Heat not hot - Need advice - JeepForum.com
 
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post #1 of 14 Old 01-16-2018, 02:31 PM Thread Starter
igorhandsome
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Heat not hot - Need advice

Did a coolant flush when I got my Jeep in July. I did not flush the heater core at that time..didn't know I needed to but realizing now I should have. Heat is warm not hot. Here's what I've checked:

-heater hoses both feel fairly warm
-Jeep gets up to temp normally and stays there
-no coolant leak or coolant in oil or missing coolant no white smoke etc
-heat/cold dial changes temperature so it shouldn't be blend door?
-all HVAC controls work as they should as does the fan on all speeds

I'm thinking flushing the heater core is the next step. Is it possible the coolant mix is too strong? Any other advice?

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post #2 of 14 Old 01-16-2018, 02:43 PM
jtec
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new thermostat. correct rating, 195 I think

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #3 of 14 Old 01-16-2018, 02:47 PM Thread Starter
igorhandsome
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I can try that as well
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post #4 of 14 Old 01-16-2018, 03:31 PM
PolkaPower
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Quote:
Originally Posted by igorhandsome View Post
I can try that as well
If the thermostat is stuck open you'll never get it hot.
Failsafe thermostats do this all the time. Don't ever use those.
Stant, Mishimoto, or Mopar. I think K&N makes a nice one too.
Before I install them I test them in a pot of water on the stove. Don't boil it, just warm it up until it opens and read the thermometer.
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post #5 of 14 Old 01-16-2018, 04:23 PM Thread Starter
igorhandsome
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Maybe there's air in the system? I bought one of those no spill funnels and I'll try that this evening and see if that helps at all.
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post #6 of 14 Old 01-16-2018, 10:14 PM
RedRiverT
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I would say it is likely air trapped in the heater core or one of the hoses. I got my '97 several years ago at the end of April, replaced the radiator in August, then found out a few months later I had the same issue as you, warm not hot. I read on here about the common issue of air trapped and how to fix it. I tried driving up on an incline and revving it, parking sideways on an incline, etc. I finally took both hoses off at the front and held them up, filled them both, then held one in each hand and moved them up & down oppositely to move the coolant back and forth. It bubbled pretty good after a few times and I topped them off and reconnected and had firey hot heat.

EDIT: Oh yeah, some guys have installed a flushing connector in one of the heater hoses and fill through there, holding it up so it is the high point and you don't get the air bubble.

EDIT 2: Some people claim that it will flush the trapped air itself after a number of "get hot, cool off" cycles.
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post #7 of 14 Old 01-16-2018, 10:37 PM
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4.0 is a bit trickier to get all the air out of the system compared to the 5.2/5.9 magnums. 4.0 should self-bleed just like the magnums do, but I've heard it enough times and also remember both my 4.0 XJs being pretty hard to get all the air burped.

However, it's also possible your heater core is either internally or externally partially clogged - or both. When I pulled the dash/ HVAC box on my niner, and replaced both the evap and heater cores, there was a big difference in the cabin heat when temps got down to single digits or negatives.

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post #8 of 14 Old 01-17-2018, 10:36 AM Thread Starter
igorhandsome
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I'm pretty confident now the heater core just needs to be flushed. Since it's supposed to be quite a warm week here I will get the heater core all flushed out and see how it is.
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post #9 of 14 Old 01-17-2018, 12:53 PM
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I think if I had of flushed mine more than I did, it would have worked and I wouldn't have needed to change the core. I don't know. Work it back and forth like 25 times not just until you get clear water. I did that and it didn't clear my clog.

Both hoses hot, new thermostat, no air trapped.. still ****ty heat. What solved it? A new heater core.

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post #10 of 14 Old 01-24-2018, 11:20 AM Thread Starter
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Thermostat has been replaced and the heater core flushed. It's maybe a little warmer now but still not where I think it should be. I read elsewhere someone suggested using CLR on the heater core. What do we think of that idea?
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post #11 of 14 Old 01-24-2018, 11:32 AM
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Quote:
Originally Posted by igorhandsome View Post
Thermostat has been replaced and the heater core flushed. It's maybe a little warmer now but still not where I think it should be. I read elsewhere someone suggested using CLR on the heater core. What do we think of that idea?
https://youtu.be/dcL_0TWeZJY
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post #12 of 14 Old 01-24-2018, 12:26 PM
RWC
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I tried CLR and it didn't do me any good. I think a PO had clogged the core with BarsLeak or a similar product. Coolant went through it, but no matter what I tried (FlowKooler pump, EMP/Stewart thermostat, flushing, flushing with CLR, burping with the correct tool, etc.), the air was lukewarm at best. I finally threw in the towel and replaced the heater core. Problem solved.
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post #13 of 14 Old 01-24-2018, 03:10 PM Thread Starter
igorhandsome
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I don't like the compressed air idea...isn't that too much pressure?
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post #14 of 14 Old 01-25-2018, 04:02 PM
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https://youtu.be/KhEd49-XPvU

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