Winter time is here and I notice my heater isnt blowing hot air at all. I will take about an hour before it starts blowing even warm air. During summer I did a full radiator flush, changed the water pump, fan clutch and thermostat. I know people suggest the heater core a lot, what should I be checking to determine if that is the issue or not?

 

Do you have a temperature gauge? What's it showing during this hour?

 

I used to have a MAJOR heating problem (thus the radiator overhaul) and after changing all that, it runs a lot cooler, usually around 160.

 

What temp thermostat you using?

 

160?? That is not normal. 195 is proper thermostat temps with around 210 being normal

 

Only gets that way after a lot of running. The new fan clutch and pump are pretty powerful and like I said dropped temp huge.

 

Jeeps optimal running temp is 210 and running less means you put undue stress on your motor.

 

I'd get some actual temp data. Your dash gauge may be right. But it might not be too.

Get a point and shoot infrared thermometer (inexpensive under $20 and widely available) and point it directly at the thermostat housing of a hot engine. What is that temp?

Also get temp data from both hoses, inlet and outlet of your heater core.

Cab heat is directly related to coolant temperature. Once you start snooping around, you will likely find the primary culprit.

Is your radiator cap new(er)? Often ignored, very important.

But yes, that heater core might be in play here.

 

I would put money on your thermostat being faulty and stuck open. You can have the world's most powerful fan clutch and waterpump and it shouldn't make a bit of difference how long it takes to get up to temperature. If your thermostat is doing its job, it's closed until the engine reaches the temperature it's rated for. Until then, neither of those things matter.

Do yourself a favor and replace whatever thermostat you put in there with a proper Mopar 195 degree stat.

 

Possibly plugged up heater core. Or it could be faulty. Try flushing the heater core in the reverse direction the flow goes.

 

Change out the thermostat first. If no dice, my guess is heater core.

 

Can I do the test of running my heater and feeling the two hoses? I was NOT running it and the top felt hot and the bottom only felt warm.

 

Also, when I overhauled the cooling system I put a new thermostat in, as well as a new radiator cap.

 

I changed my thermostat 4 times (!) until I got a properly working one!

 

If reading this forum for the last 10 years has taught me anything, it is that your experience is the norm rather than the exception.

This is what everyone says, and if you don't believe me search the forum. Get a 195 degree Mopar, and you'll have a better chance of getting one that actually works.