Hey guys, I have a 2011 jku. About 3 night’s ago in the blistering queens nyc cold, my Jeep overheated on me. Saw the smoke,heard the radiator making weird noises.... called my mechanic and took it to the shop the next day. He ran everything and it worked fine, we even changed the relay switch for the fan and the cap.... after leaving the shop, 30 mins later it overheated on me again. Yesterday we changed the coolant temp sensor and the same thing happened again, it over heated. I also noticed that before it over heats my check engine pops on and it gives me p1745 trans pressure to too long. Basically putting my Jeep into limp mode and not shifting into 2nd or 3rd. today I’m gonna replace the water pump, and the thermostat. Is there anything that I’m missing ? Hope this saves my Jeep. Please any help is much appreciated.

 

Is this overheating when siting still or moving? You can tell pretty easily if the water pump/thermostat is working by getting it to operating temp and just feeling the hoses. I assume the radiator cap was replaced and the fan has been checked out. Both of these can cause overheating. I assume the mechanic checked the oil and you don't have a head gasket leak. Not as common nowadays is simply that the water jackets are clogged but that isn't common anymore. Let us know what you discover.

 

Yea, it over heats only when driving, running still doesn’t over heat. Fans come on to. Actually changing the thermostat and water pump as we speak. Hopefully this solves it. Will keep you posted.

 

Great let us know what happens. I have seen where the fan doesn't turn off which causes overheating when driving as well.

 

I am having the same problem with my '10 JKU. I have only changed the thermostat so far. I think that I have a small hole in my radiator and I am thinking about using Bar's Leak Liquid Aluminum to repair that. I have checked the oil and there is not any water in the oil. Any advice would be helpful.

 

Lot of times those radiator leaks are hard to spot with everything in place. They are typically at the driver's side where the fins meet the side. It takes about 10 mins to pull the airbox and intake boot, then remove the couple bolts that hold the fan shroud to the back of the radiator. You can then lean the shroud back and get a good look at the back of the rad. It should be pretty clear if it's leaking or not. Even a tiny pinhole leak will make a mess over time. The issue is those leak typically burn off before it gets to the bottom of the rad so you never get to see a drip from the bottom or evidence on the ground. My old factory radiator passed several pressure tests. I decided to just replace it anyhow and upon disassembly, it was as obvious as could be that it was bad. Best to just do a quick visual inspection.

 

Thanks for the info. I will check that out and see what I find. Would you recommend using Bar's Leak?

 

I’ve never felt good about using leak repair products or putting foreign substances in a cooling system. That is just my opinion though. The better solution is to pinpoint the issue and correct it rather than blindly try to throw a bandaid on it.

 

Any Updates?

 

The radiator end caps are a pretty common problem on all JKs. I know I chased mine tirelessly on the 3.8L because what typically happens is no leak when sitting still. Then radiator heats up and gets under pressure while driving which causes the end caps to expand and expose the leak. I ended up going to Harbor Freight, purchasing their radiator pressure test kit where that puts the radiator and entire coolant system under pressure while sitting still and that exposed the radiator leak for me, steering me to replace the radiator. Another common problem on the 3.8L is the Lower Intake Manifold (LIM) gasket. Similar scenario, no leak detected when engine is cold, then heat of engine expands and starts leaking from around that gasket while driving. That one is harder to find with a pressure tester. Typical case is that if no leaks show their face while doing a pressure test, then it's likely the LIM gasket.