I've been a list member for a couple of weeks. I've had a problem with my
'85 GL (145K miles) for the last five (plus) years.  My valves often will
make a very loud, hard, knocking noise for the first 20 (or so) minutes of
operation.  The valve noise is sporadic and seems completely unpredictable.
It might go a week or two and no noise.  It might make the racket every time
its driven for several weeks.  Often, a few miles will quiet things down,
but sometimes a 30 mile trip still hasn't done the trick.  As the years go
by it seems to more and more frequent.   I have tried different oil
viscosity's, adding valve lifter treatments, including "Marvel Mystery Oil".
Nothing really seems to help much.  I've been told by a VW dealership
mechanic that it is the bleeding down of pressure in the hydraulic valve
lifters and that adjustment won't help, an independent mechanic said it
would.  Any guidance or suggestions would be appreciated.

Bob Capra
Walnut Creek  CA