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Need info from 3.6 and 5.7L JGC cooling while towing

7K views 36 replies 14 participants last post by  Capt Bligh 
#1 ·
Hi Guys, I from the ecodiesel side of the house. Just trying to understand your coolant temperature gauge response when you put your Jeeps under load ether towing, going up a hill or even a strong headwind. I have attached a couple of threads on this discussion. Let me know your experiences please.
Update: FYI diesel thermostat opens at 208deg and fully open at 225 deg. I would assume you guys run thermostat fully open at 190-200? Assumption since the gauges are the same no calibration difference the Ecodiesel is going to run hotter. But it seems to run up to orange too easily under load. Tran temp is usally 199-203, oil temp maybe up to 255 when under load. So what do you guys experience.:confused: Mike



Did you notice your temperture rising when you hit the hills. My coolant temperature guage seems to climb to the upper part of the third quadrant consistently when I hit a hill or a good head wind. I'm only towing 2500lbs. Other members have seen the same thing. I feel the cooling system is undersized.


Akinney: Thanks for the response. I too have looked all over the net and have seen that some of the guys on the RAM site have said fully open at 228degF. I'm trying to validate that number buy asking engineering at Jeep. I sent them the part number. Also sent the same question to a vendor that sells the thermostat. I will let you know what I find out. Wish we had a gauge like the Rams. Akinney how about this theory. If it is true like you said that it opens up fully at 225-228. Then maybe our temperature gauge which is the same for the 5.7 and 3.6 gas engines is not calibrated for our ecodiesel thermostat. So when it gets hot to the point where it opens fully it's at the high side of our guage, where on the gas engines when they open fully at the lower temperature the neddle is dead center or just below center. Just hate depending on a idiot light to tell me it got too hot. I will let you know what I find out. And it is comforting that no one on the RAM site or the Jeep ecodiesel site have had an over heating issue. Mike
 
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#4 ·
Year? Engine? Factory tow package or not? When did the symptoms start? What are the symptoms? How long have you owned the vehicle? No changes over this time? Are you losing coolant? Is it actually running hot or are you concerned that it may climb higher and start running hot?
 
#3 ·
I was pushing my 5.7 with tow package (summit) really hard on some nasty grades few months back. My coolant temps never moved off of the first segment on the gauge in fact i have never seen coolant move past that first mark in 4 years of owning it. Trans temps stayed normal like the coolant but the oil temp did go up and got into the high 240s which is not terrible but just higher than im used to seeing. Had i been towing near limit on grades lke that im curious or maybe a bit worried what those oil temps would have been.
 
#6 ·
sounds to me like you have a coolant flow issue or the fans are not coming on at the right temp. I would lean toward the thermostat going bad but I would not rule out the water pump or even the radiator.

I had a cummins spin the hub on the water pump and only over heated on hills. Low rpms it would still cool but high rpm the impeller wouldn't keep up with the shaft.
 
#7 ·
Yes I tow with a 2011 WK2 3.6. Yes it wants to overheat when towing in the mountains. I changed out the thermostat. No change. I changed out the radiator for a two row radiator. No change. I now run E85 when possible when I tow. Helps, but doesn't fix the problem. My 2015 WK2 3.6 does exactly the same thing when towing. Both vehicles have skid plates, and towing packages. Note: transmission temps never budge, nice and cool.

Current theory is that the skid plate package blocks air from getting out of the engine compartment. I am looking for some good hood vents that are not too ugly. Help?

I am also looking for a way to tie in an auxiliary oil cooler. Again, help?
 
#9 ·
The Diesel has a 12 quart cooling system capacity, the v6 has 10.4 quarts and the v8 5.7 has 16 quarts. Maybe they undersized the system for towing near rated limits. Could you put the larger hemi radiator in it possibly? Also saw someone saying their diesel goes into limp mode when coolant hitting 290-295 degrees you could get a gauge to monitor so you dont get into that range.
 
#11 ·
Both of my 3.6 WK2's (a 2011 and a 2015, both with towing packages and skidplates) behave identically, so not so likely a bad thermostat, water pump, electric fan, etc. They just can't handle Guadalupe pass in 104F degree heat with 3500# of boat on the back. However, when I pull over, temps drop to normal immediately, within seconds. That leaves either inadequate cooling passages, or inadequate air flow through the radiator. I am not seeing discussions of overheating issues with the 3.6 in the Ram 1500, other than issues with grill slats not opening. That provides hope the 3.6 engines' cooling passages may be adequate. And when you look at the WK2 engine compartment there isn't really anywhere for hot air to exit, especially with the skidplates installed.

So, to quote David Freiburger of Roadkill, "When it overheats, take the hood off".....throw the hood in the trailer at the bottom of the pass, drive on, and see what happens. If that fixes it, its time for hood vents.
 
#13 ·
Governor, I guess I could try that. But I think the issue is the coolant capacity. The 5.7L uses 16 quarts. The ecodiesel with more torque, runs hotter and has the same max tow value, only has a coolant capacity 12 Quarts. That is quite a bit smaller. Don't know if you can switch radiators.
 
#14 ·
If it was coolant capacity the problem should show up on every diesel. The fact that so many are reporting no problems makes me question that which would lead to more individual solutions. Pressure in the system allows higher temps above normal boiling temp. If the cap is weak and pressure low the boiling point will occur at a lower temp. Maybe I'm off base but it might be worth it to try.
 
#16 ·
Akinney: Thanks for the response. I too have looked all over the net and have seen that some of the guys on the RAM site have said fully open at 228degF. I'm trying to validate that number buy asking engineering at Jeep. I sent them the part number. Also sent the same question to a vendor that sells the thermostat. I will let you know what I find out. Wish we had a gauge like the Rams. Akinney how about this theory. If it is true like you said that it opens up fully at 225-228. Then maybe our temperature gauge which is the same for the 5.7 and 3.6 gas engines is not calibrated for our ecodiesel thermostat. So when it gets hot to the point where it opens fully it's at the high side of our guage, where on the gas engines when they open fully at the lower temperature the neddle is dead center or just below center. Just hate depending on a idiot light to tell me it got too hot. I will let you know what I find out. And it is comforting that no one on the RAM site or the Jeep ecodiesel site have had an over heating issue. Mike
Sounds like a good theory.

It's interesting that the Hemi got a larger cooling system. My build sheet shows the "heavy duty" cooling system as part of the ORA2/towing package. I'm not sure if every Ecodiesel gets the "heavy duty" cooling system. Is "heavy duty" cooling the same capacity on the gas V6?
 
#17 ·
Akinney: I have the towing package also. Look at your specs in the diesel supplement. Ecodiesel 12.2 Quarts. Then check the general owners manual. 3.6 is 10 Quarts. and 5.7L with tow package 16 quarts. I bet we need the 5.7L cooling capacity for our diesels.
 
#19 ·
The Hemi doesn't run "cool" for sure...using the same analogy as the previous poster, one can probably "fry eggs" on the hood after it's been running for a bit! I'm not surprised that the HD cooling with the Hemi is substantial, but yea...it's consistent if one monitors the temps, in my experience. I bet there would be a rise with heavy hauling, however. I think I got one or two degrees up while hauling both horses about 15 miles each way; about a 6000 lb load including the trailer plus two people.
 
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#20 ·
3.6 w/tow pkg/HD cooling:

I haven't towed yet but using the gauge screen on the offroad pages I get a digital coolant temp and it's never been above like 206 or so. I tried to get it to run hotter today by downshifting to keep RPMs up and it wouldn't budge. It was on a decent climb but it was cool out.
 
#21 ·
I'm not sure the capacity has anything to do with it we are only talking a gallon. The capacity may only be different because of the block capacity and the radiators may hold almost the same amounts.

It has to be something to do with cfm over the radiator or coolant flow. If the radiator can cool the fluid and the pump can move it the vehicle should stay cool. If these where all vehicles with non oem motors or parts things could be different.
 
#22 ·
Maybe it's because we have an intercooler ahead of our radiator on the Ecodiesel? Blocks some air flow and adds some heat load when the turbo is run hard.
 
#25 ·
Well looking into the HD cooling vs the standard a bit here is why the Hemi stays cooler, these are the radiator sizes;

25 1/16" X 20 1/4" X 1" HD cooling

25 1/16" X 20 1/4" X 5/8" Standard cooling

There are two different fans listed also with the HD fan looking like it moves way more air than the standard. I did forget to save the pics I found but Ill try to dig them up.

I am not sure which set up comes on the diesel as I didn't dig that far. Hope this helps
 
#30 ·
Based on the coolant capacity it doesn't seem very heavy duty. I would assume maybe they gave us oil coolers and trans cooler but I don't know. I have contacted FCA about the temperature items in the ecodiesel thread. Appreciate your help with these temperatures issues. I still find it interesting that 5.7L has no issues when towing as far as temp's getting to the Orange.
 
#32 ·
I didn't see it posted before but is the coolant temp actually getting to the high end of the temp range in actual temp, have you verified temp with another source. If the sender is bad it could be showing high at all temps.....or incorrectly? Just a thought. I've seen bad senders do crazy things.
 
#33 ·
If you saw from my original post, I'm from the Ecodiesel side of the house. I was trying to see how the 5.7L cooling system responds to towing under load.
All most all the ecodiesel's report as they tow under load the needle tends to creep up towards the beginning of the orange. Which is about 240deg acording to a members scan tool. My feeling is that the ecodiesel cooling system is not up to the job. For example the 5.7L has a 16quart cooling system. The Ecodiesel has a 12.2 Quart. Also our thermostat begins to open at 208 deg and fully open at 225deg. I assume the gas engine is fully open at 200-205deg. The diesel is designed to run hotter. Also trying to find out at what temperature the "Engine temperature hot" message come on for the diesel.. Does anyone no the answer to that? I have been told you actually need the shop manual to see that value. It's not in our owner's manual. I also have a call into FCA about this
 
#34 ·
I've had my 2013 5.7 tow pkg for a little over a month now. I usually put the digital coolant temp gauge up when driving and the hottest I've seen (traffic jam) is ~210F. Usually it gets to 203F and stays there. I have not towed yet but plan to, bought the jeep to occasionally tow the car to the track.


Speaking of which, I haven't checked myself, but how well is the radiator shrouded on the eco diesel/hemi? Is all the air coming through the bumper/grille forced to go through the intercooler/radiator? A good setup will have shrouding all the way around and not have gaps where air could bypass the radiator and go around or under it.


On my track car I made shrouding using sheet metal to make sure all air was going through the radiator. It made a big difference in keeping the car cool during the ~25min track sessions. I've heard of guys using coroplast to shroud it as well.
 
#37 ·
Well, we did the great David Freiburger cooling test when we were out in Elephant Butte, New Mexico. We took the 2015 WK2 towing the boat out on I-25 at about mile marker 95 on a balmy 100 degree afternoon. Oil temp (the 2015 doesn't have digital readout for water temp) promptly went to 240 in the first mile and a half of grade. We then removed the hood, and repeated the test. No change. Looks like a design limitation internal to the engine.
 
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