Coolant issues

99redtj · May 12, 2014

Replace my radiator under warranty,after filling it back up I started the jeep and with 5 to 10 minutes it started to hit the red line.
I shut it off and coolant stared leaking past the lower hose at the radiator,the strange think was the coolant was cold,the lower plastic part of the radiator was cold and every think else was hot.

Not really sure why that happen. Could it be that my water pump just went out.
The fan was turning

The new radiator is not plugged.ran water through the upper hose mount on the water pump and there was water coming out the lower hose mount.

Not sure what really happen

zukkev · May 12, 2014

Thermostat, or Water pump impeller came loose on the shaft...Could also be air in the system needing bled out...

skinny_pedal · May 12, 2014

Did you have heat out the vent? If yes your pump is working. No heat no flow. I'm assuming this is on the Tj with the 4.0? If so, pull the coolant temp sensor in the thermostat housing. When your filling the radiator get coolant to come out of there. That will take care of air in the system.

99redtj · May 12, 2014

Air in the system would make sence.i filled the radiator and the I did something that I normal don't do.I put the radiator cap on and started it. I normal leave the cap off for a couple minutes after I start the engine.

KarlVP · May 12, 2014

skinny_pedal said:
Did you have heat out the vent? If yes your pump is working. No heat no flow. I'm assuming this is on the Tj with the 4.0? If so, pull the coolant temp sensor in the thermostat housing. When your filling the radiator get coolant to come out of there. That will take care of air in the system.

This. :awesomework:

WA-Wheeler · May 12, 2014

Anytime I open a cooling system I throw a new thermostat in. There cheap and easy to do plus they don't like to be dry. But 4.0 are shitty to bleed. I put a high side vent on the heater core lines to help.

Avanteone · May 12, 2014

Sounds like air. When filling a 4.0, we typically pull the small heater hose off the t-stat housing, fill radiator until coolant comes out, and put the heater hose back on. Then start and warm up like normal.