Oil pump problem.

[GBRAVO]

I have a 1951 Panhead almost 100% Stock and I know that the easy solution to this problem is install a new S&S Oil pump but I would like to keep the original one. Also I know that the Pan has problem with the oil pressure when it get hot.

Well when the engine start cool I have good oil pressure (35 psi) then after 10 minutes when it get hot the pressure goes practically to 0 psi.
I installed new gears, new shaft, and the pump body doesn't look too wear and the problem persist, may be I don't know how look the body wear.... any advise o solution. THANKS.

Maybe its not the pump....

[Cotten]

If your lower end is loose as a goose, or even just the pinion bushing in the cam cover, all of the pressure just spills out into the gearcase, etc..

Remember as well: Pressure and Flow are related, but very independent.
You can have plenty of Flow (that's good) with next to no back Pressure.
On the other hand, you can have 60+ psi on the gauge because the Flow is blocked (that's bad).

The S&S pump is a good unit, but hardly worth bastardizing your stocker with.

When your motor is warm and the light is on (beware that modern sending units require extra poundage to shut off...) open the oiltank filler cap and see if there is a healthy return. That might not eliminate the possibility of diversions within the motor, but at least you will know that the pump puts plenty in,.. and plenty out.

[DuoDave]

When I got my 59 up and running, the original oil pressure switch wasn't working. I fitted a brand new switch and found that, once my engine was fully warmed up, the oil light stayed on unless I was running pretty high revs (over sixty in top). I have a good healthy return to the oil tank and I know that oil is getting everywhere it needs to go, so I am not too worried about it. It just seems to be the way it is with these old motors. V-Twin do most of the parts if you want to rebuild your original oil pump, but it sounds like you probably don't need to.

[GBRAVO]

Cotten, DuoDave, Thanks for your advised, I'll check the oil flow at different temperatures, actually I'm using HD W-60 oil.
The engine lower end look fine to me, I installed new bushing in the cam cover and oil pump shaft.
All my concern started wen I fitted a new oil pressure switch, I experienced the same problems that DouDave describe, now I'm using the old one because the oil light on piss me off.
Thanks again.

[Ente]

And the same goes for me as it did for DuoDave. But as long I could see that the oil was floating around in the engine even if the oil-light was on it seams that everything was OK. The main task for the oil is to lubricate which low-flow will fulfil, hi-flow help the engine to stay a little more cleaner and cooler. So it's my opinion too that it's ok for you.

[VintageTwin]

F.Y.I. don't just remove you oil pump and bolt another one on! The pumps have to free-spun. Means removing the cam cover, pinion gear, spin to test, install new pump, torque to 90-120 in. lbs. and free-spun to check for internal pump gear bind.

[Ente]

That's right !
I forgot to do that on a evo (same construction) before I really know how the oilpump-drivegear in the cam-cone was fitted, the drive-shaft was stucked. Well, I had to remove the cam-cover anyhow to take the retainer away. since I wanted that shaft removed and checked also.

[GBRAVO]

Folks I checked the oil return to the tank as well as the oil return trough the pushrod and the flow is good enough. Thanks again.... This is a great Web Site!

[BigMike]

You may want to use the paper pump gasket vs the plastic one. That will tighten up a worn pump some, and really helps get the pressure up a little higher when hot