I mentioned this one other time, but it was back in Jan. After traveling on the highway, doing 75 mph, the oil cooler is just that, cool. On my SD it would be hot to the touch, but this one is luke warm at best and that's probably due to it's proximity to the radiator. Is it possible for the temp. sensor in the oil filter housing to go bad. Also, is there any harm in running her as is?

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

I wouldn't think the oil cooler was bad, highly unlikely. It is a passive device, unless it is clogged ?. You might pull it on your next oil ghange and take it to a radiator shop to be checked.

The thermostat routing oil to the cooler begins to open at 95-99 C or 203-210 F and fully open at 110-114 C or 230-237 F. M-B has a special tool called a telethermometer to sense the oil temp. that is inserted into the oil dipstick tube (read $$$ tool).

I see that you live in NJ, where the ambient outside temps have been low because it is winter (or was and temps are still relatively low, esp. compared to summer temps). It may be that your engine is not getting hot enough to heat the oil enough to open the thermostat or it is opening only a bit. This may be the reason why the oil cooler is not getting warm/hot. I've seen the same results with other oil coolers using thermostats to control oil flow to the cooler - in the winter or low temps the oil does not flow to the oil cooler. However, if later this year when outside temps. rise and the oil cooler is not getting warm/hot (esp. on hot days and/or driving conditions where the engine gets hot) then I would look for a problem. Also, oil needs to be hot to be effective, say 180-190 F minimum.

Good Luck!

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1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
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Well, the temps have been in the 60's lately, so I figured the ol would start to heat up as well. Though this engine does run much cooler than my SDs., so that could be the difference. I guess I'll wait and see what the summer temps do for it.

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member