Ya'll,   three weeks ago I performed my annual coolant maintenance on my '86
GL (180K miles).  I emptied the usual 7+ of the total 18+ quarts and
refilled with Autobahn coolant/water.  I have done this many times but this
time a problem.   Everything seemed fine for several days of city driving
but when I got out on the freeway ...at speed...  coolant began to get
pushed into the expansion bottle.  Once in the expansion bottle it does not
get pulled back in as would be normally expected with the expansion cycle.
If I go too far the expansion tank will overflow.  I have bled the system
twice and still the same problem.   Also of note, the van is running hotter
than usual.  I know... all indications are that there is still air present,
but I have never had this problem in the past.  Also,  I don't believe there
is any leakage into or pressure from the cylinders, etc. as all other
operations, fluids, and emissions are normal.

Does this make sense?  Any thoughts?

Eric Small
'86GL    180Kmiles