I got my 86 out from winter dulldrums and drove 200 mile trip.  Noticed
that reserve overflow was filled and the tank itself was low.  I drained
some from overflow (when engine was sitting overnight) and then proceeded
to open the main coolant tank to put in more fluid.  As soon as I loosened
the blue cap pressure started filling it up from the rest of the water
system.  I quickly tightened it down.  When I run it - it gets low again.
 I have never had this problem of pressure being so great that I can't just
simply take main tank cap off.  Could this be a bad cap?  It is a newer one
which I got because it looked newer.   Can't seem to find the old one.
 Ideas?

Kurt Grotz
484-477-2109
kurtgrotz@gmail.com
86 Vanagon (Rexmobile)
87 Westy (Sky)