>From: dbax@mindspring.com (Donald Baxter)

> It also turns out that the van was, in fact, overheating at traffic lights
> while remaining perfectly cool at freeway speeds.  The needle goes up to hot
> very quickly in traffic.  Incidently, no leaks detected anywhere except from
> the overfilling fill tank at the top vent holes--nothing from the water
> pump, heads or at the front of the van.

My father had this problem recently with our 85.  It would boil over into
the overflow tank after a high speed run or sitting in traffic.  He thought
it was the thermostat being stuck or the radiator fan switch broken.
The temp guage would only be about half way when it would happen.  I checked
out the fan switch by letting it run until it came on  with out any problem.
The gauge would be 3/4 by the time the fan came on.  That was normal.

I then suggested getting a new expansion cap.  The one we had was the
original one.  He got a new one from the vw dealer.  Overheating/boiling 
was solved.  It seems that the old cap had lost it holding capacity.
It has not overheated since then.

Jonathan
jdove@gsvms2.cc.gasou.edu