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If you feel like it, it'd be good to get a good write up on both if these and some pics on this project. It's $175 for the kit, but IF it works in keeping the system unclogged, then it's a fair fix.
I'm gonna do the basic reverse flush of the heater core this week, as it's the least involved. Hopefully I'll 'see' what comes out of there, if anything.

(FYI, I see some people fuzzing over the clean up afterwards if using distilled water or having to blow air into it to dry it; from working on boat engines, I can tell you the easiest solution is to just to feed NEW antifreeze AFTER you are done with the flushing (right into the short hose into the core, before you remove both hoses and finish the job), so as not to leave water or air in the core, but instead it'll have (new) antifreeze. Then you can run the engine, lift the front end, burp it, whatever else you wanna do to it is fine, but you'll only have antifreeze running through the system. It might waste a bit more, but you know for sure whats in there)
Honesty - I did the flush and reverse flushes. Looking back, I should have just replaced the heater core and saved myself a lot of time.

The core is clogged. It's almost impossible to clean it. You may break a bunch of it free and get it flowing through it again... but the loose particles that are in there still will just clog up the same spot.

You'll loose heat in a few days. All the videos of guys doing the flush all have done it multiple times. It's a heater repair tease...

Just buy a core. About a foot of hose and 4 clamps. Also, drain and flush the system. Do the core swap while it's drained. Refill and enjoy.

My old heater core is drained. It weighs almost twice as much as the new one. And I flushed the core numerous times and pulled a ton of junk out.
 

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Well, I appreciate the advise. I think by now we all have figure out there are only a few possible culprits of these symptoms. I've seen the famous video (several times now) and I agree it's a great DIY shortcut that could save somebody close to $2,000 of real cash.
However, for full disclosure, I'm a pretty decent DIYer and I (personally!) also think it's a tremendous hack job...at THIS time; with a CPO Wrangler with 17,xxx miles, I'm not willing to do that. At least not just yet. I'm gonna lean on the dealer until they figure it out, AND, if it is the poorly designed heater core, they can spend the 13 hours to do it properly on the replacement while I watch Netflix and save my knuckles. We'll see. I'm actually at ANOTHER dealer much closer to home as I write this post. I'll update when they cut me lose.
 

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Just buy a core. ....Also, drain and flush the system.

My old heater core is drained. It weighs almost twice as much as the new one. And I flushed the core numerous times and pulled a ton of junk out.
Did you replace the old core with OEM again or did you go with something else???
 

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Jeep will not help you with this. CPO, new, used or not, for both my JKs I encountered the same problem. Heck, I'm an engineer and can wrench pretty well.

I swapped the coolant in my 13 really early. The original core is still in it and works fine.

I didn't get a chance to get to my 17 coolant before it was too late. (My boys play ice hockey)

Good luck bro.
 

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Did you replace the old core with OEM again or did you go with something else???
I first bought a non-Mopar core through Rock Auto for like $40. It seemed odd when it arrived (the hard lines move where they connect with the core) so I returned it. I then bucked up the additional $30 for the Mopar core.

Turns out, the lines being able to move was normal. That said, the two cores seem to be the same. I didn't cut through the core to fully examine.

But yeah, I replaced the core with another Mopar part.

On my 17 I went with the Prestone coolant. My 13 I had the dealer service department do a power flush for like $100. They replaced the coolant with the Mopar stuff. The added stop leak must be added at the factory because the swapped in coolant worked fine for my 13 for years. I later swapped in Prestone when it was time.
 

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Ok, all good advise. I'll see what they say here today, and either way I'll take the time to swap out/flush all coolant right away too. No sense in sticking with what I'm sure it's still thatfactory pink coolant in there now....
 

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UPDATE: Even thou it's been a few days busy with work, here's the update I promised on the heating issued described above. So you all know the 1st ("local" to my work area) dealer took my Jeep in and about 90 mins later started giving me the "...Hummm maybe those bumper lights were improperly installed", and "...maybe there is some plumbning missing and that's why heating if weird", and all the all-too-well-known mods vs warranty dance. It didn't go well, and I walked. Somebody here -excuse my poor memory- suggested it was probably "time for a new dealer," so I listened and I went to another ("local" now to my home area instead) dealer and expressed the same complaint about the heat only being actually HOT on the highest setting of the temp control knob.
Right off the bat, the Service Advisor was much more receptive. They knew my Jeep is a 2018 with 17,400miles and a CPO Jeep. He walked me through his best guesses (the usual stuff for this issue) and sent me to the customer waiting area. They worked on it for a few hours. Eventually later in the day, they gave me a car to go home in, and related they "needed more time." The next day I went back upon their call back, and he AND THE TECH sat down with me and explained the Jeep had 1) passed all electronic calibrations, and 2) an inspection had revealed the blend door was fully functional. He then said the heat appeared to be working properly, BUT acknowledged the temperature on the driver side and the passenger side appeared to be different. He then said in order to chase down the probable suspect issue - 3) the electronic unit head itself - they needed to follow the wiring back to the front of the firewall, where the 'brain' is located. The ONLY time the "mods" came up now, is because I have a Genesis Dual Battery System, and a Docking Station on the dash, plus HAM and CB radio hook ups. In order to chase this issue, the most of the dash needed to be removed. The tech said the unit itself WOULD totally be under warranty IF defective (they were not sure at this point), and so would be all the labor to remove and re-install everything. HOWEVER, removing all the after market modifications installed by me would not, meaning the labor to remove everything and then put it all back would be labor out of my pocket. I'm not going to lie: THIS particular part of the explanation did make sense to me. The S/A also said they felt my work was very clean and proper, and they couldn't guarantee MY previous quality of work. They also gave me a choice to remove everything myself and bring it back.
We discussed the coolant with the suspected stop-leak from factory, and they both really said it wasn't so. This newer coolant has been a solid performer (In their view at least), and told me there was no need to flush it. We talked about the heating core and they both related if that was the issue, I'd have NO heat at all. This is not the case. They would have no issue warrantying that work too.
So....I received a little more "training" on the use of the AUTO feature and also on the use of the heat HAHA. I felt pretty douchy. But when inspected closely, you admit its not a Lexus 470 where there is DUAL heating controls. It seems, like a bunch of you have reasoned here- that the temp dial is not a specific exact temp, but mostly a guide and a range of heating. I seem to feel better about it now that I expect certain things at certain levels of the dial.
Anyway, that's it. That's all I have.
 

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It's the core. My 2017 has a manufacture date of June 2017. Really didn't get much newer - I know you have an 18 - for the JKs as they ceased making the JKs in April 2018. That said, your issues are exactly what a clogged core are. They're pulling your horn with the electrical stuff. The 2018 JK was the 12th year of the JK. THis isn't a new issue.

The fact that they suggested some kind of electrical issue is an insult. You mean to tell me in less than 2 years there were issues with the electrical system? I'd be more mad if that were the case than some crap in the coolant clogging up the core.

The coolant flows into the core from the passenger side and exits on that side too. The driver's side is a low flow area by design. The clogging material will settle there and stick in the narrow passages. Meanwhile the coolant pressure is able to get by on the passenger side still and therefore heat on that side stays warm.

The air flows through the core like it flows through your radiator behind your grill. There are air ducts directly behind the core that take the air that passes through the core to the respective side of the Jeep. This is why the driver side air isn't warmed as it passes through the core. The core on that side isn't warm.

When you run the fan on high, I think there is so much air being pushed through that you get some back flow and mixing at the core before it can go down the chutes to the sides of the cabin.

It's like everyone trying to get through the gate at the baseball stadium at once.

I posted pictures of the crap that's in your coolant. Mine is the same as what's in your Jeep. Did you look at the overflow tank? It's a similar low flow area as your heater core. It's basically the other end of the system just without the narrow passages. Look how much crap settles there then hardens up (it's a leak stop). The same if not more is happening in your core.

I've been busy around the house. I'll cut my old 2017 core in half and post what all has happened to the innards of that here.

I have some of the stuff from my overflow tank saved and fully dried out now. It's like a sticky sandy putty. That was from just the Mopar coolant that came from the factory.
 

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Also, the blend door thing is so wrong. If there was an issue with that, the entire cab would be blowing the same temperature. The JKs don't have dual zone climate controls like other vehicles do. There are separate blend doors for driver / passenger for those vehicles. The JKs don't have additional blend doors.
 

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Yeah, I get it. It all makes sense. (Althou Im pretty sure theres another blend door right behind the glove box, to the left- no matter, JK does not have "dual zone" anyway)
Well, the thing is if it's the heating core and half the car has to come apart to do it as the dealer book calls for, THEY are not gonna deal with the aftermarket parts I've added to it. From the legal point of view, I can't see them taking on the removal/re-install responsibility.
On another related topic, Id like to hard- flush the entire system and hopefully clean it up. What OTHER coolant to use other than the suspected Mopar factory problem coolant???
 

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It's the core. My 2017 has a manufacture date of June 2017. Really didn't get much newer - I know you have an 18 - for the JKs as they ceased making the JKs in April 2018. That said, your issues are exactly what a clogged core are. They're pulling your horn with the electrical stuff. The 2018 JK was the 12th year of the JK. THis isn't a new issue.

The fact that they suggested some kind of electrical issue is an insult. You mean to tell me in less than 2 years there were issues with the electrical system? I'd be more mad if that were the case than some crap in the coolant clogging up the core.

The coolant flows into the core from the passenger side and exits on that side too. The driver's side is a low flow area by design. The clogging material will settle there and stick in the narrow passages. Meanwhile the coolant pressure is able to get by on the passenger side still and therefore heat on that side stays warm.

The air flows through the core like it flows through your radiator behind your grill. There are air ducts directly behind the core that take the air that passes through the core to the respective side of the Jeep. This is why the driver side air isn't warmed as it passes through the core. The core on that side isn't warm.

When you run the fan on high, I think there is so much air being pushed through that you get some back flow and mixing at the core before it can go down the chutes to the sides of the cabin.

It's like everyone trying to get through the gate at the baseball stadium at once.

I posted pictures of the crap that's in your coolant. Mine is the same as what's in your Jeep. Did you look at the overflow tank? It's a similar low flow area as your heater core. It's basically the other end of the system just without the narrow passages. Look how much crap settles there then hardens up (it's a leak stop). The same if not more is happening in your core.

I've been busy around the house. I'll cut my old 2017 core in half and post what all has happened to the innards of that here.

I have some of the stuff from my overflow tank saved and fully dried out now. It's like a sticky sandy putty. That was from just the Mopar coolant that came from the factory.
Well, I gotta stop fighting it. I did a hard core reverse-heating-core flushing today. I could clearly see a LOT of sediment flowing out onto the bucket. Too fine to feel like sand on the bottom of the bucket, but I could easily see it going out. Every time I swapped between regular flush and reverse flush, you could see more and more. I even ran some CLR through it and let it sit for 30min. Man, ridiculous the amount of more and more sediment that came out. After of about 90 min of flushing and prolly 50 5-gl buckets out to the street (It was just water, there were only 2 buckets with the coolant currently IN the core at the time of start up) I could see very little sediment flowing through it. Still there, but I didnt want to keep going. Anyway, right after re-fill and hook up I fired up and sure enough had great heat on ALL settings of the dial....Mission accomplished! Victory!



Well ****, victory is a funny word. 'Cuz about 2 hours later while driving on the highway at 75mph it is back to the same issue: Great heat ONLY at highest setting of the knob. EVERYTHING else back from highest setting, yields cool air.
Fan works great. 1st setting is low. High setting is wicked fast. Check.
Selector works great. Floor is floor, dash is dash, and defrost is defrost. Check.
Temp-selection is off. 66-68-70-72-....78-80-82 ALL cool...84 = Lava hot!

So there is it....
 

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Been there before. Honestly, popping in a new core and completely flushing and refilling the system isn't hard. Just get a decent battery powered oscillating tool and it will go easy.

Just make sure you drain the system well before cutting into the line in the cab. Also, pull up the rug on the passenger side. 5 minutes of work in case any smelly coolant oozes out. Put a few dry rags there to catch anything.

The videos are spot on.

I have a Ridgid brand tool. I use it for wood work around the house (cuts baseboards for hardwood floors, etc.). Any similar tool would be perfect.

1590005326708.png

I've had mine swapped since the start of the covid lockdown. Did some road trips and all since then without issue.

My wife and kids would complain that I was "cooking them" while driving all winter. Driver side was never the same heat as them (even with the flushes). After the new core... I'm now constantly turning down the heat now.

Heater Core + 1 foot of heater hose + 4 clamps + new coolant + 1 hour of work = heat again
(I'm teaching my kids all kinds of math now...)
 

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You should be around 125-140 degrees out of all the vents with the heat on high. Maybe a little more.

After my several flushes, the leftmost dash vent would get near 100. But it would settle back down to what feels like ice cold at 80 degrees in a day or two.
 

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Well, when I go to that highest temp setting, I get lava hot heat out BOTH the driver's side and the passenger. No doubt there. Then I back off even 1 click and its all cool, all around.
After the mini reverse flush yesterday, not only I saw a bunch of s**t come out, but immediately after I had great heat all around on ALL settings again....for about 1 hour. Then back to "incredibly annoying issue #1"

So I went to my buddy's shop today. Independent shop now, but worked at Chrysler Jeep Dogde dealer for several years. So did the the guy he "stole" from the dealer to open his own shop. We all discussed this issue at length.

They schooled me on the very classic heating issues on Wranglers; VERY common, even on Jeeps like mine with 18,000 miles:
1. Blend door failure or re-calibration issue (driver's side actuator),
2. Fan speed or selector actuator (passenger side actuator),
3. Auto Temp head unit failure (the entire unit has 2 plugs and they def fail!)
3A. Resistor unit linked up to head unit.
4. Low coolant and/or air bubbles in the system (no/low heat)
5. Clogged heater core (debris in the fins, while allowing some decent amount of fluid pass through the lines)
6. Heater Core failure (NO heat + coolant smell + leaking coolant on passenger rug)

They were very clear on 2 things: ANY air on the system will cause problems, and there are many places for air to hide in this particular Jeep set up. And no, it doesn't "work itself out" by driving around.
At the dealer level, they've heard all about the "casting sand" complaints, and also the additives used at the factory before the Jeeps are shipped out to the dealers breaking down and causing serious issues. They did advise sticking to the factory coolant, WHILE COMPLETE CRAP in their opinion, is def. a best practice.

Here's the plan of attack for next week:
As a first measure, we (by "we" I mean them- I'm done YouTubing stuff)) will do a FULL flush of the fluid. All out. Radiator, engine, overfill reservoir, and heater core. Proper tools, proper pressure, proper chemicals to the the job, proper experience. DIY is awesome, but I'm gonna go this route this time.

They will also re-visit ITEMS # 1 , 3, 3A and 4 above to make sure the dealer didn't just blow it off, in typical dealer fashion.

IF this plan does not work, it's heater core time. Aftermarket mods or not, with 18,000 miles, THEY will set it up with their old dealer's service department (different than the 2 dealers I already visited) and get one of the floor guys THEY trust to get the work order, and push it through under warranty. We'll see.
Before I get to that point, I'll likely walk away and DIY using the short cut. These guys were appalled HAHAHA but they totally understand a dealer would be 1.5 days at prolly $1800 and an independent would likely still be $1,000, AND F-up your aftermarket electronics.

So we'll see.....I'll update more when I know more. I think I'm fighting the inevitable. I just cant wrap my mind about an 18,000 mile heater core failing....without actually failing.

Thank you all for the interest and support. SOOOO many ppl have reached out and commented on this heating issue.
 

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152 degrees for me.
 

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Another date point. My rad was leaking, but luckily I got the extended warranty. I took it in today and they replaced it under warranty. I told them about a little bit of debris I saw in the coolant tank, and they refused to flush it, said flushing wasn't covered. But the debris/casting sand is no where near as bad as some of the pics I've seen on this thread. The heater core is probably fine bc the hear that comes out is super hot, and AC works fine too.

JK 2017 75th Anniversary.

Sent from my GM1917 using Tapatalk
 

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I havent tested the AC. Tech did and said it was fine🙄.
Ill try it out as soon as Chicago weather turns, prolly sometime in late August🤣🤣
 

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From what I understand,

the extended warranty is not just for the original owner.

So my oil light came on and I’m going back , in the middle of a consumption test myself , I saved this post for damn sure..
 

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THAT, I dont know about. I was just contacted by Jeep to offer me the extended warranty, and while these have worked well for me in the past saving me a bunch of money, the truth is Im already comitted to serious off roading modifications, and the idea of removing these myself prior to warranty work OR paying tired/jaded techs at the dealer to do it before they even get to the actual repairs is a no go for me.
I do understand their policies on this topic. I even find it fair. Im just not willing to do the work several times.
 
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