Over heating at high speeds
 

Hello folks
My 1987 F-150 4.9 over heats at 70mph,or when my a
A.C. is running. Also when I am towing a small boat. I check out my fan clutch it is ok. The engine has been rebuilt. When I first
bought my f-150 it did not have a thermostat in it. I put a 195
degree one in but it boil over. I then went to a 165 degree
thermostat in. If the temp reaches 200 it will not stop.
The radiator is new but only has 2 row of tubes.
It also has a manuel 4 speed transmission.
Any ideas????
Bruce:confused:

Sounds like the water pump to me.