i just replaced my waterpump on my '93 f350 as the old was was leaking through the lower weep hole and whining.
But the new one wants to run hot and fluxuate as i drive now. I cant seem to find anymore air in the system.

The water pump is a new cardone one. and i couldnt find any leaks anywhere.

I checked and when it is hot, the clutch fan moves freely, and is stiff when its cold.

Could air still be in the system somewhere?

 

Did you by chance change the thermostat at the same time you did the water pump? (I'm thinking possible bad new thermostat) Does your heater work good now?

 

X-2 thermostat ....Lew

 

thermostat is also new. And the heat worked great before and now. but before, it would get could sometimes as it was leaking fluid.

 

I went out last week to crank truck up and warm it up. Went down the road and temp climbed to almost H. Got back to the house and tapped on T stat housing to get T stat un stuck. (Had no problem before with it.) Was on the verge of changing it out and decided to take off top house and pour antifreeze in it. T stat opened up, topped of radiator and have not had any more touble.

 

OK then I would definitely say your new thermostat is defective. The fact that your heater is working good tells me there is no air in the system.

 

There is another possibility. If the fan isn't pulling the air through the radiator properly, that would cause overheating and fluctuating temperatures in city driving. On the open highway at say 50 MPH or more you wouldn't need the fan, the motion of the truck would push the air through the radiator.