Has anyone ever had to - or heard of needing to - prime the oil pump after an extended 'dry period' to get oil pressure? The situation is a 100k+ mile 928 having sat for several weeks with no oil in the sump during a pan gasket and MM R&R. The theory is that the pump apparently got so dry that it could not pull a vacuum, but with some priming, oil pressure returned.

And if so, what - if anything - might such an occurrence indicate?

 

A worn pump.

 

Eating into my 3rd week awaiting parts with a dry sump (pan gasket R&R), my plan was to simply fill the sump, pull the fuel pump relay and ground the coil wire (16v): then, run the starter over a bit before installing plugs to 'oil' the engine. I'm sure the pump will pick up flow and pressure.

 

After my rebuild the engine had been cranked over by hand a few times doing the timing belt tension and cam timing. After that I did as you plan to, disabled ignition and fuel and then cranked with starter.

That is way good enough to 'prime' the pump, you should see oil pressure with the starter.

Then just start her up, as your engine has been sitting it will sound like a diesel as the hydraulic lifters take while to fill with oil.

Chris

 

After my top end repair I tried to get a drill to spin the oil pump, but there wasn't enough room as I'd left the radiator in. Instead I simply spun it by hand, it was very obvious when the pressure built up, and since I hadn't replaced the cam covers at this point, I could see oil flowing around the lifters.

As Chris said it takes a while for the lifters to fill properly when it's running, and the noise was enough to make me think I had completely trashed the engine and wasted three months trying to repair it.