Very little heat from new heater core

Brent o

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Jul 18, 2018
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Minnesota
I installed a new heater core this weekend from Oriely auto parts. Murray was the brand name.. and now I have very little heat output, I’ve checked the blend door and all the Diaphragms and everything works as it should, I have hot coolant going in one side and slightly cooler coolant coming out which tells me it’s working
But it’s just warm air coming out the vents not nearly as hot as it was with the old core. And if I turn the fan on high it seems to get colder like it’s cooling the core down,
Has anyone else experienced this ?
Is there a better heater core to use that puts out more heat?
It gets cold here in Minnesota!
 
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Brent o

Brent o

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Jul 18, 2018
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Minnesota
Well you are in Minnesota.
I bought my kid an electric one from amazon just to help out.
The old heater core put out so much heat I couldn’t hold my hand in front of it for very long,, now it’s just Luke warm. And we are having a warm spell (upper 20’s-30 degrees!)
 

MountaineerTom

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Did you drain coolant before changing it? Or pinch the heater hoses off and then disconnected them?

If you drained the coolant you may have an air pocket in there which would require more burping then system.

Both hoses on mine are pretty hot when the engine is up to temp. Hopefully your new core isn’t clogged up.

You could pinch off the hoses and disconnect them then run a hose into each pipe and make sure it flows out of the other one good. I wouldn’t use a nozzle on the hose that way the high pressure coming out doesn’t damage the inside of your core. Just use the hose end with no nozzle attached.
 
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Brent o

Brent o

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Minnesota
Did you drain coolant before changing it? Or pinch the heater hoses off and then disconnected them?

If you drained the coolant you may have an air pocket in there which would require more burping then system.

Both hoses on mine are pretty hot when the engine is up to temp. Hopefully your new core isn’t clogged up.

You could pinch off the hoses and disconnect them then run a hose into each pipe and make sure it flows out of the other one good. I wouldn’t use a nozzle on the hose that way the high pressure coming out doesn’t damage the inside of your core. Just use the hose end with no nozzle attached.
I did pinch off the hoses when I took it apart.. and I have put about 150 miles sinceI put it back together ...

The inlet side is about 30 degrees hotter than the outlet side telling me it’s going thru and dissipating the heat as it should be...

I also ran the hose thru it just in case some packaging got stuck in there and I missed it. Made no difference...

I’m just having a hard time believing that it puts out that much less heat

thanks for the reply
 
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Brent o

Brent o

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Jul 18, 2018
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Minnesota
X2. Air in system. Must be purged properly.
I pinched off the lines when I installed it and then I pumped water through it when I was checking it to see if it was plugged... if there is a better way to get all the air out I would definitely try it....
 
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Brent o

Brent o

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Minnesota
Update....
The new heater core was bad...
When I installed it and it didn’t work I tried everything, at one point I hooked a hose up to it and ran water thru it just to make sure it wasn’t air bound...
I checked all the doors and the weworking... and drove it about 900 miles ... still no heat...
Yesterday I installed another new heater core and I have heat again!!!


the first one was a “Murray” from Oriely’s The second one was a spectra premium from rock auto...

turns out the “Murray” is a spectra with a Murray sticker on the box...
And marked up $$ of course...
See side by side picture

E80C752E-ACA8-4957-A601-04067635110C.jpeg
 
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JEEPCJTJ

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Well that's good news that you got heat again. 👍 Bad news what needed done a second time.:mad:

I wonder why the first one was bad. Maybe it was supposed to have a Murray sticker covering those others but it got stuck inside and is blocking 3/4 of the actual metal core tubes. Maybe it was a 9 yr old chinese girl that was just starting to feel Corona virus symptoms that day. We may never know.
 

Goatman

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I guess we should be bench testing these new heatercores before installing them.😱 If you can't trust a 8 yr old Chinese girl working 20 hr days, who can you trust?🤔
 

-T.

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This is not news I wanted to hear. Going through the same situation right now. I replaced heater hoses when I changed the core, but I did not drain the whole system. I have since burped the system using a spill-proof radiator funnel, and let the Jeep run a long time. Still not very good heat this morning. Seems to get warm with some engine speed, but cools off at idle. I can't imagine there is still air left in the system. Gosh, I don't want to do that job again. Mine is a Spectra from RockAuto as well.
 

Goatman

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Are the heater hoses getting hot? It could be the core is only the symptom and not the cause. If the heater hoses aren't getting too hot to hold on to then I'd be looking to see what is preventing the hot coolant from getting to the heater in the first place.
 

-T.

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Heater hoses are getting hot. I drove the Jeep to work today so maybe that will shake loose some air bubbles. Plus, I will monitor the heater hoses more closely to see if they heat up at about the same rate - Maybe that will indicate that new core is flowing properly? I'm not sure how else to confirm that the core isn't defective. Stay tuned.
 

VallenMaes

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I just replaced mine before winter started and in order to get out all the bubbles i had jacked up the front end and had to squeeze each hose periodically for about an hour. It sucked but it worked and now i have amazing heat. I hope it helps.

Also had to replaced my thermostat at the same time.
 

-T.

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Thanks! I was just thinking that. I had the drivers side of the Jeep raised a bit to try to work bubbles toward the cap side of the radiator, but I think I will pull it up on ramps today and try again.
 

Goatman

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If the hoses are both good and hot that means fluid is moving through the core. At that point I would start looking at the way the whole heater was put back together. Something is blocking airflow through the core and into the tub. A bad blend door or missing electrical connection is a possiblity.
 

-T.

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Yes, an Update: After driving the Jeep to work without much heat and messaging you all, the heat seemed much better on the way home. So, maybe just getting it out on the road, shaking things up a bit and letting it have a really good heat/cool cycle, helped. I checked the level in the radiator today with it cold and it is completely full. So, I'll see how things go next week. We're getting ready for Easter Jeep Safari, so I will be driving it regularly again to be sure it is ready for the long highway trip and wheeling.
 
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