Heater Core Issues

H

Harbison

New Member
Joined
Dec 1, 2022
Messages
2
Location
Texas
Just bought 2009 Wrangler JK X, 90K miles. Heat at vents from left to right: 80, 120, 140, 160 on 40 degree day (Fahrenheit).
Both heater hoses measure the same, nice and hot.
Here are the steps taken so far.
1. Verified blend door under steering wheel next to center console is functioning properly.
2. Flushed heater core with 20 gallons of water going both directions through heater hoses, refilled heater hose with antifreeze before reattaching. (no change)
3. Performed coolant system flush using Prestone Radiator flush. Ran 3-4 hours, drained and filled with water, drained again. (no change)
4. Flushed heater core with 20 gallons of water both directions through heater hoses again. (no change)
5. Filled with Mopar coolant and bled system with front wheels on ramps. Filled heater hoses with coolant. (no change)

I have seen some YouTube videos using Muriatic Acid to flush the heater core but solution only worked for about six months. Heater core was replaced and found to have greasy sludge inside. Is there a lasting solution to this problem? Thanks for your help!
 
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Have you burped the air out of the system? If not jack the front up about 6-8" take cap off and let engine idle, add coolant as the level drops.

A air pocket will cause the engine to overheat and if the air pocket is in the heater core it won't let you have any heat.
 
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Yes. Had front wheels on ramps to bleed system. Ran engine for 30 minutes with a big coolant funnel attached to the radiator to allow air bubbles to escape.
 
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You might try it again if you've driven the Jeep for a while, there was another Member about a week ago that had the same issue and it took 2 times to burp it.
 
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BLACKJKU said:
You might try it again if you've driven the Jeep for a while, there was another Member about a week ago that had the same issue and it took 2 times to burp it.
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I need to try burping my system too. I have a similar issue as well. I've flushed it back and forth like the OP but it still exist. But its now -10F. So I'm not going outside to deal with it. It gets pretty cold on the drivers side.
 
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The various temps at different locations suggest that the problem is NOT the core getting up to temp. Inlet and outlet hoses indicate full temp to the core also.
 
terdogjk said:
The various temps at different locations suggest that the problem is NOT the core getting up to temp. Inlet and outlet hoses indicate full temp to the core also.
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I don't think that is accurate. Different temps on different vents has been shown to be the JK heater core. I had the same issue with differernt temps between driver and passenger side and flushing the heater core last fall helped. At least for 1 winter. Now its back again and the 2nd flush has been less effective. I don't know how the heater core is designed, but my understanding is the drivers side sits on the lower half of the core and it can fill with sludge or sand or some unknown substance. It seems to be a common problem with no 'cure all' solutions.
 
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