fprishtina

Hi all, new here. 2012 JK Sport, 3.6L

Close to a month ago I observed the following symptoms.

1. Loud radiator. It would come on after a bit of driving.
2. Engine temperature gauge was hovering between the halfway mark and H. (Fourth line from C, one away from H).
3. Sloshing when I turned the car on and it was mainly heard on the passenger side.
4. No heat from heater. Cool air worked but heater would just blow room temp air, unless I was accelerating.
5. Empty coolant tank.

Actions taken to fix.

1. Filled engine coolant tank to max line. (This did not solve any of the symptoms above).
2. Burped the system. I bought the funnel and more coolant. I parked the car on an incline and opened up the radiator cap. Air came out as soon as I loosened the cap. I put the funnel in, added coolant and watched the air bubbles come out until it stopped. I also squeezed the big radiator hose a few times for extra measure. I closed the radiator cap.

This seemed to have fixed all the symptoms above. I was keeping an eye one it for the last three weeks. As the days went by I could hear/feel the symptoms slowly coming back. This morning it was very clear that they were back without a doubt, except for #2. Engine temp is still hovering at the halfway mark.

I plugged in my JScan to check any error codes and monitor engine temp. No error codes and engine temp was 190-220. For about 20 minutes of local driving. I used my funnel and remaining coolant to burp out the system again. Some burping, not as much as the first time though. The overflow tank level did not look like it dropped from a month ago.

It seems like there is a leak somewhere or air is getting in somehow. Anyone out there that can help me with the next steps to diagnose and fix this? Many thanks.

resharp001

Yup, you are definitely getting air in the system somewhere. The most common things would be a slow leak at the radiator (often driver's side where the fins meet the plastic side cap) and the thermostat housing. I would take 10 minutes, remove the air box and tube to the intake, remove the fan shroud out of the way so you can see the backside of the radiator. any leak there would be apparently with dried coolant on the fins. Often this is so small and it dries so fast you never see a drip to the ground. I would inspect the thermostat housing very carefully for any sign of leak.

Presume you have no leak at the heater core in the cab or else you'd smell it, but you might just double check passenger side footwell to verify no signs of being damp. Another area it could leak would be the oil cooler housing which sits under the intake and in the valley of the engine. No way to really inspect this without ripping the whole intake off. The other thing would be a headgasket leak. You could do a combustion gas test if it gets that far, but check the obvious things first. Can also inspect the oil for any sign of coolant mixing in.

Start with looking at the most common and obvious things first though.

fprishtina

I see, so next step would be to take a look at the radiator and thermostat. One question though, is dried coolant easily identifiable? How would I know that's what it is if I do see something in the radiator / thermostat housing?

resharp001

It should be pretty obvious. Your '12 had HOAT coolant in it originally, which was an orange color. That might have been changed to something else in the last 12 years, but either way any coolant is going to have some color to it and it's gonna be kinda crusty when it dries.

here is a picture of my factory radiator back in the day. Keep in mind that this leak was not big enough to ever drip to the bottom or leave anything on the ground. Also couldn't see any of that until the fan shroud was out of the way. (my OAT coolant is purple) -

fprishtina

Update on this. Today I was able to take a look at the car. I did not take things apart to look at the entire radiator. I only pointed a flashlight at the hole where the reservoir tank attaches. From what I could see, the radiator looked fine, no residue, no build up anywhere. I watched a few videos etc and it looks like the thermostat is working, the reservoir tank has not gone down in level at all.

One thing people mentioned is the radiator cap itself. Given this is a cheap option, I will buy a new one and see if that fixes anything. If not, then I can try and take apart the radiator for further inspection.

Jay2013jk

When buying a new Rad Cap.. GET a MOPAR Cap correct for your Jeep.

fprishtina

yeah I went to mopar store and bought one using my VIN. Apparently it’s this 17lb one, Mopar 4596198.