Oil Temp

[mwilson]

The temp should be close on the two, but with our small sump the oil temp has the potential to clime 25-50° above the coolant in a long hard pull. I have heard from from those who measure it that it doesn't go much above that.

As far as emissions, the emissions stuff doesn't care about oil temp or pressure so it really doesn't need to know



The last one I looked up didn't have one.

Yes, the small sump may influence that. A rear gear train 6.7 Cummins in a Freightliner M2 holds around 20 quarts instead of 12.

I was amazed after driving my first big rig with an oil temp gauge. I had always thought oil temps would be high similar to an automatic transmission but day after day the coolant and oil temps would run about the same. They would climb together going up a grade and then drop together when the all or nothing Horton fan clutch kicked in.

Transmissions and driving axles are a different story however.....

 

[mwilson]

Only 1 sensor is listed. Cummins uses that same sensor for oil, coolant and fuel temps for various application. If your truck had the oil temp functionality I believe that there would be a call out for 2 sensors instead of 1.

I did find where the newer Cummins harness (used on many engine applications, not just ours alone) has a spare plug to add an oil temp sender but that would not work in our CTD applications.

So it's a guess or an algorithm, maybe a combo of both......

 

[AH64ID]

Yes, the small sump may influence that. A rear gear train 6.7 Cummins in a Freightliner M2 holds around 20 quarts instead of 12.

I was amazed after driving my first big rig with an oil temp gauge. I had always thought oil temps would be high similar to an automatic transmission but day after day the coolant and oil temps would run about the same. They would climb together going up a grade and then drop together when the all or nothing Horton fan clutch kicked in.

Transmissions and driving axles are a different story however.....

I sure would like a 15 or 18 quart dump in my truck!

I am honesty surprised Cummins hasn't figure out how to get a bigger pan for the Ram application. The truck is making more power with less oil than its commercial counterpart and potentially with a higher GCWR.

 

[AH64ID]

Yes, the small sump may influence that. A rear gear train 6.7 Cummins in a Freightliner M2 holds around 20 quarts instead of 12.

I was amazed after driving my first big rig with an oil temp gauge. I had always thought oil temps would be high similar to an automatic transmission but day after day the coolant and oil temps would run about the same. They would climb together going up a grade and then drop together when the all or nothing Horton fan clutch kicked in.

Transmissions and driving axles are a different story however.....

I sure would like a 15 or 18 quart sump in my truck!

I am honesty surprised Cummins hasn't figure out how to get a bigger pan for the Ram application. The truck is making more power with less oil than its commercial counterpart and potentially with a higher GCWR.

 

[Alphonse]

Only 1 sensor is listed. Cummins uses that same sensor for oil, coolant and fuel temps for various application. If your truck had the oil temp functionality I believe that there would be a call out for 2 sensors instead of 1.

I did find where the newer Cummins harness (used on many engine applications, not just ours alone) has a spare plug to add an oil temp sender but that would not work in our CTD applications.

So it's a guess or an algorithm, maybe a combo of both......

Thanks, appreciate you taking the time to look up the VIN specific info and give feedback.

 

[sag2]

Although a bigger sump and an oil temp sensor might be nice to have, it just isn't necessary in our application. Oil related engine failures are more rare than ECM failures. So although it might give you one more thing to worry over, just drive it knowing it will outlast anything else available on the road.
I have noted before my Hemi oil temps run up to 280 in the summer pulling the trailer on a good long pull. It does have a sensor and an oil cooler too. The Diesel cooling system is far more robust than the 1500 truck, so actual or not I'm confidant they run just as cool as the fake indicator says they do.

 

[AH64ID]

Watching oil pressure I can attest to the fact that oil heats up much faster and more than coolant in our application, and that's on my 05 with a larger cooling system and 2qts of additional oil.

I am not sure how much hotter it gets but pressure drops on long hard pulls faster than coolant heats up, and continues to slowly drop even with stable coolant temps. Pressure will go from 55 to 40-45 at 2000ish rpms.

However, like you said oil related failures are not common.

280° is hot for conventional oil. I wonder if the hemi will pull power of it gets too hot?

 

[sag2]

280° is hot for conventional oil. I wonder if the hemi will pull power of it gets too hot?

I have never experienced it and have about 7,000 towing miles mostly in summer heat and mountains. Also have had Mobil 1 in it since 800 miles.

 

[Newsa]

Pressure will go from 55 to 40-45 at 2000ish rpms.

What would cause this? Surely not a bypass valve?

 

[AH64ID]

What would cause this? Surely not a bypass valve?

Oil temperature. It's the same reason oil pressure is above 80 on a cold motor at the same rpms.

There is a bypass valve near the filter head but it's more of a cold oil pressure relief valve that opens at 75 psig, which is why only COLD oil will exceed 80 psi.

There is also a plugged filter bypass valve that bypasses the oil filter at 50 psid.

 

[Newsa]

Oh, I guess I haven't had my engine get that hot to notice such a pressure drop. Or maybe my fake oil pressure gauge doesn't show it?

 

[woody72]

I noticed that one was running the winter cover, I assume to increase the coolant and oil temp. A winter cover came with my 15 truck, so when do I install it? I have owned 3500s since 94 and never used a cover, but understand these new models are to run hotter.

 

[AH64ID]

Oh, I guess I haven't had my engine get that hot to notice such a pressure drop. Or maybe my fake oil pressure gauge doesn't show it?

The fake gauge doesn't show it on my 05, so I doubt it would on yours. The main reason for the fake gauge is customers didn't understand the big changes with small rpms and load that diesels experience and it generated too many warranty calls for normal operation.

I noticed that one was running the winter cover, I assume to increase the coolant and oil temp. A winter cover came with my 15 truck, so when do I install it? I have owned 3500s since 94 and never used a cover, but understand these new models are to run hotter.

The new trucks prefer a winter front just like your 94 would have. The efficiency and cooling size of a diesel make them run cold in the winter, and make them take a long time to warm up. The winter front helps them warm up faster and stay warmer. I run mine when the average temp is down below 40 and will stay there for a while. The number of flaps I leave open depends on ambient temp. If I am not towing it will get fully closed off by about 10-15°. I haven't installed mine yet this year and I can tell.

 

[CWade]

I will not get into the discussion on the accuracy of the gauges, but the rule of thumb we have always used in the shop of the Freightliner dealership I have worked in for the past 38 years is that engine oil temperature is normally about 20 degrees F warmer than the coolant temperature.

 

[Gumby79]

Is the oil flow through the filter head the same as the 1st gen?
If so,then reading the oil temp at the tap on the filter head would show the temp after cooling/heating. .
In my mind putting an oil temp in my filter head would only show when the oil cooler is overwhelmed. (Needs more surface area to dissipate the heat) 20-50° above 200° coolent =250-350° in the pan. And a false indication of steady oil temp. (Looking for a more realistic place for my probe)