6.4 overheating

[Emlara00]

I need some help I’ve got a 2019 Ram 2500 6.4 hemi that only overheats while towing I’ve replaced Tstat, heater core, oil cooler, radiator and flushed the coolant system. I figured it would be fixed by now but it’s not. If I watch the temps while driving the coolant temp never makes a big jump like the tstat opens up it just stays around 212 until the oil temp gets to 230 then it just starts going up and never cools back down I’ve replaced the tstat twice thinking I got a bad one out of box any help is appreciated

 

[Wild one]

I need some help I’ve got a 2019 Ram 2500 6.4 hemi that only overheats while towing I’ve replaced Tstat, heater core, oil cooler, radiator and flushed the coolant system. I figured it would be fixed by now but it’s not. If I watch the temps while driving the coolant temp never makes a big jump like the tstat opens up it just stays around 212 until the oil temp gets to 230 then it just starts going up and never cools back down I’ve replaced the tstat twice thinking I got a bad one out of box any help is appreciated

The 6.4's employ piston squirters that spray oil on the bottom of the piston top and upper rod bearing,so they run alot hotter oil temps then the 5.7's do. Changing the thermostat and everything else you've done,isn't going to have much affect on the oil temps,you're going to have to look into adding a thermostatically controlled oil cooler if you want to bring your oil temps down.

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[Emlara00]

The 6.4's employ piston squirters that spray oil on the bottom of the piston top and upper rod bearing,so they run alot hotter oil temps then the 5.7's do. Changing the thermostat and everything else you've done,isn't going to have much affect on the oil temps,you're going to have to look into adding a thermostatically controlled oil cooler if you want to bring your oil temps down.

Remote Oil Filter Mounts

Remote Oil Filter Mounts

www.improvedracing.com

High-Flow Engine & Transmission Oil Cooler Thermostat

Improved Racing's Flow Series Motor Sport (FSM) oil thermostat is a universal solution that can be used with any oil cooler on any vehicle or industrial application flowing up to 20 GPM (75.71 LPM). Trusted by professional race teams, OEM's, and military contractors. Accelerates fluid warmup...

www.improvedracing.com

Improved Racing Oil Coolers

Improved Racing Oil Coolers

www.improvedracing.com

I know these trucks typically run hotter than most and I know 230 isn’t something to be super worried about but it’s reached 260 with coolant at 250 then finally got to a spot to shut it down I’m just trying to figure out why it only happens now when towing compared to when I got the truck when it would stay below 225-230 it just seems weird to me that the coolant temp doesn’t fluctuate like it used to when the oil temp stayed normal

 

[Mojo88]

I need some help I’ve got a 2019 Ram 2500 6.4 hemi that only overheats while towing I’ve replaced Tstat, heater core, oil cooler, radiator and flushed the coolant system. I figured it would be fixed by now but it’s not. If I watch the temps while driving the coolant temp never makes a big jump like the tstat opens up it just stays around 212 until the oil temp gets to 230 then it just starts going up and never cools back down I’ve replaced the tstat twice thinking I got a bad one out of box any help is appreciated

Are your AGS opening? Is the fan working? When it heats up like that, pull over and open the hood, check the fan and AGS operation.

For starters, I'd install a 180* stat and remove some (in the center) of the AGS shutters. This might fix you up, and cheap to do.

You could get into the tune and modify the PWM fan settings to come on at lower temp, and this would automatically open the AGS at lower temps too. If you combine that with a 180* stat, that 'should' solve your issue. But you'd need to get into the tune, which costs a few bucks.......

Bottom line, these engines are designed to run hotter than most of us are used to. It doesn't take much to really get the temps up there.

 

[dieselscout80]

The 6.4 thermostat is not a regular thermostat that’s replaceable it’s built into the thermostat housing and has a built in heating element.

I don’t think there are any replacements with a lower temperature rating.

Mine was not closing causing code for irrational temperature error code.

I cut the old one apart see picture.

 

[dieselscout80]

18’ Power Wagon Oil temps HOT

I just bought a new to me 2018 2500 power wagon with the 6.4 hemi. I have noticed when going up the cajon pass completely empty and not towing anything that my engine oil temps get to 250-260! I immediately pulled over and checked it out and everything looks fine. Truck never went into limp mode...

www.ramforumz.com

 

[Wild one]

The 6.4 thermostat is not a regular thermostat that’s replaceable it’s built into the thermostat housing and has a built in heating element.

I don’t think there are any replacements with a lower temperature rating.

Mine was not closing causing code for irrational temperature error code.

I cut the old one apart see picture.

If you want to spend money tuning the truck,you can get rid of that style thermostat and use a normal style thermostat and thermostat housing like the 6.4 cars use,and then use HP tuners to delete the thermostat rational code.That opens up your thermostat options

 

[dieselscout80]

The 6.4 thermostat is not a regular thermostat that’s replaceable it’s built into the thermostat housing and has a built in heating element.

I don’t think there are any replacements with a lower temperature rating.

Mine was not closing causing code for irrational temperature error code.

I cut the old one apart see picture.

The heating element allows the thermostat to heat up and open earlier.

I hooked the old element up to a 12 volt power supply and it got hot quickly.

 

[Zoe Saldana]

I know these trucks typically run hotter than most and I know 230 isn’t something to be super worried about but it’s reached 260 with coolant at 250 then finally got to a spot to shut it down I’m just trying to figure out why it only happens now when towing compared to when I got the truck when it would stay below 225-230 it just seems weird to me that the coolant temp doesn’t fluctuate like it used to when the oil temp stayed normal

I think the Thermostat should opens at about 200 or 210 and hold there.

Did you put one with that range?

I have a 2016 6.4l with 100k and the coolant temp is rock steady a little left of center.

When the temps rise, did you turn on the heat to high to see if that does anything?

 

[crash68]

2019 Ram 2500 6.4 hemi that only overheats while towing

Describe the trailer your towing, how much it weighs and how fast are you trying to travel while towing.

 

[pgoodwin79]

Probably a stupid question..are you remembering to turn the tow mode on when towing? If not the shift points will be different and could cause overheating when towing a load

 

[Emlara00]

Describe the trailer your towing, how much it weighs and how fast are you trying to travel while towing.

What I tow most is my pontoon total weight boat and trailer is a little less than 4,000 and within 10 miles at 55 mph it gets oil temp to 255 coolant around 240

 

[crash68]

What I tow most is my pontoon total weight boat and trailer is a little less than 4,000 and within 10 miles at 55 mph it gets oil temp to 255 coolant around 240

That does seem a bit warm but pontoons are like towing a giant parachute. Wind load is way worse than weight.
What @Wild one mentioned about these engines using piston squirters explains in part why the oil can run warm, do those temps climb if keep towing at that speed? You might just be getting to the thermal soak of the engine. Too low of RPMs for the load can cause pinging which pulls timing which can cause the engine to run warmer. Could be a fuel quality issue or not enough gear while towing.Are you using Tow/Haul? and don't try to goose the shifts where you speed up, then let off the throttle force the up shift.
Just rambling out some ideas

 

[Emlara00]

That does seem a bit warm but pontoons are like towing a giant parachute. Wind load is way worse than weight.
What @Wild one mentioned about these engines using piston squirters explains in part why the oil can run warm, do those temps climb if keep towing at that speed? You might just be getting to the thermal soak of the engine. Too low of RPMs for the load can cause pinging which pulls timing which can cause the engine to run warmer. Could be a fuel quality issue or not enough gear while towing.Are you using Tow/Haul? and don't try to goose the shifts where you speed up, then let off the throttle force the up shift.
Just rambling out some ideas

The highest the oil temp has got was 265 and at that point it was to high for comfort so I shut it down I always use tow haul and I try to keep shifts smooth

 

[Burla]

Try water wetter.

Try RMI25 and then water wetter after 500 miles, see if rmi flushes casting sand you are in casting sand years even though most everything replaced.

Delete any shutters.

a few ideas there, you are on the edge with those temps, idle down like a diesel protect the heads.

 

[Wild one]

The highest the oil temp has got was 265 and at that point it was to high for comfort so I shut it down I always use tow haul and I try to keep shifts smooth

Hopefully you changed oil shortly after that temp.
Looks like the only thing you didn't change was the water pump if i'm reading your first post right,might be something you want to check,as maybe the pump impeller is slipping on the shaft when it gets hot.
Another thing to check when you lift the intake pull the water pump to check it over,is to pull the egr cooler off and clean or replace it

 

[BigTerry66]

I know these trucks typically run hotter than most and I know 230 isn’t something to be super worried about but it’s reached 260 with coolant at 250 then finally got to a spot to shut it down I’m just trying to figure out why it only happens now when towing compared to when I got the truck when it would stay below 225-230 it just seems weird to me that the coolant temp doesn’t fluctuate like it used to when the oil temp stayed normal

Get a couple can of liquid cool pour into the radiator.. then get a bottle of Luca high mileage oil additive... it work great for diesel log truck...

 

[Dusty]

I need some help I’ve got a 2019 Ram 2500 6.4 hemi that only overheats while towing I’ve replaced Tstat, heater core, oil cooler, radiator and flushed the coolant system. I figured it would be fixed by now but it’s not. If I watch the temps while driving the coolant temp never makes a big jump like the tstat opens up it just stays around 212 until the oil temp gets to 230 then it just starts going up and never cools back down I’ve replaced the tstat twice thinking I got a bad one out of box any help is appreciated

Bad aftermarket thermostats seem to be the rage nowadays, but some background would be helpful.

Is this a vehicle you've had for awhile and this is a recent issue, or is the vehicle relatively new to you?

Have you read any stored codes, and if so what are they?

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 150779 miles.