2018 Rubicon Suddenly Overheating Uphill

[Countryswiss]

Hey Guys,
My wrangler has started to overheat when going uphill, driving around flat areas and idling I am completely fine but as soon as I go up a hill especially at highway speeds the temperature shoots up. I am running 35s and a winch in the stock steel bumper. Coolant is full and my A/C and Heat work just fine. It seems like my fan has been coming on much more often however.
I took it to a dealer and they told me the pressure test came back fine and that was all they could do... The said as far as they could tell the thermostat was opening and closing normally but they think the problem is being caused by my "aftermarket steel bumper"... I have the stock steel bumper with the end caps removed. Needless to say I wont be going back to that dealer (Denton TX)
Any advice is greatly appreciated.

Jeep idles at about 215-230 and hits 235 on flat city streets

Photo is a very slight incline at highway speeds. Ambient temp in the photo is about 70F

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[TrailScooter]

Up hills only? ?



How much do you weigh??





... you've checked the obvious; Radiator clean and clear, fan does run etc...

 

[Pinion]

It seems to be either your water pump or the thermostat.

 

[Countryswiss]

Up hills only? ?



How much do you weigh??





... you've checked the obvious; Radiator clean and clear, fan does run etc...

Yes, I have checked the fan and it runs. The radiators seems clean, I hosed it off but I havent removed it to really get in there and clean it. I am not sure if that is necessary

 

[Dyolfknip74]

Lmao. Please go back and get them to explain the mechanics behind a bumper causing a vehicle to overheat. Like, in detail. Aftermarket, OEM or not. Just the basic science of how adding a few extra lbs onto a vehicle that is designed to carry up to 5 passengers could cause such an issue. We aren't talking SpaceX tolerances here, so I would LOVE to hear this explanation.
Please record said interaction as well. Lol.

 

[Countryswiss]

Lmao. Please go back and get them to explain the mechanics behind a bumper causing a vehicle to overheat. Like, in detail. Aftermarket, OEM or not. Just the basic science of how adding a few extra lbs onto a vehicle that is designed to carry up to 5 passengers could cause such an issue. We aren't talking SpaceX tolerances here, so I would LOVE to hear this explanation.
Please record said interaction as well. Lol.

I 100% agree with you but I just couldn't be bothered trying to explain to them why they are so wrong. Everyone there was completely clueless. I decided I would rather go somewhere else / try and figure out the problem on my own

 

[Windshieldfarmer]

Is something adding drag to your Jeep - a rear caliper sticking or parking brake not fully releasing. Just a thought. Thermostats typically default to the open position when failing…

 

[mwilk012]

Do you do much off roading? Is there any mud caked to your radiator?

 

[Countryswiss]

It seems to be either your water pump or the thermostat.

Do you do much off roading? Is there any mud caked to your radiator?

I do some pretty heavy mudding, I have hosed off my radiator but havent removed it to clean it. Would a clogged radiator cause a jeep to only overheat when going uphill?

 

[Countryswiss]

Is something adding drag to your Jeep - a rear caliper sticking or parking brake not fully releasing. Just a thought. Thermostats typically default to the open position when failing…

No I do not thing anything is dragging. I think that would make a burning smell, I will double check though, good thought

 

[mwilk012]

I do some pretty heavy mudding, I have hosed off my radiator but havent removed it to clean it. Would a clogged radiator cause a jeep to only overheat when going uphill?

It takes more energy to push uphill, higher heat production in that case. As mud builds up on the radiator, it will reduce its efficiency, but until it lowers the thermal efficiency low enough that heat flux out is less than heat flux in, temps will be stable.

How quickly does temperature rise?

 

[Countryswiss]

It takes more energy to push uphill, higher heat production in that case. As mud builds up on the radiator, it will reduce its efficiency, but until it lowers the thermal efficiency low enough that heat flux out is less than heat flux in, temps will be stable.

How quickly does temperature rise?

When uphill the temperature rises very quickly to the point where I cannot even make it up some hills without it getting into the red.
I just bought some AC Coil cleaner foam from Home Depot that I will pick up tomorrow and will use it on the radiator and see how much crap I am able to get out, really hope the problem is that simple.

 

[mwilk012]

You’re going to need a power washer if a dirty radiator is the problem. Are you sure the coolant system is completely full?

 

[WagzDad]

The AC condenser is in front of the radiator. Just because it’s clear doesn’t make the radiator clean. Take the plastic cowling off over the radiator and make sure leaves or road debris is not between the 2 Impeding the air flow.

 

[Countryswiss]

You’re going to need a power washer if a dirty radiator is the problem. Are you sure the coolant system is completely full?

Yes I am confident the coolant is completely full, I am going to use a pressure washer tomorrow very carefully as to not bend the fins

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