Testing/Cleaning Oil Cooler Thermostat

[JoeIsuzu]

The C223 has an oil cooler in the base of the oil filter bracket. It uses engine coolant to regulate the oil temperature. In the hose just above it, there is a thermostat, designed to open only after the engine is warm. I'm told that this can clog, and thus contribute to engine cooling issues. I was not sure if my oil cooler thermostat was opening, so I tested it. Unless you are the absolute MASTER of the kitchen, don't get caught doing this!

First, I verified it was closed. It did not allow water to pass through when cold. Then, I put it into a pot of boiling water. I dipped it, attempting to catch water in it. It drained out quickly. I did not test for the opening temperature, but I was able to verify that it DOES open.

Lots of sludge boiled out, so I'm assuming this was also a cleaning.

P.S.: I'm washing that pot THOROUGHLY, by hand and in the dishwasher. Antifreeze is very poisonous.

This is the oil cooler thermostat. It is installed in the line from the oil cooler to the heater hose loop.

I could not get the thermostat to hold water once it got hot. That's good.

Jack

[puttputtinpup]

I remember one of the guys also flushing out the cooler itself of the muck & crudd by soaking it 1st with "something", then flushing with water. I'm not sure what they used, but they claimed it helped in the circulation of coolant through there. CLR, vinegar, rad. flush..not sure what it was.
Before I learned what that inline thermostat was, I thought it was a check valve of some kind. I tested mine like you did, except I attached a long piece of scrap heater hose to one end, and blew through it to see if the thermostat opened, or whatever.
Jerry Lemond has stated before that it wouldn't hurt to just remove this cooler thermostat, if it didn't work.