Hopefully heres is a quick simple question. My 1990 300CE (104 motor) has a small problem. When it sits over night, the oil filter housing keeps draining the oil back to the sump, so on each cold start the oil pressure takes a few moments longer to come up. I know that there a 2 drain valves in the housing. The first opens when I begin to remove the oil filter. The second opens under oil pressure (engine running) and the closes when the engine shuts off preventing the from draining back into the sump. My questions is, are these valves serviceable, or do I need to replace the whole fitler housing as an assembly.

I hope that I explained this clearly enough....