2015 JKU Overheating With No Heat

ttrein

New Member
Joined
Feb 20, 2024
Messages
7
Location
Northwest Wisconsin
I just replaced the water pump and thermostat. Refilled the radiator and started it with the funnel attached and with coolant in it.

The temp got up to about 230F before I shut it off. The top radiator hose stayed cold and there was no heat in the cabin.

Is it possible there is a big air pocket in there causing this? Originally i thought maybe the thermostat was bad, but after reading a bit it looks like I should still be getting heat from the heater core even if the thermostat is faulty.

Any suggestions on what to do before I replace the thermostat?

I replaced the water pump because it was leaking. Everything was working fine otherwise before this.

Thanks!!!

Todd
 
You need to raise the front of the Jeep up about 6-8", radiator cap off, engine idling, add coolant as it starts dropping.
 
You need to raise the front of the Jeep up about 6-8", radiator cap off, engine idling, add coolant as it starts dropping.

Just tried it with same result. I checked the heater core hoses. The one one on the passenger side is hot, the drivers side isn't. I was planning on flushing out the heater core but its -5 outside. Would a clogged heater core cause the thermostat to not open for any reason?

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Did you have your heater set to heat when you did the burp?

Heater core shouldn't have anything to do with the T-Stat.
 
Did you have your heater set to heat when you did the burp?

Heater core shouldn't have anything to do with the T-Stat.

I did have it set to heat, yes. Thanks for confirming they are unrelated. I'm going to swap thermostats once it cools down a bit. I'll battle the heater core another day... hopefully it's just a bad tstat!
 
Welp. Finally got it. There was an air bubble in the block somewhere. I cracked open the purge screw on the thermostat (while running). I dont understand how the air didn't just get pushed up through the radiator hose but it didn't. Haven't driven it anywhere yet, but the heat works now and the thermostat opens just fine.