You say your pump was replaced. Serpentine belt pumps spin in reverse rotation. "smooth pump pulley" If a older pump was put on it could also cause your problems. As far as I know, you can only tell the difference with the pump off, looking at the impeller. The outside looks the same.
To add to the confusion I have a 86 LTD motor in my Bronco. It came with a serp belt but does not reverse spin. "The pulley is grooved" I know the pumps changed somewhere in those years.
The other sugestions are also good.
__________________
Frank
|