Coolant Flow through Heater Core
 

On pentastar 3.6 does coolant always flow through the heater core or is it only when the heater switch is turned on?


The reasons I am asking is because I was running low on coolant, and decided to stop by at the dealer to purchase more coolant. According to the dealer my Jeep use OAT coolant (2013 JK), but when I remove the radiator cap the coolant had an orange look. Which to my understanding that is HOAT coolant. To play it safe I decided to flush the coolant before adding new coolant. This is what I did:


1. I drain the coolant from the radiator drain cap.

2. Added distilled water and ran the jeep for 5-10 minutes.

3. Drain the coolant again.

I repeated the process above 5 time. At the end the water was coming out clear.

My concern is that I never turn on the heater when jeep was running.

You likely spent a lot of effort to drain OAT right out of there. I have a '13 as well, had same freak out as that was the year the change happened IIRC. Read a lot of stuff, but in the end got scared of the color just like you. If you read enough you'll even find a couple things saying there was OAT from the factory that was originally orange. That is not to mention that even the purple stuff looks orange when it's in there cuz the purple is just an additive.

The bigger problem you have is why are you losing coolant to begin with. We have notoriously bad rads, and I'd bet dollars to donuts you have a pin leak where the fins meet the side, probably driver's side. Keep an eye on it. You might want tot remove the plastic shroud over the radiator and inspect closely.

Thanks resharp001, I was just afraid that there was left over HOAT coolant in the heater core, due to not turning on the heater during the flush. But now I know it was just orange OAT coolant.

I don't think is leaking, the reservoir tank was low. I hadn't top it off since I bought it back in 2013. However, I will keep an eye on it.

Thanks again.

I mean, I can't say with 100% certainty that it wasn't HOAT, but if you're the original owner.....that would be a major F up at the factory, and the odds are so low....you probably would have had to be one of the very first JKs off the line and had some ignoramous there trying to save a buck with the last couple gallons of HOAT on the line. LOL. I can't say I've ever seen people with '13s that ended up having, or claiming to have, HOAT in there from the factory. I was in the same situation though, and I did the same thing just for peace of mind before I determined I thought I just wasted a lot of time.

If you find yourself having to top off the coolant res every month or two.....that's when to start searching for a leak. Just keep an eye on it. Even when I was certain I had a leak somewhere, it took a long time to see visible signs.

The coolant always runs through the heater core. There is no open/close valve going to the heater core on our JKs, so you are good on your flush.