Running Hot

[stumblinhorse]

Would you point me in the direction you purchased the radiator & hoses for our 392?

I did not do the 392. I tried with my JK and spent a lot of money and time to find out it doesn’t help. I also found that the aftermarket radiators were not as reliable as an OEM. It is a theme with the modern engine. As @dan392 says having the fan run early is the only thing that truly impacts the temp.

The engine is designed to run at around 225° Coolant and ~250° oil. If you are uncomfortable with those numbers, my advice is have the fan lower the temps. That advice is worth what you paid for it…

 

[Casper]

I got my fan controller from rpmextreme.com. I've invited the owner to reply to this thread, but he's on the grumpy side, so we'll see...

The problem on overwriting the radiator on a modern Jeep (and most other vehicles) is that they are PWM controlled motors. They have a built in controller that needs a device that "talks" its language (interface). Replacing the fan with an old style voltage controlled one will have the ECM (computer) throw errors and Christmas tree the dash lights.

That's where a solution such as the RPMEX comes into play. It tricks the computer while it (RPMEX) controls the fan speed. However, it's not for the faint at heart since one needs to tap into the ECM harness and also tap the fan PWM wire. Not rocket science, but something that a dealer could discover. Not sure how this would impact the warranty. My JK is way past that, but for a new(er) 392 that would be a major consideration.

 

[stumblinhorse]

I got my fan controller from rpmextreme.com. I've invited the owner to reply to this thread, but he's on the grumpy side, so we'll see...

The problem on overwriting the radiator on a modern Jeep (and most other vehicles) is that they are PWM controlled motors. They have a built in controller that needs a device that "talks" its language (interface). Replacing the fan with an old style voltage controlled one will have the ECM (computer) throw errors and Christmas tree the dash lights.

That's where a solution such as the RPMEX comes into play. It tricks the computer while it (RPMEX) controls the fan speed. However, it's not for the faint at heart since one needs to tap into the ECM harness and also tap the fan PWM wire. Not rocket science, but something that a dealer could discover. Not sure how this would impact the warranty. My JK is way past that, but for a new(er) 392 that would be a major consideration.

we used HP tuner software to do it on JKs. Just need to unlock the ECM.

 

[Casper]

we used HP tuner software to do it on JKs. Just need to unlock the ECM.

Learning a new thing everyday. Do they have it available for the 392?

 

[Casper]

I got my fan controller from rpmextreme.com. I've invited the owner to reply to this thread, but he's on the grumpy side, so we'll see...

OK, he replied in private - he seems to be grumpy and shy : no 392 support at this time. Seems like HP Tuners is the only option for now, although not sure if all 392 years are covered.

 

[stumblinhorse]

Learning a new thing everyday. Do they have it available for the 392?

@LTZ470 also said that the Diablo folks are gonna have something specifically for the 392 Fan.

 

[Ted392]

Good information in this thread. Thanks.

 

[EBYCREEK]

Coolant or oil temp running hot?

Coolant runs as hot as 235 then the fan turns on and cools it down to around 200. I wouldn't really care about the coolant temperature as I know this is normal. The problem is it overheats my power steering pump. I'm on my 3rd power steering pump at 8,000 miles. I've added the Apex power steering cooler but that didn't seen to help. I continue to get the power steering hot light usually on a slow climb at about 12,000 feet. I'm running 37x12.50 KM3 Tires air downed to 12 PSI. I added a fan in front of my power steering pump and this seems to have fixed it for now. I'm sure if I could bring my max coolant temperature down 20 degrees this would help.

 

[gr1p]

Gentlemen, high temps for oil and coolant on these engines are completely normal for modern v8s and match what I saw on my LT1 genV swapped jk as well. Notice that the gauges in off-road pages show normal color with coolant topping 230 and oil over 250.

 

[ameldorf]

@LTZ470 also said that the Diablo folks are gonna have something specifically for the 392 Fan.

You can already control the fan with DS.

I use it with a 180 thermostat set at 185.

 

[Casper]

You can already control the fan with DS.

I use it with a 180 thermostat set at 185.

Which product is that? Do you have a link by any chance? Is it for the 392?

 

[ameldorf]

I use a Diablosport Intune w/unlocked PCM and a 180 tstat for a 392. It has a custom tune but you can control the fan temps with the Intune.

 

[Casper]

Would the unlocked PCM void the factory warranty? Anyone with first hand experience?

 

[ameldorf]

Ma

Would the unlocked PCM void the factory warranty? Anyone with first hand experience?

Magnuson moss warranty act says the manufacturer/dealer has to prove the mod caused the damage. There’s a ton of grey area particularly if you have no mechanical knowledge or understanding of how the mod could impact the vehicle, along with the funds to fight a claim. Best bet is to either have a good relationship with a dealer if modding, do the work yourself and dgaf about warranty, or don’t mod your shit.

 

[guruman]

Would the unlocked PCM void the factory warranty? Anyone with first hand experience?

If you tried to make a claim for anything in the drivetrain, they will most certainly know you've modded the PCM, and would deny any claim, for the driveline anyway, based on the fact that it was engineered to run at the factory parameters. You could take them to court to enforce the warranty, but I do not see how you'd win that argument.

The second they hook up the computer, they will know, and even a friendly dealer can't make Jeep honor the warranty, and I doubt you'd find one friendly enough to lie to Jeep about it.

 

[Mandrake]

well, I won't worry about 235 oil temp on a hot day running 70 mph @2100 rpm. The oil temp indicator was still green, coolant temp was only 206. As long as a good amount of air is coming into the radiator, coolant temp stays relatively low. Not 197, but I can live with 206.
Challenger does better with temps.
I guess this 0w-40 can handle it.
I was just surprised at 235 for oil temps but after reading this thread, anything below 250 degrees Fahrenheit, seems to be okay.

 

[Bobo57]

well, I won't worry about 235 oil temp on a hot day running 70 mph @2100 rpm. The oil temp indicator was still green, coolant temp was only 206. As long as a good amount of air is coming into the radiator, coolant stays low. Not 197, but I can live with 206.
Challenger does better with temps.
I guess this 0w-40 can handle it.
I was just surprised at 235 for oil temps but after reading this thread, anything below 250 degrees Fahrenheit, seems to be okay.

250 seems hot to me also, but I usually see that temp when climbing a hill. Just gonna change oil more often.

 

[stumblinhorse]

My advice on oil temps is pay attention to anything 260° plus. I have seen 250s many times in both my hemis. No issues so far. And the 5.7 “requires” 5w-20! I refuse to run that, so I run 5w-30 PUP.

 

[Fast-n-Furious]

well, I won't worry about 235 oil temp on a hot day running 70 mph @2100 rpm. The oil temp indicator was still green, coolant temp was only 206. As long as a good amount of air is coming into the radiator, coolant temp stays relatively low. Not 197, but I can live with 206.
Challenger does better with temps.
I guess this 0w-40 can handle it.
I was just surprised at 235 for oil temps but after reading this thread, anything below 250 degrees Fahrenheit, seems to be okay.

I see 240+ frequently daily driving. Also the temp is a higher in off-road+ mode based on my observation. You can verify.