As the heat & defroster continued to get worse in our 2008 Wrangler JK, after multiple HC flushes, and after much research on here and elsewhere, I realized it was time for a new heater core. Guess I can't complain, she's got 160K on the odometer, so the time had come. Yes, there has been a few other write ups about changing the heater core, using both the "official" and "cheat" way, but thought I'd do a quick one with a few pics, hopefully my experience may fill up any questions some may have.

After realizing replacing the heater core could cost upwards of $1000 locally, I was looking for some possible hints on how to do it on the cheap. After watching different videos, I KNEW I wasn't taking the entire dash board apart. Luckily, I came across this video on YouTube ( ), which is exactly what I followed (well, almost). Instead of draining all the coolant out of our Jeep, I made these "plugs" out of 5/8" hose and 3/4" plugs.

Makeshift "plugs"

I used these on the lower engine block where the coolant travels from the heater core (let's call it "HC" for ease) and on the water pump, once disconnecting the hoses to and from the HC. This way only a very little coolant is lost. In hindsight, I could have simply used one 5/8" plug on the water pump instead of the longer hose version. I think the hose plug version is needed on the HC return to the engine; it's tight spacing to get in there (BTW, I accessed that area after taking out the passenger front fender liner; it's behind the shock tower).


Heater Core return line, behind shock tower. My Rugged Ridge snorkel intake is in the foreground.

Once these "plugs" were in place, I simply blew air (using my compressor) into the top HC line (where it was hooked up to the water pump) to evacuate the coolant remaining in the HC.



Now it's time to pull back the passenger portion of the dashboard. There's only five 7mm screws that need to come out (as shown in that video). Then remove the glove box, lower panel (it just pops out) and side panel (same, just pops out).



Then pull the dash out so you can get in back.



Next, you'll need to remove the passenger floor duct. No tools needed, just a little tug and twist.


Remove the floor duct

Floor duct removed

Now we can see the HC.

Heater Core & pipes now visible.

You'll also see the dashboard frame now. As mentioned in the video this has to be cut in three places. I purchased an oscillating saw for this from Amazon; about $60 and well worth it!



Now there's two 8mm screws to come out:



The cut dashboard frame is now out.



We can now see the full HC. You'll have to now cut the two HC lines, watching for the movement of the whiteish oval heat duct selector; this is why I cut lower than some other. In the 2007-2010 there's also a wire harness to come out; it's on the firewall and very easy to remove (pinch from the bottom and pull). From the videos I've seen, this wire harness isn't at this location in the 2011-2018 JKs.



Heater Core simply slides out once the pipes are cut.

Genuine Mopar Heater Core 68004193AB from Rock Bottom Auto on Amazon ($64)

Now, take the old HC and compare where the pipe cuts are an cut in the same places on the new one. Make sure to debur the inside and outside of the new pipe cuts. BEFORE cutting the new HC, flow some water (not on high) through the top pipe and make sure it comes out the bottom pipe. It would suck to go through this project to install a bad heater core.

Once the new cuts are ready, cut some 5/8" ID radiator hose into two 4" sections (or however long you wish). Dip the hose sections in some soapy water, and put some of that soapy water on the HC pipe ends and the remaining pipe ends in the Jeep. Push the hose pieces onto the new HC pipes, and slide two hose clamps onto the HC pipes. Make sure to align the worm screws so you can access them once installed.
Slide the new HC into the slot in the dash and push the hoses onto the old pipe ends, then tighten the hose clamps.



Now, put the cut dash frame section back in and screw in those two 8mm screws.


Cut dash frame back in place

Put the floor duct back in and reattach the wire harness. Screw the five 7mm screws back in. Remove the "plugs" from the water pump and engine block, and refill the coolant (proper 50/50 mix using the correct coolant fill procedure).
Hope this helps someone. This entire project, including the heater core, hose, clamps, and even including the saw cost about $150. Total time from start to finish; 3 hours, but could be much quicker.

 

Thanks for the detailed write-up. What exactly lead you to believe the heater core was the issue? I am currently battling a heating issue myself. The defrost on the passenger's side is acting up. It isn't blowing as much as it should and what is blowing is lukewarm whereas the driver's side is piping hot. Also, I can faintly smell antifreeze and have what looks like smoke/condensation coming from the vents/floor for about 4 or 5 minutes after the jeep warms up. I am forced to roll the windows down until it clears out. Since the passenger's side isn't working correctly, it fogs up that entire side of the jeep. I have to top off/burp the coolant every 5-6 days. I think both the heater core and the blend door actuator are both bad. I flushed the heater core, but really didnt get anything to come out. I have a 09 jk with 180k miles. My guess is the heater core has never been changed. Any feedback would be appreciated. Once again, thanks for the great write-up

Jeremy

 

My heat was blowing cool on driver's side and luke warm on the passenger side. The defroster was worse. Multiple heater core flushes didn't solve the problem. Post replacement, piping hot on both sides now.

Although I'm not expert at this, I'd say your heater core is bad, and leaking coolant into the vent that's smoking. It's probably clogged plus had a small hole before the blockage.

 

Thanks for adding this write-up. There are scraps of this process out there on a few threads, but this is nicely organized and well documented for someone to follow.

 

After changing the heater core and tweaking the new heater core clamps, (small leaks) I'm happy to say I have great heat again. Thanks again for your write up!

Jeremy

 

hello guys
sorry for my english, i'm french..
i have a jk 2010 CRD2.8 same heat problem , still warn but never the normal hot temperature
before changing the heater core, i would like to flush it
the problem is that , there is a lot of video for US JK in 3.8 gasoil , but in the 2.8CRD, the motor seems to be higher and not possible to access to the 2 hoses near firewall
so my question is : is there a way to follow the 2 hoses in order to disconnect them elsewhre in the car in a easy spot to work ?
i have never find any pictures for that
thanks for your help
rgds

 

Thanks for the detailed repair I replaced mine the same way and it was very easy the only issues I had were the hose clamps held off the floor duct and the dash bracket I had to trim the bracket and rotate the clamps some but I have heat now

 

Thanks for this great writeup. I found it super helpful when doing mine and after over a decade of freezing my ass off in Michigan winters, I now have heat again.

I wanted to add two points that might help others doing this:

1. Make sure the new heater core will actually fit/slide into place BEFORE you cut the lines on the new one. I bought a HC from autozone, compared the new and old on my bench and since they looked identical, cut the new one. However, it would NOT slide in and a digital caliper measured it a millimeter or two wider at the widest point. Tried greasing it and a lot of force but did not want to end up with it stuck part way.... Then I bought another HC at O'Reilly and it fit perfect. (You will not be able to slide the HC in very far with the lines still intact but you can see if it will get started and might have to try it upside down.)
   
2. If you decide to do a full system coolant flush--I was at 100K so I figured it was time, you can use a length of heater hose to temporarily bypass the heater core during the flush. I used this great method for the flush (except that I drained thru lower rad hose since my drain cock didn't work) and it involves repeatedly running until operating temp and then draining the coolant so obviously you can't just leave the HC out. I didn't want to use the old HC during the flush since I figured my flow was not great and I didn't want to use the new HC during the flush to avoid lodging residual debris, etc. in the HC as the coolant circulated. I'm pleased with how it worked out. Photo below of the bypass.

 

This is such a terrible procedure to follow it ought to be deleted. Automotive engineers don’t just add 50 lbs of steel to a car for fun. Riveting or even welding that crossmember together is not doing anything except making you feel better, might as well leave it out may well be safer. Anyone who’s a proponent of this ever wonder why it wasn’t just bolted on instead of making the heater core an insane 100 step procedure? It’s because it’s important in a crash. It would suck to “fix” your jeep only to be killed or maimed in what would’ve been a little fender bender. I just hope to god no one who does this ever sells their vehicle to an unsuspecting person.

 

I guess I shouldn't have cut the front and rear frame crossmembers to install stubby bumpers and create max clearance angles.

I don't think that little piece of bracketry right there is adding much structural integrity when it comes to safety. it's really just there for dashboard stabilization, but my opinions are crap anyhow. This is really no different than any mod most people are doing to a wrangler. Lifting a vehicle, adding larger tires, adding heavy steel bumpers....these things completely change the factory safety specs of the vehicle as well. I will agree that when buying these things used, buyers should keep all of this in mind and realize they have no clue what has been done to it by a previous owner, but that is really no different than buying any other used vehicle.