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The car is a 92 ss 4eat with 170k, last week it started making a very bad noise. If it revs to above 5000 +/- and the throttle is released quickly, a loud metalic grinding noise. It happens in neutral or drive. I also noticed there are some metal flacks in my coolant (I just changed fluid a month ago) this may or may not be related. I can't tell where the noise is coming from.
Has anyone else herd of this?

Thanks in advance
Troy

Metal flecks in your coolant? That doesn't sound good. Id check your oil too. I'd drain it and look for metal flakes in it and in your oil filter. I'm not sure what your problem is but it doesn't sound good. How does the car behave at lower rpms?

The car runs great before and after the noise.

Does the sound only happen when you snap the throttle shut? Maybe it's a heat sheild rubbing against something when the engine rocks on its mounts?

Of course, that wouldn't explain metal in the coolant... I'll second Matt's suggestion of examining the lubrication system as well.

Did you drain the coolant to inspect it?

Not sure, but it could be an exhaust heat shield, or just a missing bolt in the exhaust. When i bought my car, it would make a nasty metallic noise at higher rpm's. (not sure if it's the same noise as yours) I figured out that a bolt was missing that held the exhaust to the body of the car. After replacing that bolt, the noise stopped.

Also, for the metal flakes... Don't those cheap coolant system leak sealers have metal flakes in them?? It could be that the previous owner (depending on how long you have owned the car) put some of that crap in there... Are the flakes still there? If so, did you flush the system really well?

If they are still there, I might drain the system and flush pretty good, hopefully you can get ALL of whatever is in there out. Then fill it up, drive it around and see if the metal flakes come back.

Good luck

Andrew

Thanks for the reply
I took it to a Subaru master tech this morning and he seems to think it is the flex plate between the engine and the flywheel, but he also said it could be a bad catalytic converter.
About the metal flakes he said the bearing in the water pump could be rubbing against the block, but said it is really noisy when that happens. I thought I flushed it out pretty well but I will flush it again and watch for more flakes.
If it is the flex plate, how hard is it to drop the transmission?

Thanks
Troy

Oh yeah, that's actually a good thought about the stop-leak...

Transmission removal was recently discussed in this thread about clutch work:

http://bbs.legacycentral.org/viewtopic.php?t=16502