I had Burnsville Offroad put a 5.7L in my jeep last October, and I've had overheating issues ever since. It used to be OK if I had the heat on but now that it's summer with 90+ degree days even that won't keep it cool. I've taken my jeep back to burnsville to have them look at it, and spent hours on the phone with them but at this point they ignore me or tell me they will get back to me if I keep calling. Has anyone had this problem and solved it? I haven't been able to drive it this summer because of the problems, and I'm starting to think I will never get help from burnsville offroad.

 

Just curious but what is your gearing and tire size?

Could you add a mechanical fan or a switch to run the electric fan all the time?

 

35" tires and 4.56 gears. I'm on my 4th fan clutch but not really sure that was ever the problem, and I've got a 12" pusher fan on it now.

 

Hows the thermostat? Has it been replaced?

 

I swapped out the 205 for a 190 deg thermostat last month hoping that if it opened sooner it could keep up. It still overheats within 10 miles if my heater is off. With the heater on it stays between 220 and 225 deg when its under 80 deg outside. Turning the heater off the scan tool shows it shooting up to 238 within a mile. The ECU will shut the engine off at 240 deg.

 

I have the 5.7 VVT, 545RFE transmission, 4:56 gearing and 35's with no over heat issues at all, Knock on wood. The difference is that they installed a new aluminum radiator and an electric fan. At 102 ambient temp outside I was seeing water temps from 218 to 225 and transmission from 165 to 170. That was on a five hour trip pushing it at 80 mph. Just got through installing some vents in the hood yesterday to help with additional cooling.

 

Not sure if we have the same radiator, mine has a 35 oz cylinder on the passenger side that serves as a overflow reservoir. When was yours installed, and was it the Burnsville offroad from MN or CO?

 

Have you done the basics like changing the thermostat, water pump, and replacing the coolant by going with a 75/25 mixture of the correct Mopar or Zerex fluid? Not sure of the condition of the motor that they installed, but the impeller blades of the water pump could be worn or partially broken.

Does the Jeep have good front airflow, or is there a winch and/or bumper blocking part of grille? Was the OEM radiator re-used or did they use one of the various custom JK HEMI radiators? If it runs cool with the heater on, it sounds like the radiator doesn't have the capacity to bring down the temp of the coolant. As I'm sure you know, having the coolant pass through the heater core give you a secondary source to remove heat from the coolant.

Are you also getting a trouble code? You could have a faulty sensor. Since you have a fan clutch, I assume that they installed the 5.7 Ram truck version rather than the 5.7 Jeep or car version. Is that correct? It's possible that there is a programming error in the new computer or that the wrong computer was installed for your application. They have several different HEMI variations available now, and I could see them having the wrong computer coded for your Jeep.

It's really sad to read yet another tale of disappointment and abandonment by Burnsville customer. I'm getting close to having the funds to do my own HEMI upgrade, and I will certainly go a different route when that time comes.

 

Essentially it was the AEV install with a new larger radiator and electric fan. It was done by a local shop Screamin Lizards in Bedford, Texas this past January. It is running a new program update from AEV also.
Added a picture of hte radiator and over flow might give you a comparison.

 

Sounds like you should be on their case... if they did the swap they should know.