Oil Cooler Problems
 

I've got an '84 300D with oil cooler problems, oil does not seem to be circulating through it, even after running at high speed for a long while. The oil cooler never gets warm, nor the lines, so I suspect that the thermostat wasn't openning at the right temp, so I replaced it but it still doesn't get oil circulating through it. If anyone has any idea on what is happening or had first hand experience with this sort of problem your help would be greatly appreciated. EWG

You would have to be abusing the engine to get the oil that hot in most cases. The oil cooler is there as an emergency type cooler, not for every day use.

Sounds like the thermostaticaly controlled oil cooler by pass slide that is located in the oil filter housing is either stuck or being held in bypass position. Oil should circulate through the oil cooler when the engine warms oil after running a few minutes.

Rob