Rear main seal squeal

["Thompson Smith" <thompers@together.net>]

>Phil Payne wrote:
>> 
>> In message <362F504A.F52AFD3D@remdesign.com> Wallace White writes:
>> 
>> > At cold startup I've been hearing a screeching noise for maybe 30
>> > seconds or so; it's getting longer. The sound is coming from the
>> > distributor, it seems, though I don't know which part of it. Any BTDT's?
>> 
>> Does the screeching stop when you pull the dipstick?
>
>Bob Myers and Todd Young just asked me the same thing, saying that that
>would indicate that it's a leaky rear main seal. I haven't tried the
>dipstick test yet, but I will tonight. What is the relationship between
>the sound and the seal?
>
>- - Wallace
>  '87 5kcstq 150k

The screaching sound is most likely from a worn (hardened) rear main seal.
Believe it or not, once you button up the top end vacumm/boost lines, the
rear main seal on high mileage engines usally has formed a small grove on
the crankshaft (along with the rubber seal hardening) to cause air being
sucked into the engine at idle (high vacumm). The crankshaft could and might
shift a very small amount fore and aft to help stop the noise for awhile.
Try placing the Audi in reverse and go at a high rate, then nail the brakes
abruptly. Does the noise cease? After 172K mi I had the opportunity to
replace mine on my 1989 200tq avant. Drove me nuts. My throwout bearing
decided to disinegrate into rust and this was my chance to fix the annoying
main seal noise, resurface the flywheel, and install a new clutch kit. The
OEM clutch plate, stamped 11/88, could have done another 172k. This happened
1 week after I had a complete modified suspension rebuild. Now it drives
like it was new. Audis are wonderful cars!

Thompson Smith