Oil Cooler Thermostat Replacement

[mach4]

Since I installed a set of engine instrumentation sensors on my car (Engine Instrumentation Project) I noticed that I rarely get above 150 degrees oil temperature, and never above 180. Since the oil cooler thermostat in the oil filter housing is set to open at around 200 degrees it would appear that my thermostat is stuck open. Corroborating this observation is the fact that the temperature rises gradually and not all at once as would be expected when the thermostat opens.

So anticipating the need to replace the thermostat I tore apart my original filter housing (I had to take off the OM617 filter from the 123 chassis and replace it with one from a 126 chassis to get steering gear clearance which is why I had a spare one floating around)

Other than taking the filter housing off the engine, it's a pretty simple and straightforward task.

The first step is to take off the valve seat ring. To do so I just used a stout needle nosed pliers and a crescent wrench.



With the ring removed the spring retainer, spring, return flow locking valve and its spring come right out.



Then the thermostat and its spring seat slide right out.



Here's the parts, laid out in order, for the thermostat assembly.



So sometime soon, I'll take the car off the road for a series of maintenance projects and pull the oil filter housing with the bad thermostat and swap in the thermostat from my "spare" housing.

I didn't see a whole lot of documentation on R&R of the thermostat, so hopefully this will be helpful for those contemplating this procedure in the future.