Hi all, I just installed a new water pump and thermostat on my truck, and now hardly any heat? I let the truck run for almost an hour without the radiator cap on. And I added coolant back up to the full level. I took it for an almost 100 mile ride and the temp level hardley even moved off of cold? And it is hardley even blowing warm air with the heater on hi. Any ideas?

 

What thermostat did you install? All the air should have bled out by now. It sounds like the thermostat is incorrect.

 

I tested the thermostat as soon as I got it home. Only thing is, I didn't see an arrow as to which way to install it? Could that be the problem?

 

Or could it possibly be my radiator cap? I did notice my coolant level went down a lil bit, when I went to fill it back up.......after it had been running a long time........and there wasn't any pressure when I unscrewed the cap

 

A lack of pressure will not keep it from heating up. The purpose of the pressure is to lower the boiling point of the coolant and allow leaks to be found easier.
Where did you buy the thermostat? What brand? Was the stem facing down into the water pump housing when installed?

 

I bought the stat at napa. And yes, I installed it correctly. But I did not see an arow on it? As to what way to set it in??

 

Isn't there a bypass or a pin hole of some sort to let air through if/when the thermostat is closed? Do you have an infra red thermostat that you can use to shoot temps at different locations?

 

Thanks for all the input, turns out that thermostat was junk! It wouldn't shut completely.......so had to drive an hour 1 way to get to an auto value that was open today. Gotta love small towns!

 

It definitely pays to check the stats thoroughly before installing them. my son just went through a head gasket job on his '07 Outback, then his radiator blew, and he changed the stat again "just because" -- a Beck-Arnley, supposedly a reliable brand -- and when he pulled it out after having repeated overheat issue, he found that it didn't open until about 186°F instead of the advertised OEM setpoint of 170°F. THEN he has also now learned that the opening diameter on the B-A is slightly smaller than OEM and it's open travel position is 2mm less than the OEM units.