Oil pump prime?

[Erik Jenkinson]

So my M1009 has been sitting without oil in it for about 6 weeks, I replaced the rear main seal, the oil pump, and added some Leroy diesel oil cooler lines. Is it necessary to prime the oil pump before restarting? I have heard mixed opinions. Some don't appear to do it, others just remove the vacuum pump, and turn the oil pump with a drill. Still others pull the pink wire from the injection pump, and just crank the engine. Leroy diesel even makes a priming tool. What is correct? This is by no means a new engine or anything, I just want to know what is sensible.

 

[Barrman]

The oil flows from the pan to the pump, filter, oil cooler lines and then the crankshaft bearings. Since you have added the dry oil cooler and lines. I think it would be a good idea to prime the system before you start it. A regular 8mm socket will fit the oil pump drive shaft. A 1/4" socket extension will fit most any drill and let you turn the pump until the oil shoots out onto the spinning socket. You will actually hear and feel the drill take the load of moving the oil right away. If you don't, then you have to reverse the drill direction and try again.

 

[Sharecropper]

Cranking any engine without oil pressure is probably the worse thing you could do. The bearing clearances are designed to operate while being flooded with pressurized oil from the oil pump. If you have installed a new oil pump, obviously the pump has no oil in it, and the galleys and oil passages have very little oil in them. If you crank the engine in that situation, it will take a few seconds for the new pump to prime and fill and then fill the galleys and passages. During those few seconds the bearing surfaces will be operating under stress without lubrication. So don't do it. Leroy offers a primer device specifically for this purpose. If you can spare the change, purchase the thing from Leroy and use it immediately prior to cranking. Simply remove the vacuum pump and insert the primer device, spin it with a drill for several seconds or longer until you have ample oil pressure. Then remove the primer device and replace the vacuum pump. Easy peasy.