When I changed my radiator out, I had a big air bubble in the system
that pushed coolant back out the tanks.

To bleed completely, I alternated between putting the van on an uphill
and downhill and removing the bleeder screen until coolant came out.
Took a few times to get it happy.  You might try this as it's easy to do
and maybe find more air in the system.

Don Hanson wrote:
>   My first 'longer' trip in my 84 (with an inline 4 Golf Jetta motor) since
> around Xmas.  I've been driving it, after letting it stand for a few months,
> for a month now on shorter trips.  Everything seems fine, no poor running or
> power loss, no strange behavior at all...
>
>  I may be 'gunshy' now or perhaps overly-concerned for no real reason but
> when I first got this van, I caused myself some extra work because I was
> unfamiliar with the WBX cooling system. I  didn't get a proper air-bleed
> after flushing the coolant for new..This resulted in some odd temperature
> behavior issues that I didn't 'pick up' on until I had damaged my
> headgasket.  I had to replace the headgasket on the I-4 motor, no big
> deal..about 3-4hrs only, but I could have done BIG harm if I'd ignored
> it...thanks to the list I caught it in time to avoid major damage..So now
> I've learned to pay close attention to how my WBX cooling system (the I-4
> plugs almost directly into the stock vanagon 'circulatory system') is
> behaving.
>
>   Yesterday I did about 250 miles around Mt Hood going to and from a bike
> race and I noticed my temperature gauge was reading slightly lower than
> usual.  I put a tank of premium fuel into the van and that is what I was
> burning on this trip, if that would make a difference.
>
>   My temp gauge usually reads on or just slightly above the second of the
> bottom two marks...below that  LED.  Yesterday I was seeing the needle just
> above the bottom of those two lines, even when climbing to ~5000'...until I
> got back to low elevation when I noticed it back nearly to where it always
> has been...Some fluctuations in the reading...Not a fluttering of the
> needle, the gauge looks to be operating normally...but the needle would
> move, over a 10-20min period from quite cool to where it normally has run
> and maybe fall again...So my gauge is showing 'system running very slightly
> cooler than normal'
>
>   When I got home I went back and opened the license plate to check my
> coolant overflow tank level.  It was over-full and poured out about a cup of
> coolant when I removed the cap...So I opened her up to check the pressure
> tank...No air in there.  The coolant looks normal, also..no combustion by
> products are evident.  Water pump feels fine, though I didn't take off the
> drive belt and spin it...Next, I went to the air bleed screw in the rad.  It
> took about a cup of coolant, added right into the bleed screw hole, as I've
> devised as 'my' method of getting the last air bubble out of my radiator.
>
>   So what would cause my coolant to 'migrate' from the pressurized cooling
> system into that overflow tank? and should I be concerned?  It's not
> running  out of the Normal temp range, but pretty close to 'too cool'... any
> change in operating temp is alarming to me, since when my first problem
> happened, the symptoms were 'cold air from the heater' and the temp gauge
> behaving quite erratically...
>
>   Don Hanson
>
>
>