Gen2 overheating when driving slow hills

[MummifiedCircuitry]

My Gen2 is still overheating when driving slowly up hills. It won't overheat on the highways or going uphill at highway speeds, just low speeds (0-10mph). It can sit stationary for any amount of time and not overheat either, only on slow incline. I've replaced basically every cooling component except the water pump. New 170C thermostat, new CSF all metal 2-row radiator, new 13psi radiator cap, new upper and lower radiator hoses, dual 12" 1730cfm puller fans, new coolant temp sensor, new temp sender, used flush and clean solution, all fresh coolant and bled the system multiple times. Any ideas? I feel like it's not the water pump or it'd overheat when sitting still.

 

[Salonika]

What is telling you that it is overheating? The instrument panel gauge? Do you have access to a scan tool that can report the actual temp to you? Maybe your gauge is malfunctioning?

 

[TheMole]

Did you reinstall the fan shroud?

 

[MummifiedCircuitry]

What is telling you that it is overheating? The instrument panel gauge? Do you have access to a scan tool that can report the actual temp to you? Maybe your gauge is malfunctioning?

The temp gauge is showing hot and the radiator/overflow will start boiling.

 

[MummifiedCircuitry]

Did you reinstall the fan shroud?

I did not reinstall the shroud after switching to electric fans, do you think it would make that much of a difference?

 

[TheMole]

I did not reinstall the shroud after switching to electric fans, do you think it would make that much of a difference?

Ah forgot you have electric fans so it sits right up against the radiator. Might be worth trying reinstall the fan shroud since its only 4 bolts and much easier without the oem fan in the way. If it still overheats, try going back to the oem fan.

 

[MummifiedCircuitry]

Ah forgot you have electric fans so it sits right up against the radiator. Might be worth trying reinstall the fan shroud since its only 4 bolts and much easier without the oem fan in the way. If it still overheats, try going back to the oem fan.

It overheated with the OEM fan before I installed the electric fans. I don't know how much air the stock clutch fan moves, but I'm pretty sure dual 1730cfm fans pull more. I will try installing the fan shroud though, I'm almost out of ideas.

 

[jeep-N-montero]

Post a picture of this electric fan setup and you can receive feedback on how efficient or inefficient it may be, I have been doing fan swaps on numerous rigs for years and have seen some pretty hacked setups that I fixed the correct way.

 

[MummifiedCircuitry]

Post a picture of this electric fan setup and you can receive feedback on how efficient or inefficient it may be, I have been doing fan swaps on numerous rigs for years and have seen some pretty hacked setups that I fixed the correct way.

Each fan is wired to it's own fused power. 2x 12" covered more area than a single 16" or 20" like some people do. I'm open to suggestions if you have any.

 

[nckwltn]

Some ideas to think about.

Do you have some multi meter that can measure current? Perhaps the fans aren't getting enough power, and aren't turning as fast as they should?

Are the fans pulling air through the radiator or pushing into the radiator?

Can you override the temp activation and force them on regardless of engine temp? Perhaps they aren't coming on soon enough?

Do you happen to have anything in front of the radiator that might be blocking air flow? At speed air might be getting forced past obstructions.

What RPMs are you running at the low speeds?

Overheat at the same speeds on flat ground? Up hill puts more load on the engine. Up hill and 4k+ rpm causes my temps to go up.

At 10mph, how about going to low range and see if a different rpm but same speed makes a difference. More rpm means the water pump is moving more coolant.

 

[MummifiedCircuitry]

I do have a multimeter, but I haven't measured current yet. The fans are quite loud and I can put my hand behind them and a ton of air is being moved. They're wired to 50A toggles which I flip on when I start up and leave on, so not temp controlled. Nothing is in front of the radiator except the AC condenser. I don't have a front bumper on either, so even more air is getting through. The RPM's at low speeds are minimal, probably 1500-2000, I never really rev the engine past 3500-4k at any point. I'll take it out for a drive tomorrow and try some low speed on flat land and low range uphill situations and see how it performs. Thank you for the suggestions.

 

[nckwltn]

Did you have this overheating before the new radiator

Another crazy thought is that perhaps the radiator has too much flow capacity. So the coolant is getting through too quickly and not exchanging heat....

At speed it isn't a problem because the additional airflow through the radiator can exchange out the heat with the coolant flow rate.

I'm not even sure if that is actually something that can exist, just a thought experiment.

 

[MummifiedCircuitry]

It did overheat at slow speeds going uphill before I replaced all of the parts that I listed. I've been trying to chase it down, but apparently didn't get it yet. Interesting idea about too much flow, I don't think it's the issue in this case though. With the radiator cap off, the coolant can be seen passing the mouth of the radiator, but by no means is it rushing through more than normal. I really can't think of any other causes, aside from some mystery blockage within the engine itself. The previous owner ran rusty water in it for who knows how long, but as I said, I've replaced almost all cooling components and flushed/cleaned the system multiple times, the coolant is clean with no debris now.

 

[JamesW]

Are you sure the fans are sucking and not blowing? I've seen it happen to people a few times that they wire them in backwards,and it is fine at a stop, and fine at speed, but it will get warm after a little bit of driving around looking for a parking space or in slow rolling traffic.

 

[Salonika]

When you experience the overheating, have you tried blasting the cabin heat to see if that does anything to lower temp?