That's a non-turbo engine, the oil pump is shaft driven of the IP drive and the oil pump is held in place by two bolts. Should be accessable after just removing the lower sheetmetal oil pan IIRC.

Ditch the Fram oil filter, they are junk. Get a Wix, Mann, or Knecht. Wix is usually available at better autoparts chain stores and is a excellent filter. More expensive, but you are getting what you pay for.

As a said before, have a care while inserting the oil filter in the canister, there is a seal half way up (between the full flow section at the bottom and the bypass filter at the top) that can get unseated, allowing oil to bleed past the seal back into the pan.

Unless you missed on the bearing sizes (crank ground to the first undersize, for instance, and you didn't know it) you should be fine there. Did you mic the crank? It could be worn badly enough to cause low oil pressure, but I suspect you would have seen that. MB uses enough babbit on those bearing you really have to work to damage the crank (lock the engine up from no oil, for instance).

Oil clearance on new bearings should be on the small side of 1-3 thousandths. More and you will have low oil pressure.

The relief valve is in the cansiter assembly, along with the various oil channels and the oil cooler thermostat.

Do use a known good mechanical gauge, it may just be a tired dash gauge!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!