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Desert Scorpion 01-14-2013 03:13 PM

89' Heater Core Replacment
So just recently i noticed a leak from my heater core and took on the task of replacing it. I have done lots of book research and online searching and am confident i am doing everything right. I have undone every screw/bolt/nut/ and hoses on the engine side of the firewall that was in the general area, I have undone every cable and the defroster duct on the inside of the cab. i have pried, pulled, and tilted every way possible and the the darn thing will slide about half way out and then stop and i have no clue what the problem is... the only thing i could think of is this hard plastic tube coming down from the top of the dash on the far passenger side into a vent on the front of the Heater cover so i took off the vent cover the tube went into with no luck. what is this stupid tube? and how can i get around it??? or is it even the problem? I am completely lost :surrender: and just want my jeep back on the street. so don't be afraid to throw out any info that may be useful.

Desert Scorpion 01-14-2013 11:42 PM

Would a pic help?

Jerricho 01-15-2013 08:39 AM

Never tried to pull mine out, so I can't give direct advice on that getting it out, but the best thing I ever bought to help with stuff like this was a small dentist's mirror. I would get the core up as far as you can, then use the mirror to poke down in there so you can see what is catching. I got some at a medical supply store for a few bucks for a pack of them.

Always have one in my toolbox.

0III0forlife 01-15-2013 11:25 AM

Have you taken the passenger side of the dash apart? With it out of the way, you can see in there better. I would think its probably the wiring harness that goes to the PCM, its mounted on the top of the heater box almost straight behind the glovebox.

Desert Scorpion 01-15-2013 12:02 PM

All of the research i have done shows i don't need the dash apart. but i think i know what your talking about. its like a little box with wires coming out of it? if so its is pretty far out of the way.

kik 01-15-2013 12:05 PM


Originally Posted by Desert Scorpion (Post 3231715)
All of the research i have done shows i don't need the dash apart. but i think i know what your talking about. its like a little box with wires coming out of it? if so its is pretty far out of the way.

The heater core was replaced on my 89. The passenger side of the dash had to come off.

Desert Scorpion 01-15-2013 01:45 PM

Thanks for all the advice guys. but after some more prying and pulling it came out. The problem was the hard plastic tube it was barely blocking it so i just needed a tad more force to get it out.

BAP 01-15-2013 04:59 PM

thanks for your post,,,i think im getting ready to tackle mine,,,i have asked a question on here about help with heater,,,i replaced w/pump,termostat, and then lost heater..i dont have a leaking core, just blows heat after i shut the heater off for awhile then it cools down quickly..blowing cold air..

did you take any pics??,,,i was thinking that this would,nt be that hard of a job..


Desert Scorpion 01-15-2013 05:22 PM

now that i have done it i think i could do it again in about 2 hours. and my heater showed a significant loss in heat output before it leaked which sounds similar to your problem. although i also read a website posting when doing my research that sometimes air can get stuck in the heater core causing no heat. he said the problem could be solved by back flushing the heater core. i do not know how to do that though so i will try and ind the link for you. Your jeep is a 92' right? I will try to put together a youtube video for you with some pictures hopefully by tonight or tomorow mornin to help ya out.

89TXYJ 01-15-2013 06:41 PM

I am about to tackle mine as well, I have had it partially out before so I am familiar with the process. Quick question you have to disconnect the control cables, or can u get the box far enough out to remove the core with them still attached? If they must be removed, how do you remove the clips without breaking them? Mine is an '89 as well.

Desert Scorpion 01-15-2013 10:52 PM

Yes you do have to remove the cables or else its pretty near impossible to remove all of the screws on the back of it. all you to do to remove them is go to the back of the clip (usually the opposite side the cable is on) and squeeze the clip with needle nose pliers and pull the cable out. hopefully that helps ya if not i should have pics and maybe some video up tomorrow that will give a better visual of the layout.

BAP 01-16-2013 06:40 AM

thanks scorpion,,,,,,rite or wrong i flushed my h/core by taking the hoses that go into the core off and run water threw them with low pressure frome a garden hose untill clean water came out the other hose,,,mine was very very clean,,,i excpected a bunch of junk to come out but it did,nt just had a slight discoloration the quickly ran clear..

thank you for taking time to post up links for us...


Blackjack93 01-16-2013 09:15 AM

this might help Heater Core -

BAP 01-16-2013 10:27 AM

thanks blackjack,,,at least i kinda know what to see in there...

sorry i dont mean to high jack this thread....

Desert Scorpion 01-16-2013 01:30 PM

Back flushing that Jeep heater core. - YouTube
here is the video link to the guy who back flushed his heater core in case anyone still needs to.

Desert Scorpion 01-16-2013 02:27 PM

Heads up on anyone who replaces the blower motor too. the standard blower motor for jeeps between 80's and 90's is a larger upgraded one and you will have to cut a bigger hole in the firewall for it to fit. the original factory one has been discontinued. also there has been some arguments made on whether or not brass and copper heater cores are better than aluminum or vise versa. Does anyone know for sure which is better? the original factory one i had was brass/copper so i got another brass/copper since it seemed to work pretty well. P.S. still working on trying to upload a video.

BAP 01-16-2013 04:21 PM

i watched that same youtube video,,,,and a couple more that said to run crc or kerosen threw it,,,but i just used water..

i reflushed mine this morning and this time i got alot of brown water out of it,,i kept doing it untill it was clear,,,now i have heat again,,,,i ran water threw both hoses with a stronger blast evry now and then....

i have ran it all day and still have great heat,,,--i may have to replace the core before it,s over but man im glad i did,nt have to do it

thanks to everyone,,,,---and again sorry about high jacking your thread...

teardropty 01-16-2013 04:36 PM

We always run a mixture of vinegar and dawn dish soap into a heater core, let it sit overnight and flush in the morning. Of course this is only if the heater core is disconnected from the rest of the heating system. Just redid my heater core in my '95, got a new lifetime warranty heater core from rockauto for $28 shipped. Was worth putting in new once I spent all the time dropping the heater assembly out. The hard part for me was getting the assembly sealed back up and getting the little flapper peg back in the right spot. Those of you that have torn one apart will know what I mean. Have fun!

Desert Scorpion 01-16-2013 05:23 PM

89 jeep heater core overview - YouTube
I did a little video for anyone who needs more of a visual. and BAP don't worry bout hijackin the thread im glad you can use it.

Blackjack93 01-17-2013 09:55 AM

back in the day farmers used to flush out thier radiator with coka-cola, hate to thick what that stuff does to your gut

needforspeed150 01-17-2013 10:45 AM

Thanks DS for the video. Good info. I always check out tech stuff because sooner or later I'll be doing it.

BAP 01-17-2013 10:51 AM

thanks scorpion, that was a great video,,,im going to save that on my computer for when my time comes...

coka cola was used by dentist back in the day for numbing,,,henc coke,,,wonder what the ingredence,s were back then---lol

when i was young it did a great job on corroded battery terminels and we used it to shine our tires before armoral came out...


Desert Scorpion 01-18-2013 04:08 PM

If anyone is going to replace the heater core! replace the blower motor with the new upgraded one! i used to not be able to defrost my back window but with the new motor it will defrost in about 10 minutes! It is so much more powerful!!!

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