I was taking my '88 Westfalia down the freeway when, after having to reduce
spped suddenly due to traffic (from about 75mph), The red water temp light
started flashing. Then, as I was pulling over, the temp gauge started
rising.

When I stopped I noticed that the back window was sprinkled with coolant and
the licence plate looked like someone had hit it with a water balloon. In
looking at the engine compartment, the expansion tank was very low, but the
overflow tank (behind the license plate) was full past the top of the fill
cap.

I filled up the expansion tank and drove on everything now reading normal.
About 60 miles later the coolant light started flashing - but the temp
showed normal. I stopped and filled the expansion tank again, and this time
let the extra coolant drain out of the overflow tank.

I had to stop one more time and add coolant to the overflow tank, but then
was able to travel 200 miles with no insident after this.

I originally thought that there might be a leak in one of the tanks or a
hose somewhere - but I do not understand why it seems to have fixed itself.
Could it be that I just had a huge air bubble in the system?

Anyone have ideas?

Thanks
Todd
'88 Westy