[s-cars] front crank seal (aka crankshaft seal, main seal)

[Richard J Lebens]

My experience with crank seals;
 
I never changed one on an Audi but am getting ready for the second timing belt. 180,000 miles (Could be required?).
My experience with V8s is the seal wears a groove in the shaft and when you put a new one on the surface never lines up with the old grooves or virgin surface and they leak.  Luckily in this case you jest get a sleeve pressed on the balancer.

----- Original Message ----
From: Huw Powell <audi at humanspeakers.com>
To: Ben Swann <benswann at comcast.net>
Cc: tedebearp at yahoo.com; s-car-list at audifans.com; quattro at audifans.com
Sent: Thursday, March 29, 2007 12:47:15 PM
Subject: Re: [s-cars] front crank seal (aka crankshaft seal, main seal)


> My experience with the front crank seals after having removed and replaced
> several is that even at 150K miles they typically show no wear and actually
> look new.  IMO there may be as much risk in replacing one, especially if you
> don't pull the carrier - in this case the pump, than if you just leave it
> alone.  If it isn't leaking a drop and the area is indeed bone dry, you are
> likely good for another belt change.

> I'd appreciate any feedback even if to the contrary - I certainly don't like
> to do jobs twice.

I do have an opinion or two about this... first, the reason we 
"routinely" replace that crank seal when doing the TB/WP job is that 
it's an eight dollar part that takes several hours of labor to get to - 
and while all these parts are off, it's easy to get to.

That said, what you are saying makes some sense - the tough part for the 
amateur (at least) is deciding if that seal is good for another 60k 
miles/5 years or not.  So I would suggest that on any "unknown" engine, 
ie, the first tiem you DIY the job, you should replace the seal. On a 
"known" engine, ie, one you did 60k ago yourself, perhaps leaving it 
alone would make sense.  I know I sure wouldn't want to have to replace 
one "between" TB changes.

What is the "expected" lifespan of that seal?  I know that years ago I 
had to have the cam seal replaced on my coupe (at 150-200k or so).  I 
suspect failure is a bit random, but I might be wrong.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/
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