I have a 2013 JKU with 37,500 miles on it and the heater just started losing heat temp and blowing different temps from different vents. Don't really notice much sludge in the tank. Going to call the dealer tomorrow but what's the chances they cover it under warranty?

 

I am really starting to get worried I have an 11 sport 45k and currently my heat rocks, but it sounds like it is going to be a problem, does anyone know what the cause is ?.. Anything like more frequent flush and coolant changes ?.... I would love to know what I can do to prevent this from happening

 

Figured it was like the 3.8

 

Trans cooling is outside of the radiator on the 3.8L JK, also.

The 3.6L engine is die cast, so I can't imagine how sand would get into the block, (to those who call it sand).

 

I would think that you will be fine. I also have a 2012 Rubicon soft top in addition to my 2012 sport hardtop. The sport never had very good heat, but thought that was maybe just the luck of the draw. Now the Rubicon on the other hand could cook hotdogs being held of up to the vents. In fact I toasted the 430N video once from running the heat with the 2 vents below it closed. It over heated and shut down. So I never close those now with the heat running. But the sport takes over an hour of driving to get the inside even bearable in these sub 0 temps.

Moral of this story, if you have weak heat and still under warranty, GET IT FIXED NOW or suffer later.

 

From my understanding,

The heads were made in Mexico, Mexico factory wasn't doing their job in clearing the casting sand and eventually lost the contract. Initially it was thought that this was the reason for the head failure in the pentastars.

For me when I open the radiator cap I see what looks like sparkly glitter floating in the fluid and lining the rubber gasket. I was told by a dealer that this was residual casting sand.

 

Although I did just find this...



Pentastar Engines: Production and Factory

If they are die-cast then
"During the cubing process, parts are leak tested. If any of the leak rates are too high, they are outright scrapped. If all the leak rates are low enough, they should be passed on as okay (there was a 100% impregnation rule [at Trenton] at one time, not sure of its current status).
If the rates are in a certain range, they are impregnated with silicone sealer and leak tested again. If the leak rates at this stage are low enough, they are passed on to the engine assembly plant"

So if I understand that correctly, then I might have an engine that didn't pass the leak rate and they added a silicone sealer and that could be the "Sludge" we are seeing in the reservoir.


If this is true, I foresee a class action lawsuit in the making.

 

Agreed but 'expert service writers' are telling folks the sand in heater core myth.
Keep hearing problem is varying levels of heat from different vents. That's AIR duct direction problems or just selection issues. As we all should know, the coolant only heats the heater core in the cab and the circulation fan sends heated AIR from there.
After 7 years with the Jk I found the most effective way to warm it was dash&floor setting with only the center panel vents open aimed to back area between the front seats. You can tell by the difference in the fan speed/sound that floor vents only are restricting air flow

 

This is not a fix, but in order to get some comfort from the heater I've found I get the best performance when I have the blower on recirculate. It works best when I have the floor and dash vents selected but my windows tend to fog up pretty quickly. For some reason the recirculate doesn't work when the defogger alone is selected, so the best you can do is select the floor/defog setting. Even then the recirculate will disengage after a few minutes so you have to keep turning it back on. I think this works on the principle that you're trying to reheat already moderately warm air in the cabin rather than heat cold outside air up to temperature.

I don't hold out hope for a recall anytime soon. If you're out of the 36K warranty the powertrain will not cover this repair. Unfortunately I fear that it will take someone killing themselves because their windshield was fog/iced over for a recall to be issued. Even then recent history would tell us this could take 10+ years to be issued.

I'm dealing for now, extra layers and a lot of fiddling with the knobs. Again I stress anyone who still has a warranty, whether the issue is bad or not, make them check this out.

It is a super-invasive fix, and the odds of something (else) going wrong once they put Humpty back together again I would believe to be high.

 

Recirculate doesn't work in defrost because using inside air will eventually cause fogging.
I'll have to check if mine works for a short time in floor/defog, like yours. As far as I have know, recirculate won't work in any of the defog positions.