On each of my buses...I prefer to use Hylomar on the valve cover gaskets.
Well... I haven't done them on the 91, but have on the 71 and 62...  Make
sure both surfaces are nice and dry and clean, smear some hylomar on the
valve cover, seat the gasket in the valve cover, and then smear a little on
the gasket.  Don't put a ton on, but don't be scared to use it.  Then pop it
on the head.
This coupled with a good strong bail seems to do the trick.  I haven't had
leaks for a while now.  Before I did this I used to just put it all together
dry, but they would usually leak not long after I put them together, and
using silicone or other sealants like that makes it a PITA to get the gasket
out when it comes time to change them.  Hylomar never solidifies.
I bought a new mexican engine a year ago (Type1 engine) and the case halves
were sealed with Hylomar along with a few other parts of the engine I
believe.....no leaks yet.

Isaiah

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM]On Behalf
Of Mike Collum
Sent: Tuesday, October 30, 2001 10:50 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: valve cover gasket replacement

>From 1968 to present, on both aircooleds and wasserboxers, I've just
smeared wheel bearing grease on the gasket surface of the valve
covers ... then on the gaskets themselves once inside the covers.  They have
always stayed in place and I haven't had any leaks.

Mike
'84 GL "Mongo"