I'd crack the bleeder on the radiator when it was hot and see if air
hisses out or just coolant. If it was air I'd look for the leak.

Rob
becida@comcast.net

At  10/23/2008 09:32 PM, John Bange wrote:
>In an effort to keep the Boston Bob engine in my workhorse daily
>driver alive forever as a monument to his art, I'm trying to solve
>this new potential problem in a timely manner. I'm seeing higher than
>usual temperatures at idle lately. Radiator, hoses, thermostat are
>less than 3 years old, changed with the engine. Water pump was
>installed new on the previous engine 6 months before it crapped out.
>Symptom specifics: normal temps on the road, but at idle the needle
>rises farther above LED than usual, and when the fan comes on it stays
>on much longer and the needle drops much slower than previous. Opening
>the heater valve at idle and turning on the fan brings a slightly warm
>breeze, giving it a little gas and bringing the idle up to 1800-2000
>turns the breeze to a scalding blast that feels like it could blister
>paint. I think I've pretty much narrowed it to a coolant flow issue!
>Is this a failure mode of these water pumps?
>
>--
>John Bange
>'90 Vanagon - "Lastwagen"
>'90 Vanagon GL - "Wiesel"