Split case motor oil pumps

schrader7032 · Post by **schrader7032** » Mon Jun 18, 2007 7:10 am

Darryl -

Is it just a matter of RPM? You were turning things by hand at a low RPM, maybe 30-40? Seems like you'd get more volume/pressure when it's turning at 50-100 times faster than that.

Kurt in S.A.

Darryl.Richman · Post by **Darryl.Richman** » Mon Jun 18, 2007 9:31 am

It's hard for me to say what the equivalent would be. Because it is geared down so much, I think I can twist the quill shaft by hand at a rate that is possibly somewhere in the neighborhood of idle speed. Of course, even this is only for part of a turn, so the pressure and volume would only breifly match what would be present in a running engine.

Bruce Frey · Post by **Bruce Frey** » Tue Jun 19, 2007 4:33 am

Is it like the R12 oil pump? The oil pumps for the R12, R5 and R6 are similar in design. I think as long as the parts are not damaged they are quite bulletproof. What you describe sounds normal to me.

I always use a liberal amount of assembly lube when putting an angine together.

My normal starting drill is to kick it through 4 or 5 times to get some oil flowing...maybe a few more kicks are in order.

Good luck,

Bruce

Darryl.Richman · Post by **Darryl.Richman** » Tue Jun 19, 2007 9:04 am

Thanks for the feedback, Bruce. I believe all the split case motors have exactly the same oil pump. I agree that it looks pretty bullet proof, and I also have been using a lot of assembly lube.

My only previous experience is with the /3 and /2 motors, which have a gear pump in a different location but which seem to put out more oil, or perheps the same amount of oil under more pressure.

VBMWMO · Post by **VBMWMO** » Mon Feb 15, 2010 2:51 pm

I've finally got all the parts I think I need to put my 1928 R52 motor back together again. The mag is rebuilt and turns over nicely, and what's more important, I can see a strong spark even when I turn the gear by hand. The nice folks at BMZ had all the pieces I needed.

I assembled the bottom end of the motor by carefully fitting the crank into the case half, being certain to align the bearing housings over the oil gallery ports. I put the crank at TDC, then I set the cam so that the marked two adjacent teeth were in mesh with the (new, nylon) idler gear. Then I assembled the case halves.

Of course, at this point I thought of checking the oil pump. So I put some oil into the case and I installed the quill shaft. I turned the crank over a number of times (didn't count, maybe 20 or so times), but didn't see much evidence of oil. I hadn't realized how slowly the oil pump runs in comparision to the crank RPMs, but as it's run off the cam (half speed of the crank) and it's a worm gear, it looks like it goes at maybe 1/8th crank speed.

Anyway, this got me worried, so I disassembled the crankcase again and pulled out the crank. Then I spun the quill shaft by hand. Oil bubbled out of the two main bearing ports and also the tube that leads up to left side of the timing gear train.

Then I reset the crank in the lower case half and turned it over a lot of times, pausing occasionally to spin the quill shaft -- I've only got two hands, ya know -- and after a surprisingly long time oil did start to come out from around the conrod big ends.

So, feeling that there was oil where I needed it, I reassembled the crankcase and timed the motor while installing the magneto (this has been covered in another thread).

I am very glad I went through this exercise. I would hate to start up a clean motor, even with a few kicks before letting it fire up. It took a few dozen crank rotations for me to be sure there was oil everywhere.

Should my oil pump put out more flow than this? (I was careful in cleaning it and reassembling it, and everything seemed to be in good condition. I also was very careful to clean out the oil galleries.)