Oil Pump Gasket Thickness

[otis71]

I recently built a 60 FL motor and when the oil gets hot the oil pressure drops to where the oil pressure light comes on under around 2000 rpm. Going back to the pump I see nothing wrong. I used James gaskets which are .010 thick, both the cover and the body gaskets. Going through my stash I found some other pump gaskets that measure .005. I’m thinking the James gaskets are too thick. Does anyone know the thickness of oem gaskets? I always thought James gaskets could be relied on.

[larry]

The pressure side gasket should provide minimum side clearance of the gears without binding. .010" is too thick. The return side isn't as critical.

[T. Cotten]

I recently built a 60 FL motor and when the oil gets hot the oil pressure drops to where the oil pressure light comes on under around 2000 rpm. Going back to the pump I see nothing wrong....

Is the sending unit OEM, Otis?

It should 'open' at about 4psi, whereas repops can require two or three times that much.

SENDTEST.jpg

Note also that a Pan can run fine at minimal pressure, as long as there is flow.

....Cotten

[Carl Olsen]

We had the same problem with the thick gaskets, so we had some made and they are .005 and after torquing to 90 inch pounds they crush to .003 like the original brown paper ones from the 40's and 50's. That's what we do at Carl's Cycle Supply, make it right so it is the way it is supposed to be.

Carl

[otis71]

An updated question: just for a try I put a 62-67 pump on which is identical except the idler gears have a bigger shaft diameter and I used a thinner gasket. I don’t really know if pressure improved because as soon as I started it the crankcase filled with oil. The scavenger galley is spotless on this pump, used the same drive gear as before and put nos idler gears in it. This makes no sense. Is there a reason the later pump wouldn’t work? The feed pump idler gear is different in it doesn’t have the part that goes into the crankcase recess but that should not effect the scavenger side.

[T. Cotten]

Is frothy oil returning to the tank, Otis?

Pressure cannot be "improved".

When pressure is at its highest, oiling is at its worst.

You can only adjust the excess pressure dumped into the gearcase.

....Cotten

[otis71]

I’m using a Dixie sending unit as it’s all I can find find. Even with the light on there’s a reasonably steady flow of oil. It doesn’t appear frothy. It’s very worrisome to see the light on. Maybe I can put a gauge on it. What would be the minimum pressure when hot to safely run?

[T. Cotten]

A gauge just takes your eyes off the road, Otis!

It can peg when its cold, and drop to nothing when its hot.

A Pan doesn't care as long as there is flow, which is at its least when the pressure is highest.

And yeah, that's a DIXIE in my previous pic. Want to buy another?

....Cotten

[otis71]

I’m going to put the first pump back on with a thinner gasket and keep a watchful eye on it. A previous owner brazed the chain oiler up. Would that effect anything or possibly partially block a passage? I tried posting a picture but it’s not loading.

[T. Cotten]

... previous owner brazed the chain oiler up. Would that effect anything or possibly partially block a passage?...

Probably.

....Cotten

[otis71]

While preparing the first pump for reinstallation I notice a small crack where the cap threads in to close off the pressure relief valve. Brazed it up and used a thinner gasket, hopefully curing the problem.