Perplexing heat issue
01-29-2017, 09:55 AM
#1
JK Enthusiast
Thread Starter
Perplexing heat issue
2008 JKU with about 205k km on it.
My son's daily driver. He reported that it was losing coolant and that the heat wasn't working. This jeep used to burn your hands it was so warm. I figured low coolant was the issue
He topped up the coolant a few times and didn't get around to having it looked at. Called the other day and he was pulled over as the temp light had come on. Had it towed and the shop pressure tested the cooling system and found a leaking rad. Replaced the rad and tstat and it now runs spot on middle of the gauge rock solid like it used to .....but the heat problem remains. Guess the issue was coincidental. It also gurgles quite a bit on startup and accelerating from the core area for a while until fully hot. He says it has done that for about a year. If you run the fan at half speed you do get warm air but it is not near what it was.
I verified that the blend door actuator linkage is working as it should and that the mixer on the glove box side is working fine.
inlet and outlet of heater core (measured behind the glovebox are within 6 degrees F of the other.
I am pretty sure its a partially blocked core and that I will have a rad shop flush it. Only other thing could be air in it but I have run it with front way high to purge air.
Any other ideas?
My son's daily driver. He reported that it was losing coolant and that the heat wasn't working. This jeep used to burn your hands it was so warm. I figured low coolant was the issue
He topped up the coolant a few times and didn't get around to having it looked at. Called the other day and he was pulled over as the temp light had come on. Had it towed and the shop pressure tested the cooling system and found a leaking rad. Replaced the rad and tstat and it now runs spot on middle of the gauge rock solid like it used to .....but the heat problem remains. Guess the issue was coincidental. It also gurgles quite a bit on startup and accelerating from the core area for a while until fully hot. He says it has done that for about a year. If you run the fan at half speed you do get warm air but it is not near what it was.
I verified that the blend door actuator linkage is working as it should and that the mixer on the glove box side is working fine.
inlet and outlet of heater core (measured behind the glovebox are within 6 degrees F of the other.
I am pretty sure its a partially blocked core and that I will have a rad shop flush it. Only other thing could be air in it but I have run it with front way high to purge air.
Any other ideas?
01-29-2017, 11:17 AM
#2
JK Super Freak
Join Date: Apr 2008
Location: Thunder Bay, Ontario
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Sounds like an airlock in the heater core. Have him crank the heat on full to help it circulate and let it run till the engine is hot. Or take it on a long highway run.
The other way is to, again, crank the heat up inside to full, run the engine with the rad cap off and watch for air bubbles.. once the engine is hot the thermostat will open up and should flush any air out.
The other way is to, again, crank the heat up inside to full, run the engine with the rad cap off and watch for air bubbles.. once the engine is hot the thermostat will open up and should flush any air out.
01-29-2017, 02:24 PM
#4
JK Enthusiast
Thread Starter
Sounds like an airlock in the heater core. Have him crank the heat on full to help it circulate and let it run till the engine is hot. Or take it on a long highway run.
The other way is to, again, crank the heat up inside to full, run the engine with the rad cap off and watch for air bubbles.. once the engine is hot the thermostat will open up and should flush any air out.
The other way is to, again, crank the heat up inside to full, run the engine with the rad cap off and watch for air bubbles.. once the engine is hot the thermostat will open up and should flush any air out.
01-29-2017, 03:46 PM
#5
JK Super Freak
Join Date: Apr 2008
Location: Thunder Bay, Ontario
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In some applications there is a heater line control valve which restricts the coolant flow to the heater core to keep heat out of the cab. Not knowing whether or not a vehicle has said valve, this is just a common sense step in purging air from the heater core.
If this is not the case with the JK then I stand corrected.
If this is not the case with the JK then I stand corrected.
