I just bought a 1977 240D with bad auto trans. I watched it set at a garage all summer, and finally stopped to see if it was for sale. Before I tear the trans out, I wanted to check the engine. It started up with no trouble, and sounds good, but the oil pressure pegs out at all times, even after warmed up. (peg is at 45 psi). I drained oil and put in some lighter weight (its cold here in Nebraska!), but that did not help. I hooked up a different oil pressure gauge, and it shows 70 psi at idle, and maxs out over 90 psi when I rev up. I took the sump pan off, and it was nice and clean, no loose metal. Also cut open the filter, no metal there.

I have a '76 240D that was ran out of oil, and it did same thing. It is on the engine stand now being torn down. Lots of metal in bottom of that pan.

I read some posts regarding 240D oil pressure, and it seems they might 'peg' the oil gauge a lot. This new 240D has 118k miles (at least), should I tear down and inspect, or look for faulty pressure regulator on oil pump? Or is there something else I am missing?

Thanks for any help!