Rednroll

Here is the cross sectional dissection of my old heater core. Mine wasn't clogged with hard calcium deposits like B.Law's as shown in his OP. It was more like clothes dryer lint fabric material was caked in there. It was clogged up more on the driver side which is common with B.Law's.

Top full view


Bottom full view



Top zoomed


Bottom zoomed

Rednroll

As an additional note for anyone doing this heater core swap method. I think where the cage repair is most important is when you go to fasten your glove box trim back together. There are a total of (5) 7mm screws that hold that trim down. (4) of those screws are the frame for your glove box where (2) of the trim fastening points are located on that cage section that you have to cut out. I used ratchet straps to pull that trim out of the way so I had room to work. Well, having it pulled like that bent the trim out of proper alignment and being able to fasten the trim back to those 2 anchor points on the removed section of the cage, pulled the trim back into alignment so it looked right and your glove box opens/closes properly. I would have to think without doing the cage repair, you may run into problems where your glove box may not open/close properly when put all back together.

An additional tip on the cage repair. There is a bracket on that cage section that I cut out, that holds the cage to the dash. There's a single 8mm bolt that holds that cage to the dash. B.Law cut to the left of that bracket so the mounting bracket was still in place. I cut to the right of that bracket, so the bracket came out with the cage section that was removed. I think cutting to the right of that bracket is important, since that will assure that those (2) trim mounting holes that are located on the cut out cage section, are still properly aligned with the trim mounting holes, so everything is properly aligned during the trim re-assembly.

Here's a pic to better show what I'm describing.

Four Low

So what is this material clogging the HC ? Do you think its in engine cooling system as well ? OAT vs HOAT coolant ? The faulty elbow joints should be a Recall or warranty item.

Rednroll

That's a good question. I think the internal fluid slots in the heater core are the smallest passages in the entire cooling system, where they are just too small in my opinion. So any material debris that gets into the cooling system, the heater core acts like a filter and eventually clogs up. Now how that material is getting into the cooling system and where it comes from, I have no idea. B.Law's clogs were calcium deposits, and he was using Zerex. My clogs were a lint type of material. I have a 2009, I've only used HOAT and I've only used Mopar HOAT when I had to replace any, where no one else has ever topped off my engine coolant. So I can vouch that my cooling system has only seen HOAT which has been mixed with distilled water.

Edit: I just cut my old core right down the middle so I could see how clogged it was in the middle and split open the tubes that run through the core that the coolant should be running through and scrapped out some of the debris stuck inside of the tubes. It felt very gritty when I rubbed the debris between my fingers. So, I'm going to further speculate and say it seems to be engine casting sand. I would have to say, what seems to be happening is that the core is acting as a filter as I previously mentioned and ANY casting sand that is in the engine eventually gets trapped inside the heater core. The more casting sand you have left in your engine from the factory, the sooner your heater core will start to malfuntion. Your heater core is essentially working as a filter, where that filter will eventually need to be replaced. I got over 100K miles before I noticed my heater not working up to par. I suppose it could take that long before any casting sand circulated from the engine and got fully trapped inside of the heater core.

lschif

Thanks to B.Law and Rednroll - been living with a bypassed core (leaked at the bottom fitting like many others) for the past two years. I couldn’t pull the trigger on the 1300 that the dealer wanted for the heater core replacement. This hack was a thing of beauty - thanks again.

karls10jk

I need to put an actual thermometer on my vents but I'd bet my temps are right with yours (Rednroll) without replacing the core...yet.....but I also changed my coolant and cleaned the casting sand out of the radiator overflow bottle quite a few times. Coolant was changed at 100k and the bottle was cleaned probably 3 times in that mileage.

Who knows?? but I'm appreciative that someone else has taken the time to document an easier/ better way to do it.

Rednroll

Looking over what is needed to be done to replace the heater core by removing the dash and all the other stuff, I think I prefer this method even if I had $1300 to throw away on replacing a $75 part. I would have to think once you take all of that apart, there are bound to be loose screw fittings and such.

I was initially worried about cutting out that piece of the dash cage in regards to the dash structural strength but now that I've done the repair and feel how solid it feels when I put it all back together, I have no worries. I would recommend doing the cage cut-out over pulling the dash out.

pyite

I have this same damn issue now. 2013 JKU with 80k. Would a dremel tool be able to cut the piece out?

Rednroll

I used a HF 4 1/2in angle grinder to cut out the dash cage section ($10). A dremel may work, but the difficult part will be cutting the lower section by the floor. It's kind of hard to reach a tool in there, where it would seem a dremel with a cutting wheel, the tool handle will most likely be turned sideways where there likely isn't enough room to fit it in that way, so I doubt it . The cutting part of my angle grinder barely reached, going straight on at it.

I can say for certain this will work.


I used an oscillating multi tool with a half moon hack saw blade on it, to cut the heater core tubes.

GileadGarage

Hi All, first post here. Bought Wife 2013 JKU since she insists on Manual transmission, and not many 4x4 manuals to choose from these days...

I had my reservations of buying one of these as the family DD, but she loves it so WTH... We do live on a bad road and regularly drive in mud, snow etc., so it is practical for us in that regard. It is stock and does not see any real off roading (for off road duties, I (gasp!!!) have a built samurai with vw diesel, but I also have a very rough 74 CJ5 plow jeep that I love!).

Anyway, it is cold here and the family truckster has virtually no heat!

Having the same issue as many: nasty looking coolant with some grit, poor heat (none driver side). I am SOL with dealer on warranty coverage so will be doing repairs myself (since when is cooling system not part of powertrain!?!?).

So glad I found this thread, definitely a better way to go even if I did want to throw money away on tearing the dash out!

My question is:

Does the fact that our Jeep has AC make a difference?

Is it the same procedure on a 2013?


I plan to change HC, RAD and oil cooler myself, and of course do several flushes prior to this work.
I spoke with dealers, Chrysler, etc and do not wish to waste anymore time dealing with them, I am more comfortable doing my own repairs anyway so sucking it up and doing this job over my Christmas vacation.

This is a huge problem fro Chrysler, which the dealer did not deny. He started to play dumb with me but quickly realized I did my homework on this disaster.

I just did all the brakes last week, including everything ebrake related. Not too bad, but have since put another project in my little shop which will have to get back on its feet and kicked out again while I am make emergency repairs to the Jeep. Oh well, the curve balls keep coming!

Anyway, I sure hope the fact that ours is a 2103 w/ AC does not change this procedure! I have not looked in there yet.

Thanks,

Mark