Yes, I concur with Brian. I had been dealing with this problem since last May, but the tank would back up only after sustained highway speeds. The giveaway was that the coolant temp light would blink for about five minutes after start-up instead of the normal three seconds. Two weeks ago I tried re-torqueing the left head (the easy side) and voila! She has been geyser free ever since. 
Just one more thing to try before a head gasket/O-ring replacement.
Vince
85' Westy

Date:    Tue, 10 Dec 2002 05:10:20 -0800
From:    Brian Spisak <bspisak@HOTMAIL.COM>
Subject: Re: Overheating Issues

> If, indeed, the O-ring seals in the cylinders are shot, why is my engine
> performance so good?  Quite frankly, when I have my van out on the
> interstates, it wants to go faster than is prudent even here in Georgia.

It doesn't take much of a leak to pressurize your cooling system over time.
And, it only has to be from one cylinder.  YMMV?

Check the thermostat, cap, and bleed the system.  Do a pressure check.  Head
gaskets are certainly the cause of last resort, but despite what all the
die-hard wasserboxer lovers say, this engine is notorious for this problem.
:-(

Good luck,
Brian

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