Overheating at highway speeds

noahs2015jk

noahs2015jk

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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 770 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. I have also noticed that the fan is extremely loud and someone told me it may be mounted backwards. is that possible? if so how do i tell.
 
There is a problem with some of the JK's with a auto trans that the LU converter was causing a overheating issue.
 
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Another thing if you didn't get all the air out when you had your cooling system opened up it will cause a overheat. Jack the front of the Jeep up and remove the radiator cap then let it sit for a few minutes then check the coolant level.
 
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BLACKJKU said:
Another thing if you didn't get all the air out when you had your cooling system opened up it will cause a overheat. Jack the front of the Jeep up and remove the radiator cap then let it sit for a few minutes then check the coolant level.
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Getting the air of these is a huge pain in the rear. The front needs to be higher than the rear, hill or jack. Open the rad cap on a cool engine and start it up, put the heater on high and keep it topped off. It may take awhile, you should be good if really really hot air is blowing out of the vents.

The overflow tank isn't the place to fill the radiator fyi
 
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noahs2015jk 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 770 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. I have also noticed that the fan is extremely loud and someone told me it may be mounted backwards. is that possible? if so how do i tell.
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Having similar problems. Currently on a 24 hour road trip which is the worst part.. the further we drive, the slower the Jeep is getting. I also have a 2015 2D sport. Can barely get this thing to 70 anymore. Did you find a solution?
 
I would make sure that you haven't mixed coolant types. For some reason, the auto industry thought it would be a good idea to update the coolant type with something that can turn into gel if mixed with the old type. for this reason I only get the universal type it can mix with either. I think a flush can fix this, but I would take it in and have them check the coolant numbers.
 
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noahs2015jk 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 770 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. I have also noticed that the fan is extremely loud and someone told me it may be mounted backwards. is that possible? if so how do i tell.
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Did you ever figure this out? I am hoaxing the exact same issue with my 2015 but it didn’t start until after having my oil cooler done
 
I am also having the same issue, have installed a high cap radiator, and everything else all new I mean everything has been upgraded or replaced, same issue. Heavy head winds or high speeds and engine over heats can get it to 250 easy especially up hill.
 
kevinhomuth said:
I am also having the same issue, have installed a high cap radiator, and everything else all new I mean everything has been upgraded or replaced, same issue. Heavy head winds or high speeds and engine over heats can get it to 250 easy especially up hill.
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Are you sure you have all the air burped out by raising the front up with cap off and idling?

Read Post No 49 in this link. https://wranglerjkforum.net/threads...nging-the-thermostat.30145/page-3#post-458453
 
Yes, and I have a snap on pressure testing kit with gauge so I can watch the pressure rise and transfer coolant into over flow and back again to insure there is no space in system. I also have a co2 test kit that I used to check for cracked head or blown head gasket. As the coolant started expanding the dye in top cell stayed blue as the coolant filled bottom cell and transferred into overflow. No bubbles nothing.
 
kevinhomuth said:
Yes, and I have a snap on pressure testing kit with gauge so I can watch the pressure rise and transfer coolant into over flow and back again to insure there is no space in system. I also have a co2 test kit that I used to check for cracked head or blown head gasket. As the coolant started expanding the dye in top cell stayed blue as the coolant filled bottom cell and transferred into overflow. No bubbles nothing.
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Did you read the link about the cooling fan?
 
Yes I did, I have already replaced cooling fan even though I tested it in a few ways and couldn’t find an issue. I have a laser that measures rpm and I was able to witness the rpm changes as the temp raised. I have stickers that stick to a blade and I can shoot the laser from underneath. I blocked off airflow to radiator with cardboard and was able to monitor the fan continue to ramp up. I don’t remember what rpm’s I was getting because when I went online after the test I could not find any info about rpm ranges that were normal at various temps so I just went and bought the Dorman 621-601 which should be equal to or better than OEM from what I have read and no change. Fan seems to come on at about 221-223 sensor is knew as well.
 
Also no oil in coolant and no water in oil. I should have mentioned early on that this issue started after I got the Jeep back from body shop. Light damage from a car that clipped the front of me running a red light. They had replaced radiator with an Auto Zone brand radiator. Jeep started over heating as soon as I took it out for the first long ride on highway. I thought it was the cheap after market radiator so I replaced it with the high cap Mishimoto MMRAD-WRA-07V2 but no change at all, and then went through everything else. I also installed a stock bumper with no winch thinking there was air getting diverted over radiator but no change. I have had it at a shop in Indio and they could not figure it out turns out I know more than they do. They did say no codes or issues popped up for them when they plugged into it.
 
BLACKJKU said:
Are you sure you have all the air burped out by raising the front up with cap off and idling?

Read Post No 49 in this link. https://wranglerjkforum.net/threads...nging-the-thermostat.30145/page-3#post-458453
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Please done let this freak you out, but simply expand where you are looking for a solution.

I wrestled a problem similar to this very recently. Mine was a combination of stuck brake caliper (diagnosed by hot wheel) and air in the coolant system. While these things are capable, they aren't powerhouses. The increased load by a bind in your drivetrain somewhere coupled with a cooling issue is sure to cause issues.

Also, just out of curiosity, did you test your new thermostat before you installed? I've read quite a few posts about faulty aftermarket thermostats.

Good luck brother and have a good one!
 
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Yes I put it into a pot with the old one and they both opened at the same time I think it was like 198 or something like that I had a turkey thermometer in the pot so not sure how accurate it was but I did confirm I was replacing thermostat for nothing. I’m checking the cats tomorrow to see if they might be plugged. They are close to the engine and it maybe sending hot back pressure back to engine at high speeds. I don’t notice a performance issue so this is probably not going to go anywhere. Then after that I’m going to check flow from water pump, not sure how I am going to set it up but I’m sure I’ll figure something out.
 
Got the same problem with my 2015 wrangler.No leaks no coolant in oil no smoke from back fan running it is loud. When started it up the temperature goes up quickly and when running at high rpm’s it will climb up to 240. Had thermostat changed several months ago everything was fine until couple weeks ago. I took a thermal heat gun and check everything under the hood when the gages were showing 230 and Nothing under the hood was the hot upper hose was 180 lower 170 thermostat was 160 temperature sensor was 170 heads 180.
 
Randall Manley said:
Got the same problem with my 2015 wrangler.No leaks no coolant in oil no smoke from back fan running it is loud. When started it up the temperature goes up quickly and when running at high rpm’s it will climb up to 240. Had thermostat changed several months ago everything was fine until couple weeks ago. I took a thermal heat gun and check everything under the hood when the gages were showing 230 and Nothing under the hood was the hot upper hose was 180 lower 170 thermostat was 160 temperature sensor was 170 heads 180.
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Sounds like your temp sensor is bad, there have been a couple Members who have had to replace them.
 
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