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I need some advice. I dont' know if this is just my inexperience with diesels or a potential problem brewing.

I've noticed that once temps hit 80F or more my truck is running at about 210F instead of 185 (this is also the case on the highway with cruise control set at 70 - 2K RPM). The transmission oil temp will clime to the 200F mark, but usually stays closer to the ~ 170 mark (whatever is the normal op temp).

My concerns: Engine is not cooling to it's normal operational temperature even when cruising under no load. The coolant was changed out recently (about 10K - 15K miles / 4 months ago). Coolant levels have been consistant and there is no smell of coolant leaking.

Is it normal for there to be about a 30 degree temp difference between the oil and trans temps? I had read somewhere that the oil and trans temps sould be almost the same and shift consistantly together. If not, what could the problem be?

Thanks for any help.
 

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Are you asking about an intercooler for the turbo Sam? If you are, do you have pyrometers on your exhaust? Also, are you asking about engine oil temp, or engine coolant temp?
As for the trans temps & engine oil temps being the same, mine aren't, but I have an aux trans cooler on it. If yours has the radiator trans cooler, then it may run the same unless you're towing, then your trans temp could run a little hotter.
 

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Discussion Starter #3
Are you asking about an intercooler for the turbo Sam? If you are, do you have pyrometers on your exhaust? Also, are you asking about engine oil temp, or engine coolant temp?
As for the trans temps & engine oil temps being the same, mine aren't, but I have an aux trans cooler on it. If yours has the radiator trans cooler, then it may run the same unless you're towing, then your trans temp could run a little hotter.
I appreciate the reply, Stephan. I was asking about the engine oil temp versus the trans oil temp. I don't have EGT or boost gauges yet, but I need to install some soon. Both temps never get above 210 based on the in-dash gauges, it just concerned me a little the oil temp stays around the 210 level for the majority of the trips even when running with no load.
 

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ok, it's not unusual for your engine oil temp to run as much as 30 degrees higher than the engine coolant temperature that shows on your dash guage, because there is nothing to actually cool the engine oil unless you have an aux oil cooler on it. If you have the in radiator engine oil cooler, it still won't bring it down to the radiator temp. I actually took mine out of the radiator, & mounted it as a stand alone out in the air & got better results by about 10 degrees.
I've seen my engine oil temp as high as 250 deg F when the engine coolant was only at 210 deg F
 
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