Novak Conversions Jeep Wrangler JK radiators

Overheating at highway speeds

Overheating at highway speeds usually indicates airflow is being blocked or diverted. Airflow can be blocked or diverted by anything mounted in front of the radiator such as winches, lights, grill inserts or stingers.

Airflow can be blocked from exiting the engine compartment by aftermarket splash shields, incorrectly installed splash shields, skid plates or other items.

Air flow through the engine compartment might be disrupted by removing or incorrectly installing shrouds. Damaged or clogged fins on the A/C condenser or transmission cooler will block airflow to the radiator.

What happened when your Jeep overheated? Was it boiling over? Or just indicating high temps? Was coolant lost just from the overflow bottle? Or was coolant lost in the radiator as well? If it was just the overflow bottle, it could be the bottle was over serviced and the system was seeking its own level.
 
GP Noir said:
Overheating at highway speeds usually indicates airflow is being blocked or diverted. Airflow can be blocked or diverted by anything mounted in front of the radiator such as winches, lights, grill inserts or stingers.

Airflow can be blocked from exiting the engine compartment by aftermarket splash shields, incorrectly installed splash shields, skid plates or other items.

Air flow through the engine compartment might be disrupted by removing or incorrectly installing shrouds. Damaged or clogged fins on the A/C condenser or transmission cooler will block airflow to the radiator.

What happened when your Jeep overheated? Was it boiling over? Or just indicating high temps? Was coolant lost just from the overflow bottle? Or was coolant lost in the radiator as well? If it was just the overflow bottle, it could be the bottle was over serviced and the system was seeking its own level.
Click to expand...
the coolant was boiling over due to the fans not kicking on when they were intended too it has not boiled over since the first time
 
  • Like
Reactions: mrjp
Anybodyhome said:
1 of 2 probable culprits: Temp sensor and thermostat.
1. T-stat. There are a bunch of cheaper versions out there in the $25-40 range, but the MOPAR replacement, with housing, is around $53.
2. Temp sensor: Again, cheaper versions in the $16-24 range, but the MOPAR replacement will run you about $38.

I have to believe it's one of these unless the fan somehow got screwed up when you replaced it. Check the fuses and wiring on the new fan. Has it ever run at any speed except high? If it runs at both low & hi speeds, the fan is not the issue.

And one more thing- if the t-stat was stuck in the open position, you'd see the temp gauge all over the map, from low to high, with the higher temps occurring when the Jeep is standing still.
Click to expand...
What temp does the low kick in at? I thought it doesn’t kick on at all until 226.
 
  • Like
Reactions: mrjp
I have 2015 and it is running hot at highway speed 245. I replaced the water pump, radiator, thermostat, and coolant sensor. I have nothing blocking the radiator and have checked for air in the coolant system. The fan is also working the way it should. I have taken it to 2 different mechanics and they say everything is working correctly.

It is starting be a bit sluggish and mt gas mileage, any thoughts?
 
Stan said:
I have 2015 and it is running hot at highway speed 245. I replaced the water pump, radiator, thermostat, and coolant sensor. I have nothing blocking the radiator and have checked for air in the coolant system. The fan is also working the way it should. I have taken it to 2 different mechanics and they say everything is working correctly.

It is starting be a bit sluggish and mt gas mileage, any thoughts?
Click to expand...

Is your Jeep a automatic?
 
we have a 2014 3.6--Check oil cooler! Coolant will run down the back of the engine, Jeep Dealer replaced half the cooling system before we figured it out by googling and asking around
 
  • Like
Reactions: BigAL07
mulletmanjk_noah said:
i drive a 2015 jeep wrangler sport with the 3.6 v6. i had my radiator, radiator fan, thermostat, water pump, and temperature sensor replaced. the jeep reads 226 around town with the radiator fan constantly on high. how ever at highway speeds i cant exceed 70 to 75 mph without my temps shooting to 230+ any idea what this could be? the jeep has over heated one time which is why i replaced all of the cooling system,
Click to expand...
The radiator is plugged up on your vehicle. A plugged radiator will allow the engine to operate normally in town and on surface streets, but when driving at highway speeds with the engine running at a higher speed all the time, then the radiator cannot cycle the fluid fast enough and causes the engine to overheat. You can check out Mopar Genuine Parts for high quality replacements parts.
 
  • Like
Reactions: BigAL07
GP Noir said:
Overheating at highway speeds usually indicates airflow is being blocked or diverted. Airflow can be blocked or diverted by anything mounted in front of the radiator such as winches, lights, grill inserts or stingers.

Airflow can be blocked from exiting the engine compartment by aftermarket splash shields, incorrectly installed splash shields, skid plates or other items.

Air flow through the engine compartment might be disrupted by removing or incorrectly installing shrouds. Damaged or clogged fins on the A/C condenser or transmission cooler will block airflow to the radiator.

What happened when your Jeep overheated? Was it boiling over? Or just indicating high temps? Was coolant lost just from the overflow bottle? Or was coolant lost in the radiator as well? If it was just the overflow bottle, it could be the bottle was over serviced and the system was seeking its own level.
Click to expand...
I have a 2016 jeep wrangler, just picked it up from shop from over heating. They replaced the radiator, water pump and the thermostat 3 times . Only made it 5 miles and it over heated at hwy speed again. It’s been pressure tested and passing beautifully. It only dose it at hwy speeds . I don’t know what else they can replace on it. I’m ready to cry over this because I’m making a payment on a vehicle that is setting in a shop more then I have it at home. Please help!
 
Tiffsjeep said:
I have a 2016 jeep wrangler, just picked it up from shop from over heating. They replaced the radiator, water pump and the thermostat 3 times . Only made it 5 miles and it over heated at hwy speed again. It’s been pressure tested and passing beautifully. It only dose it at hwy speeds . I don’t know what else they can replace on it. I’m ready to cry over this because I’m making a payment on a vehicle that is setting in a shop more then I have it at home. Please help!
Click to expand...


They might not have bled all the air out of the cooling system.
 
  • Like
Reactions: BigAL07
Does the temp stay high, or does it drop quickly? If it drops quickly it may be what @BLACKJKU stated about air in the system. How are you monitoring the temp, via the dash gauge or the DIC readout where you can see the actual temperature?
 
  • Like
Reactions: BigAL07
mulletmanjk_noah said:
i drive a 2015 jeep wrangler sport with the 3.6 v6. i had my radiator, radiator fan, thermostat, water pump, and temperature sensor replaced. the jeep reads 226 around town with the radiator fan constantly on high. how ever at highway speeds i cant exceed 70 to 75 mph without my temps shooting to 230+ any idea what this could be? the jeep has over heated one time which is why i replaced all of the cooling system,
Click to expand...
Hey there did you find out the problem cause I am having the same issue I have changed everything and it's still running hot
 
Tiffsjeep said:
I have a 2016 jeep wrangler, just picked it up from shop from over heating. They replaced the radiator, water pump and the thermostat 3 times . Only made it 5 miles and it over heated at hwy speed again. It’s been pressure tested and passing beautifully. It only dose it at hwy speeds . I don’t know what else they can replace on it. I’m ready to cry over this because I’m making a payment on a vehicle that is setting in a shop more then I have it at home. Please help!
Click to expand...
I had the same issue. I've been battling overheating issues for over a year with my 2012 jku rubicon. Especially in summer in Phoenix and going uphill it was running 240+ and i couldn't drive faster than 60 mph. First i replaced the radiator. Then the thermostat was replaced. No change so i kept going. Replaced the waterpump and even the transmission oil cooler. Took the winch off. Nothing helped. Since it was only happening at higher speeds and it was fine at lower speeds i didn't suspect the thermostat. Especially since it was replaced.
I had the engine and cooling system tested and the mechanics said everything was fine. So as a last resort i decided to remove the internal part of the thermostat. It's really simple to do and you'll be able to see if the thermostat is the issue. After this the car was running normal Temps. Apparently the new thermostat that was installed was faulty out of the box. I just threw a new duralast (motorad) thermostat in there since i couldn't get my hands on a mopar one. And voila. Problem solved.
These thermostats are crap and usually the problem. Suggest taking it out and testing it that way.
I hope this helps you and other people.
 
Novak Conversions Jeep Wrangler JK radiators
Top Bottom