Poor Heat: what am I missing? - JeepForum.com

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post #1 of 18 Old 12-17-2009, 04:14 PM Thread Starter
richla
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Poor Heat: what am I missing?

Here is the deal: ten degrees back here on the MA/NH line, but I was cold on the way home.

In the last month, I have flushed the cooling system almost to death (installed back flushing tee, etc).

Replaced a faulty radiator cap.

Flushed the heater core on it's own, backwards, forwards, etc.

After each step (above) I seem to have nice heat, and then it slowly declines again.

Blower seems fine, I can easily switch to defrost, just blowing on my feet, etc. Good airflow, but "barely warm", not hot.

I do notice my top heater core hose gets real hot.
My bottom hose is significantly cooler. I think THAT is the problem, I need to flush the core again.

I have plenty of engine heat, gauge sits at 210 degrees, coolant looks real clean, and when I flushed that core, I could easily blow air/water in and out, but I keep going back to that core as the potential problem.

Any thoughts or suggestions, besides "get a heavier coat?


To make this worse, I drive a guy home that thinks Jeeps are junk, and tonight's ride home didn't help!
Thanks!

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post #2 of 18 Old 12-17-2009, 05:11 PM
DeconsTructionJ
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Quote:
Originally Posted by richla View Post

To make this worse, I drive a guy home that thinks Jeeps are junk, and tonight's ride home didn't help!
Thanks!
did you replace the thermostat? it may not be opening and closing properly..

it sounds like your heatercore may be plugged still or need to be replaced.

as for the guy that thinks jeeps are junk.... where is his vehicle? I cant stand people that complain about things and dont have anything better to compare it too

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post #3 of 18 Old 12-17-2009, 05:13 PM
machone169
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sounds like you got a stuck or faulty theromstat
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post #4 of 18 Old 12-17-2009, 05:20 PM
Knuckelhead
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Quote:
Originally Posted by richla View Post
I have plenty of engine heat, gauge sits at 210 degrees!
Quote:
Originally Posted by DeconsTructionJ View Post
did you replace the thermostat? it may not be opening and closing properly..
Quote:
Originally Posted by machone169 View Post
sounds like you got a stuck or faulty theromstat
Sounds like the theromstat is working well...
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post #5 of 18 Old 12-17-2009, 05:28 PM
DeconsTructionJ
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the reason I suggested that is because my friend and I were having heating problems on his 07 superduty. The coolant temp was staying steady (according to his guage in the dash) but the heat the truck was throwing was off and on from hot to really cold in a matter of seconds.

It left us with 2 possible problems the dreaded and common blown 6.0L head gasket or a faulty thermostat.

going with the cheaper and easier diagnosis we tried the thermostat and the heat coming from the vents in that truck is borderline uncomfortable now.

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post #6 of 18 Old 12-17-2009, 06:04 PM
slowsi
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if the temps are diffrent on the inlet and outlet sides of the heater core then theres a very good chance you may need to chance out your heater core if backflushing wont move the sledge build up
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post #7 of 18 Old 12-17-2009, 06:35 PM Thread Starter
richla
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I'm ruling out the thermostat for now, as it warms up perfectly, stays stable, etc. Radiator hoses are hot and full of pressure.

I keep going back to that lower core hose being a lot cooler. Every day I'm pulling into work, opening the hood and groping all the hoses, the heat is there, but it's strange, as when I flushed the core, it seemed pretty clean and I could easily blow air and water through it, but that cold hose has got "problem" written all over it.

zero to ten degrees predicted in the a.m., this should be great...

Thanks for the input, as always.
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post #8 of 18 Old 12-17-2009, 07:03 PM
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It could be a faulty Blend Door Actuator. Read this: http://www.jeepforum.com/forum/f9/ho...repair-464741/

My favorite shops in the Northwest:

http://www.clavicle3.com

http://www.jeepwest.com
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post #9 of 18 Old 12-17-2009, 07:49 PM Thread Starter
richla
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I just ran out with a flashlight to look at the blend door.
I don't see that assembly in the pictures, but I do have a cable activated assembly that rotates left and right as I slide the temp control lever back and forth.
IF all is connected and moving o.k., do you think I can rule out the blend door?
(I'm thinking it's a mechanical assembly on a '97, in comparison to a fancier unit on a newer model?)
I'm learning way more than I need to know about a TJ's heat!
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post #10 of 18 Old 12-17-2009, 08:40 PM
narleycarley
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It's heater core dude

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2010 Dodge Durango Citadel 5.7 traded Jeep for this =(
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post #11 of 18 Old 01-06-2010, 08:15 AM
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Resurrecting this thread, OP did you ever find out what it was? Mine is doing the same thing but When i get on the throttle the heat starts coming out hot but when I lay back off it will go to cold sometimes.
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post #12 of 18 Old 01-06-2010, 08:25 AM Thread Starter
richla
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It's still the "Question of the Day" !

I have removed the heater core hoses twice since I did that post, and flushed that core to death. water and air freely passes in and out of the core.

I never had a lot of "junk" in that core, as very little debris, etc, came out of it.

I will say that the second flush (which was really the third flush on the core itself) did seem to restore some decent heat.

My thermostat and water pump all seem to be working just fine.

I have a theory that the core might have some scale built up that I just can't remove with a garden hose, and I'm not going to dismantle the thing to get at it. it's just not worth it.

I'm warm enough now, but I kind of envy the "blast furnace heat" that some guys report.

Wish I could give you a direct answer, but flushing the core seems to help.
Getting those hoses off was almost impossible, just slice off with a sharp knife and flushing is an easy job.

Good luck, stay warm
Rich
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post #13 of 18 Old 01-06-2010, 08:41 AM
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Quote:
Originally Posted by JerseyDubbin View Post
Resurrecting this thread, OP did you ever find out what it was? Mine is doing the same thing but When i get on the throttle the heat starts coming out hot but when I lay back off it will go to cold sometimes.
Did you check the coolant?

Sounds like your coolant is low.
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post #14 of 18 Old 01-06-2010, 08:47 AM
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Sounds like you need a new heater core. Some of those small tubes get plugged up and you can't flush them all out. The water moves through a few of the passages, but not enough for good heat exchange with the air. You just have to break down and do it!

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post #15 of 18 Old 01-06-2010, 08:48 AM
COMTB
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Quote:
Originally Posted by Wheelin98TJ View Post
Did you check the coolant?

Sounds like your coolant is low.
I will check again today but I just had a new rad put in, with full coolant flush obviously, last week.
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