911Dave

I recently noticed that my 86.5 is making a suttle metallic sound that appears to be coming from the engine. It's very smooth and sounds like two metal discs sliding against each other. The pitch does not vary, but the volume varies with engine speed. I can't hear it when I'm driving unless the windows are down and I'm driving close to a barrier like a fence. It sounds very similar to a brake pad lightly rubbing a disc, but with a more metallic quality. The timing belt and tensioners were replaced about 400 miles ago but I'm not sure if this condition existed before that. No other recent changes to the car. It's not very loud but I'm concerned. It doesn't sound like chain noise. Anybody want to hazard a guess as to what it might be?

SharkSkin

Air Pump? Pull the belt off the air pump and see if it goes away. If not, pull the other belts off one by one(alternator belt last) until it goes away. Maybe one of these accessories had a marginal bearing, and after the TB/WP that accessory's belt was tightened enough to finish off the bearing. If it's not an accessory, maybe a timing cover was installed incorrectly or some other aspect of the TB/WP job was botched.

Mark

Also - check your forward exhaust system mounts...if they come lose, or get bent - they can make a similar noise...ditto with something that may be laying against the any part of the exhaust.

Louie928

Possibly the water pump impeller slowly grinding into your engine block. Get a mechanics stethoscope and listen in different areas of the engine near where the sound seems to be eminating. Compare to other similar engines that don't have the sound. It's not too uncommon for a marginal water pump bearing to go after timing belt replacement and probably increased belt tension. I didn't see where you also replaced the water pump with the T belt. Have you checked tension yet on the new belt? It's a little early at 400 miles, but you might want to look in there and visually check anyway.

jpitman2

Worn out front pad doing a metal to metal??
jp 83 Euro S AT 49k

911Dave

Sorry, I forgot to mention that the water pump was also changed at the same time as the TB. I checked all the brake pads and they have plenty of thickness. I'll try some of the things you guys suggested and see if I come up with any more clues. Thanks.