have arms as long as Shaq's! ;)

Randy

haha - good luck. It took me 3 months to get all my rattles taken care of. Most of them were heat shields - the biggest one was the plate shield that's right under the exhaust manifold and oil filter. I ended up taking a big ass screwdriver and pushing it down away from the exhuast pipes and it fixed the biggest and last one.

The other culprit was the piece that fits on the split pipe right next to the oil pan and right under where the wastegate is. Those tacks come loose and that thing rattles around all over the place. I took a cutter tool to it and just ripped it off of there. Be careful though - asbestos is inside of those!!

Have fun!! No way anyone on here can tell you exactly - you'll have to put it on a jack or even better get it up on a lift a little and just listen for them and hunt them down.

+1
that's the classic heat shield rattle.
a pain in the rear to take out, tack weld (easy part) and re install with the engine in the car.

i just noticed the location that you said the sound is coming from...

in that case, it's probably a exhaust mount. Could be that heat shield I was referring to - but could very well be a rubber flange on one of the exhaust mounts is gone and something is banging around down there.

That 'bolt on a pan' though is exactly what that heat shield sounded like to me and it would come and go depending on the rev/frequency of the engine. Mine wouldn't rattle around at idle, but I could work the gas a little bit and get it to stick right where it would maintain a rattle. Very annoying...

I had a similar problem, ended up being the screws at the end of the headers. Some bum thought it would be cool to just leave a rusted bolt loose.