Grand Cherokee Running Warm Towing

[Nick1994]

Today I flushed the coolant which was really clean and replaced the thermostat and radiator cap. I went against my own rule and used an aftermarket thermostat and radiator cap. The thermostat is on National back order according to the dealership. AutoZone's Duralast thermostats are reboxed Motorad, which is OEM for my old Jeep so I guess that's something. I used Prestone Dexcool which is supposedly good for Jeeps. 70/30 ratio distilled water/antifreeze.

I did about 4 heat ups and cool downs and cracked open the bleeder on the thermostat housing. Still have some stray bubbles in my no-spill funnel.

I'll be out of town for the next couple weeks and won't be able to test anything out until then. I'd like to do a head gasket combustion test too.

Is there any way you can shine a flashlight from the engine compartment forward through the radiator/condenser and see how much light comes through? When I do this, I see all the air channels are completely open and clear of any debris. As I said before, I'll bet you the problem with your overheating is blockage in the air channels either in the condenser or the radiator or both.

Nice and clear

 

[Bailes1992]

I think you dont' have enough power to pull up inclines. A sub 4 liter non turbo engine pulling 3200lbs on a 100f day. Besides weight, the trailer is a good bit taller that the tow vehicle. Yes the trailer is pretty aero, but think about how the air comes off the jeep and probably hits the trailer just above the tongue mounted tool box. Plus the air over the top dragging on the roof.

The long tear drop shape probably has a lot of down force on the rest of the trailer past the roof peak.


BTW your tow chains look a bit close to the pavement, but it could be an optical illusion.

Not sure I agree with that at all.

I've towed our 1300kg (~2900lbs) caravan with my Dacia Duster up long inclines for several miles at a time in 30°c+ days with no issues at all. The Duster sports a small 1.5 turbo diesel engine with just 115bhp.

 

[skyactiv]

I’d plug in a Bluetooth single and use an app in your phone to see the coolant temperature

 

[spasm3]

Not sure I agree with that at all.

I've towed our 1300kg (~2900lbs) caravan with my Dacia Duster up long inclines for several miles at a time in 30°c+ days with no issues at all. The Duster sports a small 1.5 turbo diesel engine with just 115bhp.

Look at the height and wind resistance of your camper vs a caravan. It's not just about weight.

 

[Bailes1992]

Look at the height and wind resistance of your camper vs a caravan. It's not just about weight.

Our caravan is quite a bit less aerodynamic than the OP's I suspect.

 

[spasm3]

Not sure I agree with that at all.

I've towed our 1300kg (~2900lbs) caravan with my Dacia Duster up long inclines for several miles at a time in 30°c+ days with no issues at all. The Duster sports a small 1.5 turbo diesel engine with just 115bhp.

Your dancia duster weighed 2900lbs plus the 2900lb caravan =5800lbs plus your loading.

Grand Cherokee 4895lbs plus your 3200lbd camper = 8095lbs plus loading.
5800lbs vs 8095lbs.

I don't think you can compare the two.

 

[Bailes1992]

Your dancia duster weighed 2900lbs plus the 2900lb caravan =5800lbs plus your loading.

Grand Cherokee 4895lbs plus your 3200lbd camper = 8095lbs plus loading.
5800lbs vs 8095lbs.

I don't think you can compare the two.

So the train weight of my setup is 71% of the OP's.

However, my little 1.5 4 cylinder turbo diesel engine only has 48% of the power (115bhp vs 238bhp). Edit: Just found out the power output of the Jeep 3.6 is 262bhp, so I have just 43% of the power output.

And there we have it... a comparison.

 

[spasm3]

So the train weight of my setup is 71% of the OP's.

However, my little 1.5 4 cylinder turbo diesel engine only has 48% of the power (115bhp vs 238bhp). Edit: Just found out the power output of the Jeep 3.6 is 262bhp, so I have just 43% of the power output.

And there we have it... a comparison.

Torque moves weight. The dancia is around 195 ft/lbs the jeep 260. So torque per pound is not far apart between the two.

 

[Bailes1992]

Torque moves weight. The dancia is around 195 ft/lbs the jeep 260. So torque per pound is not far apart between the two.

Torque is just a turning force. Power is ultimately what moves the vehicle.

Even then, I'm running 75% of the torque the Pentastar is. That also makes it a fair and reasonable comparison.

 

[Nick1994]

I’d plug in a Bluetooth single and use an app in your phone to see the coolant temperature

I have, you can see post #25

 

[spasm3]

I have, you can see post #25

Nick, can you see the transmission temps with blue tooth, when the coolant temps are 240+ ?

I would be concerned with the radiators ability to cool the trans when it's overwhelmed with coolant temp.

 

[spasm3]

I have, you can see post #25

Nick, can you see the transmission temps with blue tooth, when the coolant temps are 240+ ?

I would be concerned with the radiators ability to cool the trans when it's overwhelmed with coolant temp.

 

[spasm3]

At this point with it going into limp mode from heat, I would pull the water pump and check for an eroded impeller.

Seems that is one thing that is rare but could cause the symptoms you describe.

 

[Nick1994]

Nick, can you see the transmission temps with blue tooth, when the coolant temps are 240+ ?

I would be concerned with the radiators ability to cool the trans when it's overwhelmed with coolant temp.

Transmission stays nice and cool, 215 or lower.

 

[Nick1994]

I haven't taken the trailer out yet but today I replaced the radiator. Found out there was a "Heavy-Duty" cooling option on these and Rock Auto sells thicker radiators. I went with a Denso radiator. The standard cooling radiator is 5/8" thick while the HD ones are 1" thick. The book procedure says you have to take the bumper off to replace the radiator, but that wasn't necessary. Also replaced the radiator hoses while I was in there and didn't put back in that dumb beauty cover on top of the engine, it probably holds in heat too I'm guessing. And I changed the oil early, only had 3,500 miles or so on it.

Will take the trailer out in the next week as a test. This has to work, as it's pulling the camper on a 1,600 mile round trip to Lake Tahoe in 2 weeks...

 

[dishdude]

I haven't taken the trailer out yet but today I replaced the radiator. Found out there was a "Heavy-Duty" cooling option on these and Rock Auto sells thicker radiators. I went with a Denso radiator. The standard cooling radiator is 5/8" thick while the HD ones are 1" thick. The book procedure says you have to take the bumper off to replace the radiator, but that wasn't necessary. Also replaced the radiator hoses while I was in there and didn't put back in that dumb beauty cover on top of the engine, it probably holds in heat too I'm guessing. And I changed the oil early, only had 3,500 miles or so on it.

Will take the trailer out in the next week as a test. This has to work, as it's pulling the camper on a 1,600 mile round trip to Lake Tahoe in 2 weeks...

View attachment 172675View attachment 172676

Yes, it was actually a common standalone option. My 2021 had the towing package that included HD cooling, full size spare, self leveling rear struts, tow receiver and wiring for trailer lights. It was like $995.

 

[ctechbob]

Our caravan is quite a bit less aerodynamic than the OP's I suspect.

View attachment 167533

FARRRR off topic, but man do I get the heebie jeebies when I see UK/Euro trailers with the wheels in the middle.

 

[AZjeff]

Nick, you gauge only shows red at the very end so Jeep must think you're good until you get there. Compared to the gauge in my Wrangler that gets into the red 3/4 of the way over and maxes out at 260 indicated. Get an OBD2 bluetooth dongle thingie and download the Torque app on your phone.

 

[Nick1994]

Nick, you gauge only shows red at the very end so Jeep must think you're good until you get there. Compared to the gauge in my Wrangler that gets into the red 3/4 of the way over and maxes out at 260 indicated. Get an OBD2 bluetooth dongle thingie and download the Torque app on your phone.

I got OBD temps, you can see in post #25 in this thread

 

[AZjeff]

I got OBD temps, you can see in post #25 in this thread

Missed that part. Hope the new rad fixes it, I wouldn't leave on a trip knowing it was running that hot. No reserve. At least you can run the 93 out of town and miss taking the 17 north, that would kill the Jeep.