Overheating at low RPM's?

[duke]

Lately I have been having a overheating problem, but it is only when cruising at low RPM's. If I am cruising at less than 3K RPM's, no matter what the speed (freeway, back road, etc) the temp gauge goes up to around 215-220 degree's. As soon as I shift down and bring the revs up it will drop down to normal operating temp. My first thought would be water pump, but the last time I had it out (a few months ago) it looked fine. Any idea's as to what the problem could be?

[Byron510]

You didn't do an under drive pulley and go a bit too far with the ratio did you??

But it would seam like it's a circulation related issue. Have you backed up the gauge reading, or do you have both the stock gauge and aftermarket gauge agreeing something isn't right??

You don't have a blockage in the rad as well? Full of bugs, or even dirt...

Just throwing various thoughts out there, but I would suggest that the water pump may also be an issue. Seems odd though, as a water pump problem that is that bad would usually be linked to a bad bearing and likely a leak. And it’s unlikely that a loose belt could cause this as your alt would also not be working…..

Let us know what you find.

Byron