No oil pressure

[Gunny]

We recently rebuilt my buddies MB engine, now it has no oil pressure. Anybody have a clue what could have gone wrong?

[Chuck Lutz]

1) not enough oil in the sump
2) pickup is flipped UP and not sitting on the oil in the sump
3) pickup tube is leaking or gasket where it fits to the block is leaking/loose/missing
4) pickup was dismantled and thoroughly CLEANED and is plugged up
5) oil pump was not "primed" prior to installation

Those are the first problems to check out....you did not mention if the oil pump previously worked CORRECTLY or if it was "overhauled" during the rebuild.

[Scoutpilot]

Is it a rebuilt pump?

[Gunny]

The oil pump was working prior to the rebuild. A new pump was installed after the rebuild, when we got no oil pressure after running it a little while, we replaced it with the old oil pump, still no pressure.

[Joe Gopan]

Was it a gear drive or chain drive? A couple things come to mind, oil galley plugs, or if it is a gear drive, the oil spray nozzle may not have been installed.

[Greendot319]

Did you prime both pumps prior to running them? If the new oil pump was not primed and the old one was not primed before re-installation then you will not got any oil pressure.
Matt

[Chuck Lutz]

See #5 above....