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Discussion Starter #1
There's long been discussions re. high oil temps causing deration, but how do we know it's the hot oil causing the deration and not hot coolant? When an engine derates because of high temp, does a message come up on the EVIC that warns the driver re. hot oil temp?
 

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There is derates for coolant, oil, and egts I dont remember the exact message but it warns about high temps and possible speed reduction. If I remember correctly coolant is 245 F oil is 268 F and egts are 1550 F. But its been a few years since I've had to worry about those temps so I might have the numbers wrong. These were my peak temps with a stock cooling system but tuned.
88875
 

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Discussion Starter #3
Thanks for the threshold info. So when the EVIC warns of high temps, does it explicitly say oil or coolant? I mean there's been years of discussion re. derates due to oil temps. We know it's oil temps right? We're not just guessing?
 

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Thanks for the threshold info. So when the EVIC warns of high temps, does it explicitly say oil or coolant? I mean there's been years of discussion re. derates due to oil temps. We know it's oil temps right? We're not just guessing?
Ive only hit coolant temps high enough for a derate once but at that time I had a tune which disabled the derates. Ive always hit oil derate temps which prevent the coolant from getting hot enough. It used to be I would hit derates almost every weekend when towing but I live near 6-9% grades and towed up them often.
 

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Discussion Starter #5
So knowing what caused the derate is simply a matter of knowing what the max temps are? The EVIC doesn't tell you what temp sensor is triggering the derate?

Re. hitting derates every weekend. Geeze, man, that would be intolerable. I only tow monthly and there isn't a real hill within hundreds of miles. Surely you're tempted to trade up from our little 3.0 liter?

We are in very different situations. In your situation, I can certainly understand being decisively engaged on mitigating the derate. Only because I have never hit a derate do I have the luxury of abstractly deciding that I don't like my coolant temps.
 

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Ive only hit coolant temps high enough for a derate once but at that time I had a tune which disabled the derates. Ive always hit oil derate temps which prevent the coolant from getting hot enough. It used to be I would hit derates almost every weekend when towing but I live near 6-9% grades and towed up them often.
My bet would be EGT, I have owned 2 ecodiesels now and never had a concern about heat the cooling system is actually impressive. I pull my TT which is max GVW for my truck up really long steep hills and my EGT has hit 1450 deg F so I had to back off, but oil temp, coolant ect were all good.
 

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So knowing what caused the derate is simply a matter of knowing what the max temps are? The EVIC doesn't tell you what temp sensor is triggering the derate?

Re. hitting derates every weekend. Geeze, man, that would be intolerable. I only tow monthly and there isn't a real hill within hundreds of miles. Surely you're tempted to trade up from our little 3.0 liter?

We are in very different situations. In your situation, I can certainly understand being decisively engaged on mitigating the derate. Only because I have never hit a derate do I have the luxury of abstractly deciding that I don't like my coolant temps.
Higher trim models have a screen you can watch the actual temps for coolant, trans, and oil which are accurate but it also shows oil pressure which isn't measured on the same screen. Ive got no interest in trading mine I decided to just fix that areas fca screwed up on. Daily driving a 2500 is not for me ive done that in the past.
 

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My bet would be EGT, I have owned 2 ecodiesels now and never had a concern about heat the cooling system is actually impressive. I pull my TT which is max GVW for my truck up really long steep hills and my EGT has hit 1450 deg F so I had to back off, but oil temp, coolant ect were all good.
These engines are rated by vm motori for sustained egts of 1550 F. While running a race tune I've hit 1750 F without issue but everything gets hot quick.
 

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Discussion Starter #9
Higher trim models have a screen you can watch the actual temps for coolant, trans, and oil which are accurate but it also shows oil pressure which isn't measured on the same screen. Ive got no interest in trading mine I decided to just fix that areas fca screwed up on. Daily driving a 2500 is not for me ive done that in the past.
I have a Laramie so I watch those temps all the time. Kinda obsessively actually. So you're saying, if I understand correctly, that the truck does not tell us which fluid triggered a derate. Since most folks probably don't know the configured limits like you do, almost everyone that gets a derate is guessing as to the cause?

Re. oil pressure. Since that's calculated, I would argue that it's just marketing. It's not "real."
 

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I have a Laramie so I watch those temps all the time. Kinda obsessively actually. So you're saying, if I understand correctly, that the truck does not tell us which fluid triggered a derate. Since most folks probably don't know the configured limits like you do, almost everyone that gets a derate is guessing as to the cause?

Re. oil pressure. Since that's calculated, I would argue that it's just marketing. It's not "real."
I dont remember it telling me which temp its derating for more of a hint that it might derate.
 

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I have a Laramie so I watch those temps all the time. Kinda obsessively actually. So you're saying, if I understand correctly, that the truck does not tell us which fluid triggered a derate. Since most folks probably don't know the configured limits like you do, almost everyone that gets a derate is guessing as to the cause?

Re. oil pressure. Since that's calculated, I would argue that it's just marketing. It's not "real."
I've hit the hot oil warning of 265º three times and the dash on my Laramie did tell me it was due to oil temp. I couldn't tell you what specifically the dash said as I've had my external oil cooler for some time now.
 

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Discussion Starter #12
I dont remember it telling me which temp its derating for more of a hint that it might derate.
Interesting. Good to know. Those are serious hills you climb. I got a new trailer last spring. Better quality so it's heavier, but I don't usually have to pull up real hills. Every couple years I'll race at Mid-Ohio or Watkins Glen (NY) and that requires I pull over the Appalachians, but even they aren't real mountains. I grew up in western OR/WA. Couldn't drive 90min east w/o going over mountain passes.

A couple months ago I swapped out the trailer's batteries for Lithium, and now using solar instead of a generator. Reduced load by 400lbs so that got me down to 8100lbs.
 

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Discussion Starter #13
I've hit the hot oil warning of 265º three times and the dash on my Laramie did tell me it was due to oil temp. I couldn't tell you what specifically the dash said as I've had my external oil cooler for some time now.
Ah so, that's big. So if a person has the higher tier display, the computer tells them the cause of the derate. Good to know, thx.
 

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A couple months ago I swapped out the trailer's batteries for Lithium, and now using solar instead of a generator. Reduced load by 400lbs so that got me down to 8100lbs.
Not a bad weight, that's what my Toy Hauler averages but I pull a TON of wind along with that weight, which makes a large difference. Most I've had my TH at is #8900 and I had a quad in the bed.
 
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Interesting. Good to know. Those are serious hills you climb. I got a new trailer last spring. Better quality so it's heavier, but I don't usually have to pull up real hills. Every couple years I'll race at Mid-Ohio or Watkins Glen (NY) and that requires I pull over the Appalachians, but even they aren't real mountains. I grew up in western OR/WA. Couldn't drive 90min east w/o going over mountain passes.

A couple months ago I swapped out the trailer's batteries for Lithium, and now using solar instead of a generator. Reduced load by 400lbs so that got me down to 8100lbs.
Ive sold my snowmobiles/trailer and the travel trailer is now parked long term its being used as a second house so little to no towing for me now. But im sure that well change someday.
 

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Ah so, that's big. So if a person has the higher tier display, the computer tells them the cause of the derate. Good to know, thx.
I've never experienced a derate where the ECM pulls fuel to bring temps down, I've always backed off at the 265º dash warning.
 

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Mine is only a Big Horn but displays water trans & oil temps. Believe GDE said after 244 water or 266 oil she will start to derate or pull fuel & timing relative to temps. Have only been to 244 water once and was also at 266 oil at the same time. Think the temp was 105 that day. Have been to or near 266 oil many times. Have had oil temps from both grades and pulling into wind going too fast dragging a box TT/TH. 239 water turns off the AC.

You can pretty easy manage oil temp by limiting throttle going up a grade. Simply limit sustained rpm to 3,000 and she won't derate even up a miles long grade. Have taken 9k up 5 & 6 percent and it will pull the truck down to 50 mph WOT over 3k and it would eventually derate. Mine GDE tunes, 3.92, 32.5 tall tires, honeycomb grill. I've never let it derate but have read on this forum of people just WOT into derate and hold it WOT while truck eventually slowed down to 15 mph. I would have climbed the hill a little slower somewhere up the hill but never derated by throttle / temp management and topped the hill at 50 mph. Usually with 3 lanes or 2 truck lanes. Be semi trucks going 25 mph in right lane me going 50 in middle lane and some 4 wheeler in the hammer lane at whatever 75.

So its not a Cummins but with my usual 6 to 7,500 pound TT and not more than 6 percent up any long interstate grade its easy to do with a little management.
 
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Discussion Starter #19
Ive got a laramie as well but mine is a 2015 im dumb enough to just let it derate wonder if the messages are different for some years?
Good question. Folks talk about the derate a lot but we're still kinda lean on hard info. Heck, even a flash could change the Derate temps and messages. So much we don't know.

I mentioned, in the thread re. radiators, that my magazine article got reviewed by a RAM engineer. I didn't actually talk to him, it was the magazine editor that talked to him. I'd love to buy him beer all night and pick his brain, but he's apparently in California and I'm in GA. It'd be terrific to have some real insights as opposed to having to extrapolate from scanty info and guess.
 

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So knowing what caused the derate is simply a matter of knowing what the max temps are? The EVIC doesn't tell you what temp sensor is triggering the derate?

Re. hitting derates every weekend. Geeze, man, that would be intolerable. I only tow monthly and there isn't a real hill within hundreds of miles. Surely you're tempted to trade up from our little 3.0 liter?

We are in very different situations. In your situation, I can certainly understand being decisively engaged on mitigating the derate. Only because I have never hit a derate do I have the luxury of abstractly deciding that I don't like my coolant temps.
A great last sentence! Explains a lot to many I expect.
 
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