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post #1 of 16 Old 03-12-2019, 07:26 PM Thread Starter
yj-jachal
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No heat

The heat in my 90’ yj does not get very warm.. I’ve changed thermostat , new coolant to no avail.. was thinking heater core might be plugged... any thoughts?

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post #2 of 16 Old 03-12-2019, 07:55 PM
Boojo35
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Yes. It could be the cause. How hot do the radiator hoses get? Too hot to touch? What is coolant temp on gauge? If hot enough then it maybe a plugged heater core. Feel or touch you heater hoses where they go into the firewall. Is one almost to hot to touch or hold onto for a couple of seconds and the other one is luke warm or cold? If that is the case. The heater core is likely plugged.
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If you cannot fix it with a hammer then it has to be an electrical problem.
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post #3 of 16 Old 03-13-2019, 04:38 AM
CESWAMPY
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When you replace your heater core. Do blower motor upgrade if that is not already done. You will like the outcome!!!!
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post #4 of 16 Old 03-13-2019, 05:15 AM
fishadventure
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Originally Posted by CESWAMPY View Post
When you replace your heater core. Do blower motor upgrade if that is not already done. You will like the outcome!!!!
Agreed. One of the best things I did. And I live in the deep-freeze belt

[size=“3”]Shackles & D-rings are different things.
Cranking IS turning over
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post #5 of 16 Old 03-14-2019, 10:44 AM
bharris68
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I have been trying to find a thread where the process for enlarging that hole PROPERLY is detailed with pictures.. I can find the threads, but most of the pictures are no longer showing


The two prescribed methods are:


1. pop rivet or otherwise secure a fresh plate of thin material over the existing hole so your new hole-drill pilot shank can have something to dig into and cut all the way around cleanly.


2. create a wood template the SAME diameter as the existing hole. it should be thick enough that it will sit inside the LARGER diameter hole saw. In this way - the pilot shank has the wood block firmly inside the existing hole and the hole saw can cut a nice, clean hole for your new blower motor.


I did not follow either of the two steps above.


I did GET the hole "enlarged"... but it looks like a 9-year-old did it with scissors and a file.... I would spare you that embarrassment .


When I have to drop the heater box again, I'll make it nicer for sure. At the original point in time, I had to get it back on the road because it was my daily driver
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post #6 of 16 Old 03-14-2019, 01:03 PM
CESWAMPY
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I used #2 method. Then if you go to quadratec and type in heaterblower to firewall seal it should show the right seal needed for the larger motor. You need the one that is completely round!!
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post #7 of 16 Old 03-14-2019, 07:58 PM
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Originally Posted by bharris68 View Post
I have been trying to find a thread where the process for enlarging that hole PROPERLY is detailed with pictures.. I can find the threads, but most of the pictures are no longer showing
The last one I did, I drew I line in perm marker about 1/4” from oem opening. Then I took the 1/4” die grinder and slotted the opening’s perimeter. I hammered it over to the inside.
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[size=“3”]Shackles & D-rings are different things.
Cranking IS turning over
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post #8 of 16 Old 03-15-2019, 10:25 AM
JMAC90YJ
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I used existing holes and bolted a piece of treated lumber to it and then drilled out the hole.
Attached Images
   
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SOME PEOPLE ARE LIKE SLINKIES - NOT REALLY GOOD FOR ANYTHING BUT THEY BRING A SMILE TO YOUR FACE WHEN THEY'RE PUSHED DOWN THE STAIRS.
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post #9 of 16 Old 03-15-2019, 10:28 AM
bharris68
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Thanks JMac! That's one of the picture sets I was hoping to find
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post #10 of 16 Old 03-17-2019, 04:48 PM
zrickety
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A new heater core goes a long way. I also did the fan upgrade, O'Reilly had it in stock! I enlarged the hole using a cut off wheel and bending the metal back. In retrospect, I should have just used tin snips. Home depot has some great weather seal you can wrap around the motor, something like 3/4"? You'll know once the old one is out. My heater almost blows fire now.

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post #11 of 16 Old 03-17-2019, 08:38 PM
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Have you tried back flushing the core? I was getting very little heat on my 88 and did a backflush of the core. Disconnect the two heater hoses. One at the water pump and the other behind the carb on the intake manifold. Run water thru the hose from the water pump (return line) thru to the hose heading to the manifold. A big slug of green snot and some grit came out of mine. Then reversed the flow a couple of times back and forth. After that, my heater was hot again. Worth a try before you go thru all the trouble of replacing the core.

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post #12 of 16 Old 03-17-2019, 09:25 PM
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His 1990 would likely benefit from a new blower motor though, and if you’re that far you might as well spend $22 or whatever and get the new motor in at the same time.

[size=“3”]Shackles & D-rings are different things.
Cranking IS turning over
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post #13 of 16 Old 03-18-2019, 10:13 AM
defmornahan
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Quote:
Originally Posted by Rudys88 View Post
Have you tried back flushing the core? I was getting very little heat on my 88 and did a backflush of the core. Disconnect the two heater hoses. One at the water pump and the other behind the carb on the intake manifold. Run water thru the hose from the water pump (return line) thru to the hose heading to the manifold. A big slug of green snot and some grit came out of mine. Then reversed the flow a couple of times back and forth. After that, my heater was hot again. Worth a try before you go thru all the trouble of replacing the core.
I think it's worth trying to flush the heater core and also cleaning up the contact for the blower motor and maybe replacing the connector with a new female spade terminal while you're at it. My blower works noticeably better for that.

If that doesn't work, then yeah, you need to dismember the dashboard and replace the core, and you might want to replace the fan. A real pain in the *** if you have that awful bolt-on air conditioning evaporator in the way. I took the opportunity to remove the one on my '87 completely (I doubt it had been working since the 20th century).


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post #14 of 16 Old 03-19-2019, 08:15 PM
Mechman71
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IMO your old heater core is worth saving and repairing. My 89's stock core is made of brass and fits perfectly in the box, all of the brackets line up. The replacement was aluminum and smaller so I would have had to wrap it around the edges with foam to make it wedge in. I took my core to a radiator shop where they flushed and tested it. My problem wound up being a bad hose, so I returned the new core and have been warm and happy ever since.
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post #15 of 16 Old Yesterday, 04:03 PM
Matthewavogt
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Is your engine hitting temp?
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