The engine was a new crate motor. It is the 5.7 VVT truck engine with the 545RFE transmission. I have changed the fluid with Zerex when I changed the thermostat, but I think it was a 70/30 mix like the directions called for. I assumed that the water pump was OK since it will cool off when I run the heater. I have an AEV front bumper with a 9.5 warn winch, it doesn't block the front that much. Also I had this problem with the stock bumper installed until march. I'm not getting any trouble codes, and I get readings of the coolant temp with my scan tool hooked up. I really like the power I have with the engine, but I wish I would have gone to one of there competitors at this point. I think it must be the radiator but I want to check every thing before I go that route.

 

I have a feeling it is the radiator and fan combination that you are running but an improper program could also be part of the issue as well. You could change the radiator and fan and still have an issue if it is running the wrong program.

 

Have you seen this thread ---->> https://www.jk-forum.com/forums/modi...emi-jk-277352/ ?

There have been a number of threads around the different JK forums discussing your exact issue. Good luck.

 

I'll check it out, thanks

 

Sounds like your hemi is "bad"! We should meet immediately and I will swap my 3.6 for your Hemi. I mean what are fellow Jeepers for, right? Haha

Sent from the fast lane while driving one handed.

 

I have the 6.0L LSx conversion (versus the Hemi), but it's still a V8. That said, any V8 produces a lot of under hood heat. I opted for an aluminum 3-core radiator (Griffon, I believe) when MoTech did my install. A large radiator makes a big difference. It runs the stock fans, but does not overheat..... and I've driven it both interstate and off-road in 117 heat here in the Cali' desert.

When my swap was done Robbie told me that Hemi overheating is a common issue. Not sure the cause, but I'd assume a fatter radiator would be a good starting point.

Good luck

 

Have you made sure your fan shroud is doing its job correctly, and that all of the air coming through the grill is also coming through the radiator? Maybe an AEV heat reduction hood would help. The heat reduction hood takes advantage of the low pressure area just behind the front of the hood to draw more air up and out of the engine compartment, which also draws more air through the grill, and hence, through the radiator. At least that's what they say it does.

Good luck. Your problem sounds fixable. Worst case scenario would be a larger capacity radiator.

I'm not having any overheating problems with my 6.4 hemi, but reading these threads about other people having problems makes me worry.

 

this was a common issue with my old xj

Change out the radiator, and use a double fan setup.

When i did this, i never had another issue

 

It's really common in the hemi swaps. If your airflow is ok and everything is mechanically ok, then the rank order of issues in my opinion is:

1. Weight. Get your rig down as light as possible. 6500 lbs or less if possible.
2. Proper gearing. 5.13s work well.
3. Bigger radiator. Ron Davis and Jeep Speed Shop both sell radiators that work with JK that are bigger than BOR or AEVs. Lots of us here in CO have switched radiators.

 

It looks like I run the same AEV kit and radiator as you, except with a 6.1. I still have the electric fan. In 90+ weather at highway speeds or crawling my coolant temps do not exceed 215. At crawl speeds the fan runs at high speed though, roars loud enough it can be heard in the cab. Underhood temps are pretty warm, but never had an overheat. I am still running whatever AEV programmed in back in 2009.

Something is certainly not right. No way you should be overheating with that kit and the AEV radiator in only 90 degree temps.

At a crawl, when the coolant temp gets to 212 degrees or so you should be able to hear that cooling fan from inside the jeep very clearly. In high speed mode on mine it is pretty loud and I can watch the coolant temp fall when it kicks in.

Maybe it is just a weight thing, I am still under 5000 lbs. But like stated above I would suspect the radiator if the fan is working properly.