Problem: I am loosing coolant.
Facts:
Expansion tank replaced by PO about 2 months ago.
1) about 3 weeks ago I filled the fill up tank(behind the license plate)
to the Max level. The expansion tank was full.
2) Next day fillup tank down to min.
3) Next day fill up tank empty.
4)Expansion tank stays full for 2 weeks.
5) 2 days ago I find a big 'ol air bubble in the top of the expansion
tank.
6) I park on gravel, so drips are hard to spot. However, after 30
minutes on the highway at 65mph and the A/C on high, I park on nice
cement. (my work)
7) I spend 5 hours there, and there are zero leaks on the ground under
the van.

Theory:
I know that there are places that coolant will leak but not
perceptively. Because of my unwillingness to crawl on my back in the
gravel (I know I can put something down) I have come up with a theory
that would not require me to crawl under the car.

I propose the following:

The leak is either in the filler up tank or in the hose between said
tank and the expansion tank.
At first, all of the coolant from the fill up seeped out the leakage.
The expansion tank was not effected until it became quite hot, and it
had to send some coolant over to the fillerup tank. While this coolant
was at the fillerup tank it seeped out. The engine cooled down and
wanted to suck the extra coolant back into the expansion tank, but since
it was not there it had to take what was there, AIR.
BTW, the hose between the 2 tanks appears to a cloth covered hose
similar to those used by AC VW for fuel lines. Is this normal?

How could I test this theory? I need to "make" coolant got from one tank
to the other while I can watch it.

Is this a reasonable theory, or am I looking for fruit on an empty tree?

Thanks....

--
Chip Shaner
4 kids and 1 cookin'.......
http://www.fament.com/chip/vw/vw.html  - The Un-named VW page