Navy'sporsche

I have been trying to nail down a noise in my early 85 944.

When I decelerate in 3rd and 2nd gear, between 3-2000 rpm I hear a noise coming from around the engine/bell-housing area. It's kind of like the chain sound when a chainsaw idles. If I give it any gas, it disappears.

I have recently done the "full" clutch job, new seal, bearings, etc..

Also since owning the car, a different torque tube and transmission has been put in for other reasons and no change.

Last tidbit: the noise doesn't seem to be as loud with the engine still relatively cold.

I'm going crazy on this one...

elzergone

Have you checked for loose heat shielding? I had a similar noise a while back and it turned out to be that.

Navy'sporsche

I have removed the CAT heat shield and the under-tray. Any other common shield culprits?

StoogeMoe

There is a black plate right around where the starter is.

Also check your motor mount heat shield.

John_AZ

Check the front wheel inner dust shields aka dust plate.

The noise may be transferring.

J_AZ

mytrplseven

Is the tranny shifting ok? Do you feel the symptoms in the shift lever when it's going on? I'm wondering if a rubber clutch might be down on the "get home tabs". Just spitballing here.

A.M.H

Like StoogeMoe said, there is the black shield that goes around the bottom of the bellhousing. Over time, it develops cracks around the two mounting locations/bolt heads, so it will have that sound you are speaking of. Mine did it to me, and it took me a couple times under my car to figure out what it was. I didnt see the cracks at first, so I had no idea that it was the culprit. It was actually by simple chance, that I was under my car inspecting for the sound, and my shirt sleeve caught the edge of it, and thats when I noticed the crack appear, from it pulling apart when my sleeve snagged it.

Fixed it, and no sounds since.

Legoland951

Was the noise present before the clutch job?

Navy'sporsche

Thanks for all the replies.

The noise has been the same before and after the complete clutch job.

I removed the black heat shield during the clutch job so that isn't it.

One thing to note: the noise isn't really that pervasive until the engine has warmed up. I thought maybe it was bad mounts that were causing a misalignment between the engine and the rest of the drivetrain. Maybe it's the motormount heat shields.

Keep in mind: the noise completely disappears the instant I put on any throttle and reappears if I let off throttle and the engine coasts down 3k-2k.

Legoland951

It sounds like a broken catalytic converter. The a piece of the honeycomb shaped catalyst most likely broke off inside and rattling around. Under throttle, it is probably pushed back against the remaining parts of the catalyst and probably impeding the exhaust flow.

Also, the factory cat does not have a heat shield attached to the cat. The only heat shield is attached to the tunnel and will not make a noise as you described.

whalebird

5th gear rattle is common on these cars. You will get the 'gear noise' upon deceleration in lower gears. I find that a GOOD gear oil helps a bit with this. Change your gear lube and be sure to use a high quality GL-4 oil. Amsoil is one of the best GL-4 oils available and is what I use. Do not use a GL-5 or 'meets GL-4 and GL-5 spec' oil. There are some here that have had good experience with various other oils, but the synthetics commonly available at most parts stores is GL-5 and does no good for your trans. I thought Mobile1 was going to ruin my trans just after putting it in. Use a dedicated GL-4 synthetic gear lube and see what happens to your noise.