Engine temp with very high ambient

[Thump]

Curious what others are seeing for engine temps as the heat is upon us, again (well, except Lake Tahoe who got snow over the weekend).
Running empty on my 2011 CC Laramie DRW 4X4 up ~4 mile probably 2-3% grade with AC going and outside temp reading 117° (sun to my tail, if that matters) I hit 216° engine and 175 trans. IAT was topping out around 180. CACT was ~135.

Just seems it shouldn't be getting that warm unloaded. Truck has 130K on the clicker. I won't say hot, because that's not hot. It is higher than my 5.9 HPCR version ever ran.
What say you, folks? What are you guys seeing? I searched around here and didn't see a good topic on hot temps and 4th gens.

 

[apgambino]

Highest i saw on my 2015 3500 SRW towing my 16k fifth wheel up a decent grade on CA-14 (Santa Clarita to Palmdale if it matters) in 95 degree heat was 235ish, with the a.c. on. That is until the fan clutch engaged and dropped it rapidly. I've seen mine get around 200 unloaded when it's stupid hot; I wouldn't worry.

2015 3500 SRW 4x4 MegaCab Laramie Aisin

 

[Berrigan]

Curious what others are seeing for engine temps as the heat is upon us, again (well, except Lake Tahoe who got snow over the weekend).
Running empty on my 2011 CC Laramie DRW 4X4 up ~4 mile probably 2-3% grade with AC going and outside temp reading 117° (sun to my tail, if that matters) I hit 216° engine and 175 trans. IAT was topping out around 180. CACT was ~135.

Just seems it shouldn't be getting that warm unloaded. Truck has 130K on the clicker. I won't say hot, because that's not hot. It is higher than my 5.9 HPCR version ever ran.
What say you, folks? What are you guys seeing? I searched around here and didn't see a good topic on hot temps and 4th gens.

Yesterday driving from Scottsdale to Mesa, 20 miles. Solo, not towing, on city streets. Outside temp showed 120. Engine temp was 190, oil was 205, trans was 185.

 

[AH64ID]

Stock thermostats are 200° for 2011 which means they don't go full open until around 217-218°, so those temps seem normal for the ambient temp you were seeing.

The 5.9 HPCR's used a 190° thermostat and didn't have a EGR cooler so it's hard to compare them. The cooling system on the 6.7 is also smaller.

In 2013 the thermostats went back down to 190° so it's hard to compare to a 13+.

 

[AH64ID]

Highest i saw on my 2015 3500 SRW towing my 16k fifth wheel up a decent grade on CA-14 (Santa Clarita to Palmdale if it matters) in 95 degree heat was 235ish, with the a.c. on. That is until the fan clutch engaged and dropped it rapidly. I've seen mine get around 200 unloaded when it's stupid hot; I wouldn't worry.

2015 3500 SRW 4x4 MegaCab Laramie Aisin

That seem's too hot for a 190° thermostat. 225° is the max allowable temp for the 190° thermostat from Cummins... or did Ram switch back to a 200° thermostat in 2015?? Even with a 200° thermostat 235° is right at the max allowable temp and seem's too hot.

 

[kthaxton]

That seem's too hot for a 190° thermostat. 225° is the max allowable temp for the 190° thermostat from Cummins... or did Ram switch back to a 200° thermostat in 2015?? Even with a 200° thermostat 235° is right at the max allowable temp and seem's too hot.

What do you mean by "max allowable temp for a thermostat"?
Once the temp is beyond its rating....it doesn't control or allow anything, it stays open and the efficiency of the entire cooling system is all that controls (or attempts to control) the operating temps. At this point the rating of the stat means nothing.

 

[AH64ID]

Cummins has numbers for the max allowable engine temp for each thermostat. For example the 190° thermostat cracks at 190°±3°, goes full open at 207°, and has a max allowable temp of 225°. Basically at 225° the cooling system is being worked beyond it's capabilities.

So the rating of the thermostat does have a say on the max allowable temp. The engine may be able to handle more heat in some areas but the heat rejection capabilities have been exceeded.

 

[kthaxton]

So the rating of the thermostat does have a say on the max allowable temp. The engine may be able to handle more heat in some areas but the heat rejection capabilities have been exceeded.

I'm still not following you. Whether it is a 190º or a 200º or whatever, both of those would be fully open at 225 and would have no influence on temps nor would either care (but the rest of the system might!)......what I am getting at is I have never heard of a t-stat itself, having a maximum temp range, because once it is open (near its rating) it can't do anything else. I can understand the cooling system having a theoretical max, but the stat just has no influence on anything once it is open. It is a minimum temperature controller, not a max. .

 

[AH64ID]

I'm still not following you. Whether it is a 190º or a 200º or whatever, both of those would be fully open at 225 and would have no influence on temps nor would either care (but the rest of the system might!)......what I am getting at is I have never heard of a t-stat itself, having a maximum temp range, because once it is open (near its rating) it can't do anything else. I can understand the cooling system having a theoretical max, but the stat just has no influence on anything once it is open. It is a minimum temperature controller, not a max. .

Don't think about it as a function of the thermostat but rather with a 190° thermostat installed the max allowable temp is 225°. With a 180° thermostat installed the max allowable temp is 212° and IIRC the 200° thermostat equipped engine has a max allowable temp of 235°.

I'm just relaying information I received from Cummins on operating temperatures and thermostats.

 

[kthaxton]

Ok, so what you are saying is that if the engine came from the factory with a 190º stat, the engine's maximum allowable (or "safe) limit is 225º, and if it came with a 200, its 235 etc?
If so, this makes more sense. The way you worded it seemed like you were saying the t-stat somehow had control over the engines maximum temps even though it was fully open.

 

[AH64ID]

Ok, so what you are saying is that if the engine came from the factory with a 190º stat, the engine's maximum allowable (or "safe) limit is 225º, and if it came with a 200, its 235 etc?
If so, this makes more sense. The way you worded it seemed like you were saying the t-stat somehow had control over the engines maximum temps even though it was fully open.

Yeah... the thermostat can't control it but the thermostat dictates the max allowable temp.

 

[bigceltic]

That seem's too hot for a 190° thermostat. 225° is the max allowable temp for the 190° thermostat from Cummins... or did Ram switch back to a 200° thermostat in 2015?? Even with a 200° thermostat 235° is right at the max allowable temp and seem's too hot.

Last week I was towing up Monarch Pass (11,312 feet) and was getting up to 210-215 by the time I got to the top (ambient was around 75) - came right back down on the downhill. Trans hit 200-203 (was in 2nd most of the way up but I don't think my TC was locked) - it came back down to 180 on the downhill.

 

[AH64ID]

Last week I was towing up Monarch Pass (11,312 feet) and was getting up to 210-215 by the time I got to the top (ambient was around 75) - came right back down on the downhill. Trans hit 200-203 (was in 2nd most of the way up but I don't think my TC was locked) - it came back down to 180 on the downhill.

Sounds right. Before I reprogrammed my fan with UDC pro I would pull most hills at 213-215°. With the reprogram I rarely hit 209° before it cools back down to 206°.

 

[Thump]

Yesterday driving from Scottsdale to Mesa, 20 miles. Solo, not towing, on city streets. Outside temp showed 120. Engine temp was 190, oil was 205, trans was 185.

The area I'm talking about was Loop 202 Red Mtn eastbound as it turns south between Higley and Power.
Wathing it the last few days it has gotten up as high as 218. With the 200° tstat, I'm not going to worry too much. It is a little disconcerting as the truck is empty with those temps, but oh well.

 

[RustyJC]

I saw 230 degF briefly at the east entrance to the Eisenhower tunnel on I-70 eastbound (11,100 ft elevation) towing our 19,000 lb GVWR 5th wheel last month in the truck in my signature. No lights or alarm chimes.

Rusty