I bought a 2001 ram 1500 5.9 a couple of months ago. I’ve put

a new thermostat in it. Truck runs cold between 110 and 210. I live in Alabama so it isn’t really cold right now. During the summer it would stay the same unless it was close to 100 degrees out and I let it sit there and idle. Maybe once or twice it got close to 210. Any help please?

 

Check it with a temp gun to see if the gauge reads correctly. If it is, your thermostat isn't closing all the way.. I have good results with Gates from Rock Auto. I like to drill a 1/16 or 1/8" hole in the flange so air can't get trapped.,

 

Gauge is reading perfectly. Should never get to 210. Stock stat was 195, most of us run 180.

 

I just put a heater core in it and the heat isn’t all that great. That’s what makes me think that it is actually running cold. I ordered a temp gun so ig I’ll see

 

These trucks are notorious for being difficult to get all the air out of the heater core....

 

Yes this will haven't gotten all the air out of mine and that was 2 months ago

 

Drill a small hole in the t stat! This will allow the air in the top of the intake to escape so water can flow to the core. Also what type of core did you put in oem style or the aluminum ones?

This is an LA but the Magnum is the same way.

 

I just put one in from advance so not sure. And do you think I need to drill a tiny hole in the tstat?

 

You don't need to but many say it helps. I never have and I'm on like the sixth stat already.

 

If it's from Advanced it's probably not opening at the correct temp. Get a Gates or a Stant Superstat. I personally drill a 1/16 or 1/8 inch hole in the flange to let the air bleed through.

Some of the really cheap heater cores don't have enough tubes and fins to transfer the heat from the core to the air, so you don't get really hot air for heat and defrost.