Tappet Problem - Help!

[parker@mprgate.mpr.ca (Ross Parker)]

Hi, all...

I have a nasty tappet noise in my 1987 Audi 4000S Quattro - Sounds like
more than one tappet, but it comes and goes... sometimes only at idle,
sometimes at higher revs, more prevalent when cold. Usually goes away
at higer revs.

The car's got hydraulic tappets. I've got the top end apart right now,
and, well, I'm a little confused with what I've found.

1 tappet out of the 10 (it's a 5 cyl) compresses (and rebounds) under
hand pressure. The other 9 do not. The center nub (that actually acts
on the valve stem) rotates freely in all 10.

Never having held a hydraulic tappet in my hand before, I'm not sure
which action (the 1 or the 9) is correct. I'd have thought that if I
had *9* tappets out of action, I'd have a lot more noise than I do, and
it'd be a lot more consistent. However, the nice action of the 1 tappet
that compresses just seems 'right' to me.

So... How should these suckers be reacting? Should they compress under
(*light*) hand pressure, or should they appear to not move at all (even
under extreme hand pressure)?

The oil passages in the tappets seem clear, and the top end is pretty
clean. No gunk that I can see (and I change the oil & filter pretty
regularly).

If the 9 are supposed to compress, any suggestions as to how I can try to
free them? They've been sitting in a pan of varsol for about 4 days now
(yeah, I know, it ain't a super-solvent...) but no difference yet.

I'd really rather not fork out the $350 (CDN) for a new set :^(

Any help would be MUCH appreciated!

Thanks,

Ross
--
Ross Parker           | KotHFJ '88 FJ1200, '64 Matchless G80CS (500cc)
MPR Teltech Ltd.      |     Who cares if Mikey doesn't like 'em!
Burnaby, B.C., Canada | "Lisp has all the visual appeal of oatmeal
parker@mprgate.mpr.ca |  with fingernail clippings mixed in"  --  Larry Wall