Temp loss through oil pan using IR thermometer

[mmosberg]

I have a Yanmar 6LY 440 hp marine diesel engine. It is a 6 cylinder in line common rail with a displacement of 5.2 ltr. Max rpm is 3300. It is filled with 19 ltrs of Mobil Delvac MX 15w-40.

I noticed that after longer periods of cruising at 70-75% load with a corresponding rpm of abt 2800 that if reducing to idle (600 rpm) the oil pressure drops to 1.4 bar before gradually increasing ro about 2 bar as the oil cools down. The cooling water temp remains stable at 74-75 deg C no matter how hard I run it. So I measured the surface temp of the oil pan with an IR thermometer while at 75% load and measured 103-105 deg C.

Question: Does anyone have experience with how much heat is lost when measuring this way? I am a little concerned about the oil temperature and wonders if I maybe should start using the synthetic Mobil Delvac for possible better temperature abilities.

Regards from Norway

 

[Kira]

I just read a good thread on measuring temperatures of oil pans with an infrared thermometer.
Like you, the concern was accuracy. I looked but I cannot find the thread.
AS I RECALL the steel pans were representative of the fluids' temps.
However, cast (aluminum) cases can draw heat away and give false low readings.
Sorry I can't deliver my source.

If I were you, I'd consider just switching to a synthetic because synthetics handle heat better.
Your 105c reading is well within conventional oils' working range....but I'd still go with a synthetic.
Hej

 

[redbone3]

It is problematic to measure with an IR thermometer. It wouldn't be difficult to rig a thermocouple that would go down the dipstick and give real oil temperatures. Both thermocouples and thermocouple meters are fairly inexpensive. See this video:

 

[Snagglefoot]

The 1.5 bar is 22 psi for our American friends. A bit low, but not all that bad. The accuracy of the oil pressure gage might be in question as well. How many hours on the engine?

 

[Imp4]

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[BigCahuna]

It might help if you posted the age of the motor, how many hours are on it, and when was the last service if known. From what you've posted 75c is only 167 f, which doesn't sound too hot for the motor. If the motor was running hotter then what the book calls for , you would want to investigate the thermostat, water pumps or belts. As far as oil pan cooling, being the motor isn't exposed to the same airflow as a car would be, I doubt that would be an issue in the confined space of a boat. Don't forget when the motor is running at 2800 rpms under load, there's alot of heat being generated. Air temp and water temp effects the motors internal temps. Don't know if this boat is new to you or you've had it a while, but if it runs consistently the same, it's more then likely normal.,,,

 

[mmosberg]

It might help if you posted the age of the motor, how many hours are on it, and when was the last service if known. From what you've posted 75c is only 167 f, which doesn't sound too hot for the motor. If the motor was running hotter then what the book calls for , you would want to investigate the thermostat, water pumps or belts. As far as oil pan cooling, being the motor isn't exposed to the same airflow as a car would be, I doubt that would be an issue in the confined space of a boat. Don't forget when the motor is running at 2800 rpms under load, there's alot of heat being generated. Air temp and water temp effects the motors internal temps. Don't know if this boat is new to you or you've had it a while, but if it runs consistently the same, it's more then likely normal.,,,

The engine is MY2020 and has about 180 running hours, and the oil was changed at 150 hrs. The coolant temp of 75 C is the correct temp according to Yanmar. Yanmar marine are known for their low (set) coolant temp compared to other manufacturers.