It can be done, but is tough. I have done this by loosening the engine mount bolts and using a screw jack to lift the engine high enough to pull the pan. The pan has to come off before the front cover.
Yes the oil pump does have a screen, but if a piece of the rail pin falls in, it will eat through the screen and kill the engine. Ask me how I know. I have had this happen to my car before I knew the insides.
1992 500E (very soon I hope
1981 280GE SWB
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MERCEDES SPECIALIST 8 YRS
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