Folks,

I am working on this 90 van.  At first when i got it, the needle ran about 3/4 of the way on the gauge, and the level indicator would blink...........it seemed the coolant was low.............

First thing i did was test for exhaust gasses in the coolant using a Snap On tool i have.  None present.  Previous owner had had the system pressure tested, and said no leaks.  I replaced radiator, lower temp thermoswitch for fan, ballast resitor for fan, and lower temp thermostat, new pressure cap.  Needle still ran 3/4..............checked temperatures with infra red tool, and seemed lower than that.  So swapped sender for the gauge, and now it runs right at the red dot as most vanagons do.......traffic and long stops make the needle creep up, but it always comes right back down once you get rolling.

But there still is a wierd problem.  It seems that the pressure cap allows coolant to leave the system into the overflow, but it does not suck it back in.  So, if you have the overflow filled to max, after a drive you look at the overflow and it is 1 1/2 " higher than high, and the regular expansion tank ( the one with the fitted pressure cap) has a good sized air bubble in it.  I have bled the system more than once, and this same thing keeps occuring.  Tested again for exhaust gasses, none present, and no coolant leaks on this vehicle.   

Any ideas?

Adam P

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