I'm having the same problem, I think exhaust gases are getting in the
cooling system in mine. You need to take your vehicle to a radiator repair
shop or a mechanic, and have them test your cooling system for exhaust
gases. They use a chemical that changes color if there's a problem. Good
luck.

Hector
1990 Carat 'Ursula'

On Fri, May 25, 2012 at 1:24 PM, Richard Golen <rgolen@hotmail.com> wrote:

> I think my pressure cap on my 87 is dead. Here are the symptoms.  Temp
> gauge is in middle. But coolant overflow tank fills up and overflows after
> 2hrs of highway driving.   When the van sits overnight the overflow tank
> still is full.
>
> Is the cap?
>
> Ric
>
> Sent from my iPhone
>