Highway Overheating

Lmoye22

New member
Ok Guys I'm just about to give up and save for a V8.
So my 3.8 is overheating on freeway speeds/ Under load. ESPECIALLY on Hills!!

New -
5.13 gears
37 General Grabbers
Transmission
Torque Converter
Mishimoto Radiator
Radiator hoses
Water pump
Thermostat
Dealer coolant flush and cleaning with new coolant
Spal high performance fan
Tranny cooler


-had the jeep tested for head gaskets and chemical test on coolant. No issues


I'm using my Superchips and I'm running 190-210 all day but if I'm going over Hills or steep hills will jump it to 240. Towing my 1900lb camping trailer , JKU did fine except oninclines. 245 . Opened windows and turned on heater and came down to 210 and ran great. But I live in west Texas and it gets to 100+ . When it's heating up , power drops. Is there anything to add to the jeep to have on demand cooling for under load?


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Last edited:

fiend

Caught the Bug
Did you change your tune with the Superchips? If so try returning to stock (other than changes for gearing and tire size).

Also, I have read unfavorable things about Mishimoto radiators. If you have or can get a stock radiator, try that.
 

fiend

Caught the Bug
Did you change your tune with the Superchips? If so try returning to stock (other than changes for gearing and tire size).

Also, I have read unfavorable things about Mishimoto radiators. If you have or can get a stock radiator, try that.
 

Overland_stormtrooper

Caught the Bug
Would try pulling the thermostat sounds to me like ya may have gotten a bad one .. yea i know its new doesnt mean it isnt sticking .. had a tahoe a while back same issue pulled the thermostat even tho had just replaced an put in another one problem solved ..

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cozdude

Guy with a Red 2-Door
Almost sounds like there is still air in the system. I would suggest trying to burp it again.
 

jknikos

Member
Check the system for air and clean the radiator and the air con with low pressure water. I would start from there. Also i would have gone with an oem radiator as i did.

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aTX427

New member
There are a lot of good suggestions. Definitely check for air in the cooling system and remove the tune. How many miles does the engine have and what oil are you running?

Check your oil - is it low, does it look or smell burnt? Low oil levels, pre-ignition and spun bearings will cause excessive heat.

High air temperature and mountainous driving will certainly raise temperatures, but 245* isn't unheard of.

My vette would see 300* regularly in the Texas heat. I just ran very good oil that could handle it without breaking down. If everything checks out, try a Joe Gibbs turbo car oil or Mobil 1 v-twin. Both have exceptionally high temperature ratings.


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jeeeep

Hooked
lots of good recommendations, I would start with burping the cooling system.

have coolant on hand in case you need to add more.

with the front end raised up (axle on jack stands), heater off, cap off, run it for a few minutes until to temperature. if you see bubbles, you've got air in the system.

add coolant as needed. once you're satisfied all air is out of the system, turn on the heater to make sure no air is trapped in the heating core.

I've had to let mine sit overnight raised with the cap on loosely to get all the air out of the system.
 

Lmoye22

New member
Did you change your tune with the Superchips? If so try returning to stock (other than changes for gearing and tire size).

Also, I have read unfavorable things about Mishimoto radiators. If you have or can get a stock radiator, try that.

I haven't tried that yet! I have noticed the jeep shuddering at idle. I'll give it a shot! The dealer can't find anything wrong either and two other shops. I have read a lot on this and seems like jeeps run hot but all this started about a year ago.


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Lmoye22

New member
There are a lot of good suggestions. Definitely check for air in the cooling system and remove the tune. How many miles does the engine have and what oil are you running?

Check your oil - is it low, does it look or smell burnt? Low oil levels, pre-ignition and spun bearings will cause excessive heat.

High air temperature and mountainous driving will certainly raise temperatures, but 245* isn't unheard of.

My vette would see 300* regularly in the Texas heat. I just ran very good oil that could handle it without breaking down. If everything checks out, try a Joe Gibbs turbo car oil or Mobil 1 v-twin. Both have exceptionally high temperature ratings.


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Engine is at about 142k but I do have a pretty bad oil leak! I want to say it's my rear main seal. Once I get it fixed I'll try the better grade oil.


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Lmoye22

New member
Did you change your tune with the Superchips? If so try returning to stock (other than changes for gearing and tire size).

Also, I have read unfavorable things about Mishimoto radiators. If you have or can get a stock radiator, try that.

I do still have the stock. Was thinking of going back since the new one didn't really change much. I read a lot about the leaks on these Mishimoto's , any other issues? So far so good on the one I have but really thinking of switching back and returning if possible


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J

JKDream

Guest
I'm running 5.13's with 37 General grabbers.


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Are you getting the hot oil light as well? Mine has overheated a couple of times, mostly due to mud in the radiator. You have a new rad so I don't suspect that is the issue. I'd agree with others and say it's likely air in the system. Run it with the rad cap off and see if any bubbles come up.

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Lmoye22

New member
Are you getting the hot oil light as well? Mine has overheated a couple of times, mostly due to mud in the radiator. You have a new rad so I don't suspect that is the issue. I'd agree with others and say it's likely air in the system. Run it with the rad cap off and see if any bubbles come up.

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Once i installed the transmission cooler the hot oil light did go away under hard driving


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