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Discussion Starter #1
Hi to y'all from Texas!
I have been shopping for a new truck for a while now and I really like the idea of a half ton diesel that is capable of towing 8,000 pounds, or more, as well as getting 25 MPG while not towing.
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Saturday, I took a new EcoDiesel out for a test tow. It is a nicely equipped Lone Star CC short box 4x2 20" wheels, 3.55 rear end. RAM trucks dot com shows it to have a tow rating of 7,950 and payload of 1,432lbs. I have a 1972 Airstream Ambassador. It weighs 5,700 lbs as it was towed. I did a 47 mile loop around the lake here. It was the best towing experience I've ever had. The ITBC worked flawlessly. The ride was smooth and quiet. I'm very impressed with this truck. I do have some concerns, however. I have read of some coolant and oil temperature issues with the VM Motori L630 in the Jeep GC. I wanted to tow for myself before I buy and luckily the dealer was accommodating. There is only one hill around here so I thought I'd give it a go to see how it would do. It is a short hill about 1.4 miles from the bottom to the top. It towed up the hill at 65 MPH the first time. No problem going up the hill at all. Here is a pic of the EVIC at the top of the hill. Coolant temp 230 Oil temp 244.
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The second pass, I pushed it some more. It towed up the hill at 75 MPH no problem.
Please excuse the blurry picture.
Coolant temp 235 Oil temp 253
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The ambient temp was 75. No warning lights or chimes were illuminated or sounded.
I'm concerned about engine temperatures while towing in higher ambient temps on longer hills with a fully loaded (6,800lbs), ready to camp Airstream. I know these engines run hotter than we are used to seeing, but I can't seem to find anything that would tell me at what temperature I should be concerned.

Does anyone know at what temperature the "telltale" lights illuminate for the engine oil and coolant?

If I didn't have the EVIC showing the temps, I would not have any concern as the coolant gauge was only a little past the midway mark. I know these are "biased" to not fluctuate very fast.

Also, on this test tow the truck managed 14 MPG on this 47 mile trip. Mostly highway, but about 10 miles of city as well.
IMG_1006.jpg

Your thoughts and comments are appreciated. Thanks!
 

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I saw similar temps pulling a boat last week on the longer pulls up hill. I'm thinking there is a reason these engines require synthetic oil and they do have a 21psi radiator cap which would lead me to believe they are made to run hot. I've heard the thermostat does not open fully until 222. I haven't been able to find anywhere where it states what temps are too high.
 

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Sure do like some things about your report.

First it's amazing you found a dealer who would let you test tow. WOW! Nice people there.

As for the temperatures, it's normal from lots of reports I have read.

14 mpg is great and you towed up a hill at 75 mph. WOW again.
 

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Discussion Starter #5
Thanks y'all.
I know that these temps are similar to others, however I'd like to know exactly what temp the warning buzzer and light come on.
The sales manager at this dealership didn't hesitate to allow a test tow. From my experiences so far, they have been great.
I must say I too was very impressed to tow uphill at 75MPH :)
 

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This VM Diesel runs quite a bit warmer than i'm used to. looks to be normal. I guess time will tell. we all seem to be seeing similar results.
 

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so just wondering - if the ED uses synthetic oil and "breakdown" temperature for synthetic is 350-400 degrees (seems like a fairly general range for synthetic), what would be the concern with seeing some of the ranges listed, other than maybe your own personal experience not seeing those temperatures on a gas engine or maybe never at all (unless you had Torque app)? if someone was doing a fair amount of towing and putting a lot of miles on the engine and getting temps in that 275 range, wouldn't just changing your oil a little more frequently give you a comfort factor? i guess i'm not seeing the problem if the ED "runs hot" as long as it "runs hot" in the tolerances of what it was engineered for... i'm looking for smarter people to answer as i really am trying to learn, not stating that i'm right :)
 

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so just wondering - if the ED uses synthetic oil and "breakdown" temperature for synthetic is 350-400 degrees (seems like a fairly general range for synthetic), what would be the concern with seeing some of the ranges listed, other than maybe your own personal experience not seeing those temperatures on a gas engine or maybe never at all (unless you had Torque app)? if someone was doing a fair amount of towing and putting a lot of miles on the engine and getting temps in that 275 range, wouldn't just changing your oil a little more frequently give you a comfort factor? i guess i'm not seeing the problem if the ED "runs hot" as long as it "runs hot" in the tolerances of what it was engineered for... i'm looking for smarter people to answer as i really am trying to learn, not stating that i'm right :)
Not a simple issue.

"Full" synthetic oils can get quite hot before significant breakdown.

Some engines characteristically have very high oil temps. Air cooled engines and turbo engines on the track, are good examples.

Over time we will learn what the normal range of oil temps are for our engine, so we'll get a feel for what is too hot. If your oil hits 275deg and that is unique among your forum buddies, it's time to be a little concerned no matter what the breakdown temp of your oil.

We're likely to never get an authoritative answer on what the max oil temp was that the engine was "engineered for." Even if we did get an official answer, it wouldn't be believable because the answer was produced by a committee that included far more marketing wonks, lawyers and accountants then engineers. General rules of thumb are figured out for these kinds of things by engine builder types that accumulate significant experience pushing the engine to the limits of it's capability. Short of that all we have is general rules of thumb and the accumulated experience of our forum buddies.

That said, I wouldn't worry overmuch about oil temp. If a person is determined to worry about something, they should worry about coolant temps. The oiling system is far more robust. Also, reasonable coolant temps are a significant factor in keeping oil temps low. The reverse is not true.
 

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Yah and that's what I find strange about this thread. The poster wasn't pulling that much, it was cool out and he wasn't going that fast up the hill. Granted we don't know what the hill really looked like but he doesn't make it sound that aweful. I just wonder if it's because there were no miles on the truck? Or possibly something's even wrong with the test vehicle. Maybe thermostats not fully opening, radiator is clogged etc.

Based on his tow experience I don't think I would buy the truck. A lot of other people have towed more weight though without issue. Honestly I've never seen a similar towing account on this forum.
 

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Discussion Starter #16
Could have been something wrong with the truck. Don't really know. Someone else around here is driving that one. :) The hill is fairly steep (5%), but not very long.

The next time I'm hitched up with my truck, I'll tow up the hill to see what numbers I get.
 

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maybe to high of a gear , what rpms where you running ?
 

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Here's mine from last weekend. Rolling hills, nothing extreme.
Didn't get close to what the OP was seeing.
My rig is an Laramie CC with two pkg, and the TT is an 21" Rockwood Roo tipping a the scales at just under 5k.
 

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Your temps are good if no l,ights turned on, setup the extra guages on the dash so you can see how high those temps get, it gives you a bar guage I am sure those temps you seen would only be a little over 3/4 on the bar guage
 
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