I recently changed my oil ('81 240D with 180k) but was too lazy to fill the oil filter with oil on the startup. There was about 15-20sec of no oil pressure on startup, then everything was fine.

Sometime after, whether due to this or not, I'm noticing a periodic, squeak coming from the engine bay that I haven't been able to pinpoint. It appears most prominently at low rpm and dissappears off-idle and then completely once the engine is warm.

Any suggestions where to look?

Have I scuffed a journal bearing saving 2 minutes of work?

As far as i know (which may not be much), the oil always runs back into the pan anyway. That is why the oil filter container is not full when you open it. It has thick oil residue on the filter but it is not swimming in it. I don't really know for sure but I think if you tried to put oil in the filter housing, it would run back into the pan. When I have had the oil changed, it usually gets filled up right away so I assume that the residual oil can carry the motor for the 30 seconds it takes while the oil pressure builds up. I certainly never rev the motor until it has adequate oil pressure.
I hope you find the "crickets." Sometimes the new oil will change the sound of the motor a little anyway. It's probably something else...I hope!

My 2 cents

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1982 300D Turbo "Helga"
380,000 miles

Ditto what Mr. Watson mentioned. I am certain no harm was done to your car---I have always changed mine the way you mentioned. The residual oil will certainly be adequate until pressure builds. Machen Sie bitte keine Sorge. (Don't worry)

I should have also mentioned that many engine makers have their oil filters oriented upside down and sideways---no way to pre-fill them that way. Just ask me about my Perkins diesel in my boat.

And...in reality, you could probably drive to Panama with no oil and not score the bearings, not that I recommend this but they are more rugged than you think.

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1982 300D Turbo "Helga"
380,000 miles

"Crickets" in the engine compartment is almost always caused by loose/slipping fanbelts. This could be completely unrelated to your changing the oil, or possibly you got some oil on the belts when you were changing the oil.

Additionally, I didn't even know you were supposed to fill the filter with oil, so I don't, and I never had a problem. How can you fill the filter with oil? Won't the oil just drain right back into the oilpan if you pour it in the filter housing?

Greg
'84 300D

I tightened the belts a couple of days ago to no avail, but just started it and sprayed some belt dressing on it and it went right away.

I've never heard make such a metallic sounding noise...

Many cases of "rod knock" have been cured by lightly sanding a belt. This is particularly true, for unknown reasons, no Buick V6s. Sounds JUST like a rod clanking, disappears instantly as soon as the slick spot in the belt is gone.

Buy new belts -- if they squeak they are shot, and they don't cost that much. Don't overtighten, please, it ruins water pumps and alternator bearings. If you can push the belt down 1/2 inch with firm thumb pressure between the pulleys, you're fine. If it squeals or thumps, something is wrong. A/C belts may need to be a bit tighter to keep them from thrumming.

Don't use a prybar on MB V8 PS/water pump belts unless you want to put a new water pump in!

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!