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Shortpunter 10-28-2007 12:34 PM

Heater core???
Hello all
I was having an issue with lukewarm heat and flushed and filled the coolant and still nothing more than lukewarm. The thermostat seems to work as the temp guage will rise and drop when it opens. The hoses to the heater core are hot and very frim on top and just warm on the bottom so I assume that the heater core is clogged. I ordered a new one and need some advice on how to replace it. Some say I need to drain the AC and radiator first can someone with experience please respond thanks:confused:

dbwvu 10-28-2007 06:51 PM

had the same problem. I hear changing the core is a pita, however I flushed the core a few times and now It has plenty of heat. Did you flush the core or the rad?

Shortpunter 10-29-2007 06:50 AM

I added the flush bottle and some water and ran it for a few minutes the added the garden hose to the top heater line and turned it on and opened th radiator cap it spewed out a lot of brown rusty water. I didn't change the thermo-Some say that it may be the reason- I have a heater core coming but really don't want to tear that apart unless I have to. I may try another flush out.

richp 10-29-2007 07:48 AM

Be careful with the lawn hose, that core normally operates at ~18PSI, your house pressure can be like 50PSI so don't blow up the core.
Use the hose in a forward backwards motion, flush the top then move the nozzle to the bottom and reverse it, keep doing that till it stops blowing chunks of crud out.
Also drain the system, refill with water and add a bottle of the Prestone 7 hour flush and then go drive it for the time specified. That stuff does quite a job.
Better do it soon before temps go down to freezing and using water and flush causes problems. If you have never done it would also suggest replacing the thermostat and the pressure cap, get them both from the dealer.
The heater core replacement is at least a 7 hour job, the dash has to come out.
If you go that route and have A/C I would also replace the A/C's evaporator while you have it all apart. Evap failure is common on jeeps.

mud707 10-29-2007 08:56 AM

I had to change my heater core b4 and it was a pain. You will need to drain the radiator, and a/c, then disconnect those hoses and your a/c. Next you have to remove the dash and unpug your heater controls. After that you have to remove the box surronding it. Once you get the old one out you have to do evrything in reverse and make sure you put the heeter box back together exacly or your duct work flap won't work. It took me about 4 hours to do the job, and some of the screws and bolts you have to remove are a pian. I hope I never have to do it again.

Shortpunter 10-30-2007 05:30 AM

Has anyone on here tried CLR (calcium, lime rust) in the heater core. I had a buddy suggest that you can disconnect the hoses from the block and add this then flush and it works great- I don't know that much about it other than I wouldn't want it in the block.

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