5.7 overheating when towing in mountains

[ramffml]

Just to be clear, I'm not trying to argue or anything. Just making some statements to consider.
The F-150 did give them an overheat message in the above video. The thing to consider when comparing the OP to this video.
- The F-150 is pulling the maximum weight trailer around 10,000, foot to the floor, and only going 18 mph. I didn't see them mention the outside temp but would expect it was hotter outside.
- The OP was only pulling 4,000 lbs. which is less than half, at the most, of the max towing capacity. They did not specify the speed or if they were running foot to the floor. I would suspect if the F-150 was only towing 4,000 lbs., running even twice the speed at 36 mph, and the outside temp was cooler the outcome would have been different.
Again, I don't want to sound like I'm arguing or disagreeing.......just adding in the way I look at it. Mainly there are a lot of different variables going on here that could affect the outcome.

All I'm saying, is yes there are many reports of hemis getting too hot. As I said I saw this on my brand new truck pulling 5000 pounds. There is nothing "wrong" with the cooling system, as in, their truck is working as designed, and getting back to the initial point, a 180 Tstat can definitely help with this.

 

[Johnny Paycheck]

OP has a few problems. 11,000+ feet of elevation doesn’t help with cooling (less dense air) or engine power losses (engine runs rich with less oxygen available, computer has to cut back on fuel, so now it’s running lean and heating up) and that load is trying to go straight back down hill where gravity wants it to go. That’s a lot of drivetrain stress.

If I was a betting guy, that coolant mix is 50-50. I’d go straight 100% coolant to fight off the lower air pressure and lower boiling temp that high elevations create.

That’s the easy fix short of getting a bigger truck that won’t have to work the engine as hard.

 

[Wild one]

OP has a few problems. 11,000+ feet of elevation doesn’t help with cooling (less dense air) or engine power losses (engine runs rich with less oxygen available, computer has to cut back on fuel, so now it’s running lean and heating up) and that load is trying to go straight back down hill where gravity wants it to go. That’s a lot of drivetrain stress.

If I was a betting guy, that coolant mix is 50-50. I’d go straight 100% coolant to fight off the lower air pressure and lower boiling temp that high elevations create.

That’s the easy fix short of getting a bigger truck that won’t have to work the engine as hard.

Straight coolant is very poor at pulling heat out of metal.If anything you want to thin it down slightly from 50/50

 

[xtryfun]

I apologize in advance for the long post but I really need some help and want to provide the necessary info.
I have a 2021 Warlock with 5.7 Hemi and towing package. It has 38,000 miles on it and I’m the 2nd owner. I bought the truck specifically to tow a small travel trailer of less than 4000 lbs. it is a single axle trailer and is 20 ft long and I have verified the loaded weight on a Cat scale. I use a weight distribution hitch and all is set up correctly by a competent shop.
Trailer pulls fine and truck runs great on relatively level or short grades but in Colorado, things are not flat. The problem is on long and steeper grades the engine overheats. First experience was coming east up I-70 to the Eisenhower/Johnson tunnels. Ambient temp was 65 degrees and the engine hot warning alert happened less than 1/2 mile from the summit. I immediately slowed to about 40 mph and entered the tunnel and down grade where I let off the gas and began coasting down hill. Warnings went off and temps cooled immediately. I had been surprised by the warning and didn’t check the diagnostic screens for actual temperatures.
I took the truck to a reputable shop. They looked things over and determined the fan clutch was bad and also recommended a new water pump, thermostat and radiator cap. They also drained and flushed the cooling system.
Two weeks later, I hook up the trailer and pulled up La Veta pass. Not a terribly steep grade but a very long climb. Water temp held steady but climbed slowly to about 230 over about 10 miles. Engine temp about 240 and tranny at 193. The last couple miles of the pass are steeper and suddenly the water got to 250 and height temp warning alerted. Pulled over and let idle. Temp quickly dropped back to about 225 as air temp was only 60.
I took truck back to the shop and they were able to replicate the heating under load on a Dino. They have performed a myriad of other tests and say the heads, head gaskets and block all test fine.
What can I do next to resolve this overheating issue. I know it isn’t normal and I see others relating similar experiences on various forums but I haven’t seen anyone really give a definitive solution.
I’m all ears. Thanks in advance!

Sounds like you’ve done all the basics right—cooling system flushed, fan clutch replaced, water pump, thermostat, radiator cap—all the usual suspects. What you’re describing is unfortunately pretty common with the 5.7 Hemi when towing in mountainous terrain. A few things to consider next:

1. Transmission and engine cooling upgrades – Even with the factory towing package, the stock radiator and AC condenser might be under-spec for long climbs at low speeds. Some owners add a high-capacity radiator or an auxiliary transmission cooler to help keep temps in check.
2. Fan operation under load – Make sure the new fan clutch is actually fully engaging under high load. Sometimes aftermarket replacements or even OEM units can have slightly different engagement curves.
3. Engine load management – On long grades, keeping speeds moderate, using a lower gear, and feathering the throttle can make a huge difference. Even small adjustments in how you approach the grade help heat management.
4. Airflow – Check for any obstruction in front of the radiator or AC condenser, like a bug screen, brush, or aftermarket brush guards. Restricted airflow can raise temps significantly under load.
5. Aftermarket performance options – Some Hemi owners install a more aggressive electric fan setup or dual-pass radiator if they do frequent mountain towing with trailers.
6. Monitoring – Keep an OBD-II reader or an app handy to monitor coolant temp, fan speed, and transmission temp in real time. This will help identify whether the problem is cooling capacity, fan engagement, or something else under load.

Honestly, a lot of the stock 5.7 Hemi cooling setups are borderline for mountain towing. Upgrading cooling capacity (radiator, fans, trans cooler) plus smart driving technique is usually the solution that keeps temps in a safe range.

 

[Gero]

Ive never had any issues pulling our 6500lb camper in canada albeit not too many hills where i am.
The 180f thermostat works without having to mess around with the truck's computer? I will ve due for coolant replacement soon so I figured it would be good to proactively replace the waterpump as well as the thermostat.

 

[crash68]

The 180f thermostat works without having to mess around with the truck's computer? I will ve due for coolant replacement soon so I figured it would be good to proactively replace the waterpump as well as the thermostat.

Depends in part on the truck, the OP's truck is a Warlock that doesn't have the AGS. The shutters will close to help regulate water temperature which sorta negates the lower temp thermostat.

 

[ramffml]

Depends in part on the truck, the OP's truck is a Warlock that doesn't have the AGS. The shutters will close to help regulate water temperature which sorta negates the lower temp thermostat.

Yep, I pulled mine out at the same time I did the 180. Just reach in and remove all but 2 rows so the structure doesn't collapse but now you have permanent airflow coming in.

The 180f thermostat works without having to mess around with the truck's computer?

Yes it does. But tuning the fan to come on sooner doesn't hurt, I haven't done that yet and it's not strictly necessary.

I took this this afternoon after 1.5 ish hours of straight freeway towing. That coolant temp is about 187F, the oil temp is 221F. That oil temp is what I used to get running unloaded stock and the coolant I forget, but it was probably around 212F ish.

It really does make a big difference.

 

[Albab930]

After putting in the 180 thermostat things seem to be fine. no ECM issues either. Water got up to 225 on a couple grades and I hit 250 oil temp just once. I did change my driving and slowed down a bit when towing up hill. Guess I was expecting too much. Had towed the trailer with a Honda Pilot previously and certainly had to slow down with that. Thought I could pull up hills faster with the Ram but that’s not really proving out.
Thanks all

 

[joesstripclub]

After putting in the 180 thermostat things seem to be fine. no ECM issues either. Water got up to 225 on a couple grades and I hit 250 oil temp just once. I did change my driving and slowed down a bit when towing up hill. Guess I was expecting too much. Had towed the trailer with a Honda Pilot previously and certainly had to slow down with that. Thought I could pull up hills faster with the Ram but that’s not really proving out.
Thanks all

Thats about what I saw when I was living in Colorado and had a 1500. Towed a cargo trailer with my SxS so nothing too heavy, but a big wind sail, similar to what you tow probably. Coming up the west side of the tunnel I would have to slow as oil temp would climb to 255 to 260 if I was going over the speed limit. A lot of revs on a long steep grade and it just cant shed that much heat. There's a reason TFL calls that the Ike Gauntlet and does towing tests there.

 

[Dean2]

If I was getting Oil temps that high, I think I would be using min 5w30 and more likely a 5w40 full synthetic like Mobile 1. Glad the new T-Stat helped, along with slowing down.

 

[Wild one]

After putting in the 180 thermostat things seem to be fine. no ECM issues either. Water got up to 225 on a couple grades and I hit 250 oil temp just once. I did change my driving and slowed down a bit when towing up hill. Guess I was expecting too much. Had towed the trailer with a Honda Pilot previously and certainly had to slow down with that. Thought I could pull up hills faster with the Ram but that’s not really proving out.
Thanks all

What were your transmission temps getting to? You could look into one of @caulk04 's transmission thermostat bypasses,to help keep your 8 speed a bit cooler,and if you plan on towing fairly often,you could do a pair of remote oil filters,both will help pull heat out of the system.It also doesn't hurt to run a good quality 5W-30 .The benefit of the dual filters if you go with a set up that allows you to use the old 3/4-16 thread pitch filters,is you can hang bigger filters off it.It also doesn't hurt to run a hemi a smidge over full on the oil change,another 1/4 litre overfull doesn't hurt the hemi

 

[jawzs2]

If I was a betting guy, that coolant mix is 50-50. I’d go straight 100% coolant to fight off the lower air pressure and lower boiling temp that high elevations create.

Straight coolant is very poor at pulling heat out of metal.If anything you want to thin it down slightly from 50/50

Agreed 100%, here a chart showing the effect of different concentrations

 

[62Blazer]

After putting in the 180 thermostat things seem to be fine. no ECM issues either. Water got up to 225 on a couple grades and I hit 250 oil temp just once. I did change my driving and slowed down a bit when towing up hill. Guess I was expecting too much. Had towed the trailer with a Honda Pilot previously and certainly had to slow down with that. Thought I could pull up hills faster with the Ram but that’s not really proving out.
Thanks all

Glad it's under control, but how much was the thermostat and how much was it "I did change my driving and slowed down a bit when towing up hill".

 

[caulk04]

What were your transmission temps getting to? You could look into one of @caulk04 's transmission thermostat bypasses,to help keep your 8 speed a bit cooler,and if you plan on towing fairly often,you could do a pair of remote oil filters,both will help pull heat out of the system.It also doesn't hurt to run a good quality 5W-30 .The benefit of the dual filters if you go with a set up that allows you to use the old 3/4-16 thread pitch filters,is you can hang bigger filters off it.It also doesn't hurt to run a hemi a smidge over full on the oil change,another 1/4 litre overfull doesn't hurt the hemi

Last year I drug around a larger trailer with two sxs's and had no issues with any temps. Total weight 7k maybe a little over, oil might've hit 230 briefly, trans 160, coolant 215.

 

[62Blazer]

Agreed 100%, here a chart showing the effect of different concentrations


View attachment 573044

Keep in mind that pure water transfers heat much better than most coolant. The higher concentration of coolant, the less effective the cooling system is. There are some online notes that say going from pure water to a typical 50/50 mix of traditional coolants lowers the heat transfer ability around 20%. So running straight coolant (that is not "pre mixed") would mean the cooling system is signficantly less effective.
The main reason they have coolant/antifreeze is to alter the freezing and boiling temperatures of water. Obviously if you just ran straight water you would have issues with it freezing and ruining the engine. It does increase the boiling temp some, but that is also why they have pressurized cooling systems as that raises the boiling temps (think water boils around 250 F @ 15 psi). A lot of 50/50 mix would have a boiling temp around 265 at that pressure, so not a ton higher. Of course the other reason is corrosion inhibitors.
Basically, "coolant" is not used because it offers better heat transfer ability. It's mainly used to keep the water from freezing.

 

[mopar68]

I have a 2014 1500 5.7 Outdoorsman and changed the stock Thermostat 220 with a 180. I also took out the clutch fan and small electric fan and replaced it with a larger electric fan. I am glad that I did. Runs much cooler.

 

[vetteyog]

Just put a new 180 tstat and cap in my 2012 Ram. Running about 15 degrees cooler than with the stock one. Taking my 6500lb camper out this weekend and I'll post back what differences I have on this trip. Mine was getting in the 225-235 range before when pulling some hills.

 

[DripJust]

Has anone had any experience with your 1500 shutting down when the oil temps get around 100°c (212°f) ? I have the e fan mod and the clutch fan removed, but all summer i never had an issue, maybe bc my e fan was running alot with the ac and now its November my temps are climbing easier and the efan only turns on once the coolqnt temp gets over 200°f .
Im not forsure if its the oil temp thats causing the truck to shut down like this,its only done it a couple times in traffic while idling and it starts back with no issue and no dtc's or check lights either.
Should I try the 180° stat also ?

 

[ramffml]

Has anone had any experience with your 1500 shutting down when the oil temps get around 100°c (212°f) ? I have the e fan mod and the clutch fan removed, but all summer i never had an issue, maybe bc my e fan was running alot with the ac and now its November my temps are climbing easier and the efan only turns on once the coolqnt temp gets over 200°f .
Im not forsure if its the oil temp thats causing the truck to shut down like this,its only done it a couple times in traffic while idling and it starts back with no issue and no dtc's or check lights either.
Should I try the 180° stat also ?

Truck won't be shutting down because of those temps.

 

[DripJust]

Thats a relief and a head scratcher also. Ooufff