Ideal Temperatures for Cummins Engines

[22RAMAlazan]

Hello All, I always hear/see people talking about ideal temperatures for various systems of a Ram truck. Now as a first time diesel owner I would rely on temperatures on the gauges. Red means either slow down or stop and thats about it. I never really paid attention to the exact temperature of the gauge. If it got to red, be careful or the truck will tell you (per the gauges or notification). Is there anything the truck will NOT tell me that I should always keep an eye on? This goes for all systems of a Ram truck 2500-3500, such as engine, coolant, transmission, etc. What are your thoughts?

 

[tolym]

Oil temp isn’t accurate so I wouldn’t worry about that one.
Coolant should be around 190-200 that’s just cruising down the road. When towing and climbing some hills, it can spike up to 215-220 and I wouldn’t worry about it. If you get passed 220 let of it a little.
Transmission temps are around 170. You won’t see much higher unless you’re towing heavy in stop and go traffic.
Try not to get much higher then 215.


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[Brutal_HO]

Highest temps I saw pulling 16K up and over Wolf Creek Pass both ways, or in Co Springs rush hour, was around 215 coolant/oil (they tend to run similar), 170 trans (HO). A 68RFE might run a little hotter. Normal on the Aisin is around 165 unless pulling hard. If you get out of TC lockup, trans temps are gonna spike up more.

 

[22RAMAlazan]

Thank you both for the input! I will make sure to keep on eye on it. I appreciate the info!

 

[H3LZSN1P3R]

Highest temps I saw pulling 16K up and over Wolf Creek Pass both ways, or in Co Springs rush hour, was around 215 coolant/oil (they tend to run similar), 170 trans (HO). A 68RFE might run a little hotter. Normal on the Aisin is around 165 unless pulling hard. If you get out of TC lockup, trans temps are gonna spike up more.

The 68rfe seems to stick at 165 aswell

 

[Firebird]

I just finished a 600 mile run pulling 9000 pounds. Coolant ran between 188 and 194, trans sat at 170 the whole trip

 

[tolym]

I just finished a 600 mile run pulling 9000 pounds. Coolant ran between 188 and 194, trans sat at 170 the whole trip

Those are nice and cool temperatures. Was it cool outside? I have a 4th gen and I know they worked on cooling to keep the newer ones cooler.
Waiting on my ordered 22.


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[Firebird]

Those are nice and cool temperatures. Was it cool outside? I have a 4th gen and I know they worked on cooling to keep the newer ones cooler.
Waiting on my ordered 22.


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No, it was hot and humid, so I'm happy with those temps

 

[22RAMAlazan]

So in general, if i see anything over 215 degrees let off a little...... Also, when I let off, does that mean take it a bit slower or does that mean pull over and turn off or pull over and let idle? I hear leaving cummins in idle is a no go but then i read the manual and it says let idle for minutes at a time.

 

[H3LZSN1P3R]

So in general, if i see anything over 215 degrees let off a little...... Also, when I let off, does that mean take it a bit slower or does that mean pull over and turn off or pull over and let idle? I hear leaving cummins in idle is a no go but then i read the manual and it says let idle for minutes at a time.

Use high idle when idling for extended periods, also depends on the situation if pulling a hill yes let off if its just lugging to much then drop a gear and you will see the temps settle down

 

[22RAMAlazan]

What would you consider long periods of idle? 10 mins or more?

 

[tolym]

What would you consider long periods of idle? 10 mins or more?

Diesels idle for hours without issues as long as you take it on the interstate after and run it for up to 30 mins to clear all that soot build up during idling. If deleted, then it can idle for days.


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[22RAMAlazan]

i doubt I would idle for hours.... I use it as a daily driver and tow every a few times every few months.

45 miles to work on highway majority
45 miles back home on highway majority

Should I use high idle or just idle when i get home?

When should I use high idle? Quick store errand?

 

[gimmie11s]

Meh.

You arent working the truck if the fan doesnt come on at the 228* mark at some point in your tow.

 

[tolym]

Meh.

You arent working the truck if the fan doesnt come on at the 228* mark at some point in your tow.

228? I thought it was at 218 or 219.
I’ve heard my fan on my 4th Gen towing on a hot day but it was around 218-219 I think.


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[tolym]

i doubt I would idle for hours.... I use it as a daily driver and tow every a few times every few months.

45 miles to work on highway majority
45 miles back home on highway majority

Should I use high idle or just idle when i get home?

When should I use high idle? Quick store errand?

You’re overthinking this. That’s plenty of driving back and forth so no need to idle anything. Only idle it when it’s cold before you hit the road. To warm it up faster when it’s cold, turn on exhaust break and it’ll warm up very quick.


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[elephantrider]

analysis paralysis. get in turn it on and hit the go pedal.

 

[Great White North Eh]

i doubt I would idle for hours.... I use it as a daily driver and tow every a few times every few months.

45 miles to work on highway majority
45 miles back home on highway majority

Should I use high idle or just idle when i get home?

When should I use high idle? Quick store errand?

Only use hi-idle when Greta walks past.

 

[Brutal_HO]

228? I thought it was at 218 or 219.
I’ve heard my fan on my 4th Gen towing on a hot day but it was around 218-219 I think.


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I think it is more like 208. I do know that my fan has kicked into high gear on a few hard pulls so my statement of seeing 215 was perhaps a bit off.

"Per Cummins Quickserve Service Manual 6.7L Specs, standard coolant temps should be between 186-207°F, and maximum is 225°F. Maximum oil temp is 280°F."

 

[elephantrider]

Only use hi-idle when Greta walks past.