Oil presure issue M189 engine

[autocomman]

So I know the M189 may not have come in a Pagoda, but there are so many knowledegable people here I thought Id ask.  At our shop we have a 1960 300d with the M189.  Bought 5ish years ago and it was a nice car, drove very well, ran great.  Parked in out showroom,temerature controlled etc etc, fuel drained from the tank it sat there for the next 5 years.  Pulled it out the other day, filled the tank, fired right up which I didnt expect haha....but no oil pressure.  Checked the mech gauge, removed a pressure switch to install another gauge to verify, no pressure.  Took the rubber line off from the block that feeds the tee where the pressure switch is and its clear, not swollen or plugged.  The engine was run for maybe a minute.  Ive had some other old engines that can take a whle to build pressure after an oil change, but I didnt chage the oil in this one...oil was decent enough and full, so we fired it up to go from there.

So, is it possible it lost its prime from just sitting?  Anything I can check or common things that may cause this from just sitting?  If all looks good does the pump drop off if I remove the lower sump and not the whole pan so I can try and reprime the system?  Is there an easy way to reprime the system?  Doesnt look like there is an easy way to just spin the pump.  I assume this motor is similar enough to the M100 and others of the time that someone may have some advice.

I know with lots of pumps if they are drained they have to be filled with oil before they will pump again...

Mark

[scoot]

I have a car with an M189  (1965 300SE LWB sedan) and it had sat for maybe 10 - 15 years.  After changing all the fluids, etc I cranked the car and while it didn't start, the oil pressure did build it.  I didn't do anything to "prime" it, nor have I heard of having to do that. 

(after cleaning the fuel system extensively I can now start the car)

[Benz Dr.]

Never run an engine without oil pressure! 

The 189 engine is nothing like a 113 engine and it has a completely different set up. I rebuilt one several years ago and it was both interesting and challenging at the same time. I remember having low oil pressure and then it reduced to almost nothing as the engine warmed up. After removing the engine from the car ( 112 RHD sedan ) I found that the oil pump was held in place by two hex socket screws and not one like you would find on our cars. The missing screw left a gap large enough for a lot of oil pressure to escape.

The oil pump on this engine has a rather long neck on it but it should draw oil quickly. This pump runs on the same shaft or system that runs the distributor drive so clearly that must be turning or the engine wouldn't start. Sounds like it could be the oil pump, plugged screen on the pump, or something in the drive system that runs the pump. This probably won't be a simple fix. 

I always spin an engine over without spark plugs installed until I see the oil pressure gauge move. 

[ja17]

Yes, I think Dan could be correct. If sludge settled in the oil pan during storage, then the fresh oil change may have loosened the sludge, which could moved and plugged the screen. Remove the oil drain plug again and inspect the inside of the oil pan and pump with a scope.

[autocomman]

Thing is I didnt change the oil, its what was in there.  I was gonna remove the oil pressure switch from the tee and put a vacuum bleeder on there, see if it would suck up oil...theoretically it should draw from pan and fill the lower galley, pump and filter.  I would assume the filter is right after the pump in the flow.  If I dont get any oil doing that, then drain it, and inspect or just remove the lower sump.

[Benz Dr.]

I'm not sure if that engine has a lower oil pan. If it does then you will be able to look at the screen.