Diesel temp normal but engine too cool? - PeachParts Mercedes-Benz Forum

JHZR2 · #1 01-11-2004, 07:06 PM

Hi,

I have had a number of odd phenomena, which really showed themselves this weekend on my trip from near NYC to Pittcburgh (had great seats for a penguins game)

Start a month back... I was tinkering under the hood, and opened the coolant reservoir cap. for whatever stupid reason, I didnt reclose the cap, it was just laid on the reservoir. I drove (just about all interstate) for over a week, and temps always were OK and heat worked, etc. Didnt loose a drop of coolant either. (temps outside were neart freezing).

This weekend, driving out to pittsburgh, it was lower than 20 degrees at a rest stop on the PA tpk where I stopped. I popped the hood to look around to see how hot the radiator and oil cooler got in these situations. The radiator was slightly warm, as was the valve cover. Definitely not as warm as usual though. Then I felt the oil cooler. It was absolutely cold! As cold as the sheetmetal of my car!

Driving on the way back, I noted that any change turning the heat up, would result in engine temp dropping... OK, thats fine. However, what I didnt expect was that when I turned it down, the temperature would go from its usual point of 82 up to 86-90. I know this is still OK, but it never does this with the heat on between 22-26 and warmer temperatures outside.

-Is it odd that I could drive 100% fine, and even have normal power and economy with the radiator cap not even slightly screwed on?

-Is it odd that after 200mi at 70+ mph, thje oil cooler is absolutely cold, even if it is 20F or so out?

-Is the fact that my cooling system temperatures are fluctating so in dicate that perhaps my system was cooling too well? Or perhaps that the thermostat isnt working correctly?

I am taking my car in for some suspension service to an MB indy on tuesday. If there is a possibility of something else wrong, Id like to have it looked at as well while Im in, not have something that I might catch early come to kick me when the summer comes... Thats why any help or info from this forum would be really great.
Thanks,

JMH