The o-rings at the top of the cylinder do very little to keep combustion
gasses out of the cooling system. The real failure is the gasket between
the cylinder and the head. The engine at some point may have over heated
or for some other reason the cylinder studs lost their preload,
(tension, stretch). Re-torqing the heads may help, but as you suggested,
a passage may be burned in. A leak down test may show if one or both
heads need attention. A head gasket job is in order.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of zolo
Sent: Sunday, July 11, 2004 1:30 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Bubbles, bubbles...

Hi guys,
This morning a friend woke me up to check his car.  His water was
overflowing from the overflow tank.  When it cooled down, all the water
has been sucked back to the engine and still some were missing.  I
proceeded to bleed the system but I knew something must be amiss.  In
the process I noticed that bubbles were constantly coming out of the top
hose of the pressure tank and I traced it back to the right cylinder
head direction.
The question is; what is this phenomenon and what is the remedy?
Zoltan
My guess is, that the top O ring of one of the cylinders of the right
side head is leaking through because the head is not flush with the
cylinder and now it is probably already created a passage that won't be
closing with the retightening of the head.  The car is 13 years old.
Yes, it is a '91 model which sound like 2005 to some of us, but it is an
older car now and all the syntetic gaskets have aged in it.  In this
case the engine would need a whole gasket change in my opinion.