Hey guys, I have posted this on Pelican a million times but Im asking you guys to help. Here I am agian talking about that GOD DAM rattle I cant find.
Today I got out of work around 1:30, so I figured why not try to find the rattle in the P-car, I set it up on jack stands and had my dad blip the throttle between 3500-4000rpm while I ran around trying to find this stupid rattle, First I checked for exhaust leaks, Found none, Then I checked all the heat sheilds on the P/s of the engine, none where loose and none where rattling, Then I checked to see if the shift rod was rattling, agian found nothing, I removed the shift boot to see if it was something in there, agian failed to find the rattle. I have no idea what it could be, Its not the drive tube because my car only has 86,000 miles on it and the noise is the same if the clutch is in or out. So here is a list of what I dont think it is

1. not the heat sheilds on the motor
2. not the shift rod
3. not the drive tube
4. no exhaust leaks
5. exhaust is not rubbing on anything
6. no baffels in exhaust are broken.

Agian the noise happens between 3500-4000rpm mostly when you let off the gas pedal, The rattle is A high pitch rattle sheet metal sound. It started making this rattle noise before I replaced my exhaust. It is loudest from the middle of the car near the bellhousing. Guys its driving me crazy PLEASE SOMEONE HELP ME!!!



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fast924S, my guess is the heat shields above the exhaust pipe, right behind the catalytic converter. They have small bolts (8mm, IIRC) that come loose. have you had a clutch job done recently?

Anyway, raise the car again and get under there with a ratchet and tighten them up. The noise will go away. At least it did in my case with the 83.

 

I think its just one of the issues with bursch headers and test pipe. I got the same rattle when i had mine one, which immediately disappeared once i put the OEM exhaust on. One of the problems with really thin steel...

 

Just a thought. Are all the 10mm bolts in the belly pan? There are 2 in the front under the lip, 1 on each side behind each front wheel and 3 on the crossmember. It these arent in tight, or if they are worn and rounded out they will rattle like a *****. I have but some rubber washers on mine and she's much quieter.

 

Serge944, I had the rattle noise before I replaced the exhaust, I also dont have a cat right now, Chris 924s which 10mm bolts are you talking about???? I havent had a clutch job, but I will be looking under there again soon, Thanx guys, I hope I can get rid of this noise, I hate it.

 

The belly pan.. the 924S has an aluminum belly pan to properly channel heat thru the engine bay and protect the bay from water and road junk.

If you have ever adjusted a PS or AC belt tensioners, you probably have taken it off to get to them. The front 2 (by the chin) are held by captive nuts. The other 5 are threaded directly into the body (2, 1 by each shock tower) and 3 in the rear dirctly into the crossmember that supports the engine mounts and engine.

 

WOW, ummmmm I think I might have a problem... I dont have this belly pan you are talking about, Maybe the guy who had it before me lost it. Is it bad that I dont have it?? Do you have pics of it??

 

You might check to see that all of the exhaust flange bolts are tight. After a recent clutch job I had a nasty rattle. Two of the six bolts were not tight, but I had no exhaust leaks. One bolt tightened right up, and the other snapped as I was tightening it. And I forgot to tighten the oxugen sensor, that was probably most of the rattle.

 

fast924S, it's better to have an engine protection pan than not, but you shouldn't get any rattles from not having one.

As for the exhaust heat shield bolts that surround the catalytic converter and exhaust tube, I believe they're 8mm and you need to tighten them well. Like you, I chased this "off throttle rattle" for a long time until I tried this and it worked.

 

I dont have one either...i kinda misplaced it when i was changing my engine. Its not a big deal in my opinion, unless your cars lowered and you like to scrape speed bumps.

 

The aluminum belly pan is as much for channeling air properly through the engine compartment as Chris said as it is a debris sheild as Serge commented. It may not be a big deal to run without, but I recall a thread from about three years ago or so where several people commented that they noticed higher engine temps when running without it.

IIRC the fasteners are M6 (6mm) with 10mm heads

 

Fast924S,

Did you ever find a fix for this?

I had bad vibrations/rattle/resonance when I bought the car last week. Fixed it by taking the straight pipe out and putting the cat back in. Also tightened the 4 bolts on the cat heat shield. (even though the heat shield seemed solid, this helped a lot). Between these two, 90 % of the rattle is gone.

But, still have the same noise, only when I come off the throttle and decelerate through 3200 RPM. Sounds like your description. Were you ever successful with getting rid of the noise?

 

Nope I still have the hissing rattle on decel like you notes, I gave up looking for it LOL, but I am soon to swap out my straight pipe with a high flow cat, Ill let you know what happens

 

Although you have dismissed the torque tube because you have low miles on the car, I think that is where your problem lies.

First sign of torque tube wear is front bearing noise. It sounds like a hissing and is most noticeable on deceleration. It's almost like the sound of a supercharger spooling-up. Saying that, I had that noise for almost two years and lived with it with no ill effects until I had time to do the tube rebuild.

 

I had a very similar noise in the same RPM range that drove me insane for 4 months. It was tracked to just one bolt. It was one of the pinch bolts on the torque tube/transaxle coupler. It had that weird sheetmetal sound too, so I never thought to look there. But that was all it was. I hope your's is that simple.