This post is my attempt to describe the process of replacing a thermostat housing on a 2012 Jeep JK with a 3.6L V6 Pentastar engine.
The primary function of a thermostat is to maintain a minimum operating temperature in your car’s engine. When you start your engine cold, antifreeze / coolant mixture is kept within the engine by the thermostat. When the coolant temperature reaches the specified opening point of the thermostat, it opens. Coolant will then flow through the radiator to keep the engine at a temperature close to the rated temperature of the thermostat.

The reason I needed to replace my thermostat was because one morning while driving to work, the “check engine” light came on. When I got home I plugged in my Flashcalto read the code. It was a p0128 code (an indication of a faulty thermostat or ECT – engine coolant temp sensor). After talking to few people I decided that the first thing I’m going to replace is a thermostat and see if that fixes the problem. I got the new thermostat housing and a gallon of coolant at my local dealership.

I own a 2012 JK so that’s the last model year that uses the HOAT coolant (Mopar part number 68048953AB, label on the bottle states 5 Year / 100,000 Mile), and this is what this post is written for. The procedure for Jeep JK thermostat housing replacement is the same for either type of coolant though.
Also if you buy concentrated coolant, you need to get a gallon of distilled water to mix it with, before adding it into your cooling system.

If you plan on doing a full flush of your cooling system, make sure you have enough fresh coolant before you start. I believe the entire system uses about 3.5 gallons, but you need to refer to your manual or talk to a Jeep mechanic to confirm.

There's too many steps and pictures to paste them all in here.
You can find the full post with all details on my site:
https://azoffroading.com/blog/jeep-j...g-replacement/

Here are few photos to give you the idea of what the project is about:

 

Really nice write up! The hardest part for me was the top inner fastener since it’s at an awkward angle.

DIY how to:

 

Good write up. I had to do this on my wife's 2012 Cherokee as well.

 

Nice. The thermostat is easy. I did the water pump which is easy too but broke a fastener in the block so I had to extract it! What a pain that was.

 

What is the reason for replacing the housing and isn't there a gasket? If the thermostat needs to be replaced do you have to replace the housing too? I haven't done this on my Jeep yet but on my old Ford Bronco I just replaced the thermostat and gasket.

 

It's a complete unit with the thermostat built in to the housing. I believe I have seen before someone being able to just replace the thermostat, but it's not worth the effort on these JKs. The whole unit is cheap.

 

Since I was changing the thermostat I decided to do the housing as well since it was off. The thermostat came with a gasket and the housing was separate. They were both well under $100 so pretty low cost.

 

on the 3.6 the tstat and housing come as a unit and there is an oring that comes with it there is no other gasket needed. An OEM part should be under $50 complete from your dealer.
https://www.moparfactoryparts.com/oe...SABEgJYvPD_BwE