Oil pump gears replacemnts?

Hi guys,

I just picked up an oil pump from Ebay. On the whole it's in pretty good shape, though on one of the output gears ( the one with the keys), has tried to eat something in its past and so a couple of the teeth have been damaged, tho not broken.

The result is that when turning the pump by hand the pump feels sticky/notchy, on occasionally jams solid. I've since taken a needle file to the protrusions on the tooth faces, which has greatly improved the action, though it's still not as it should be.

I was just wondering if you can still get internals for the pump? I had a look on Andover, but couldn't find anything. If you can still get the gears....Would they need lapping in?

ATB

S

The parts fiches do not show the gears being available separately, so unless you find someone with a pump that has damage some where else, you have a paperweight. I believe that it is false economy to install a used pump, too much depends on it. A used pump, in good condition, can be enhanced by stoning down the clearance between the gears and the pump body.

New pumps are crazy expensive, but so worth the piece of mind when you have (may have) spent $3K to $5K+ on the engine.

RS

If Norton followed BSA practice then the pump was assembled using selected gears from a bin, the operator fitted the gear and then tested before accepting it or trying another for a better fit, hence why making up one pump from parts of two pumps is fraught. So the gears where not available separate for that reason, you could never be sure they would fit.

My Combat pump processed a couple of the cam thrust washer tabs but I was able to clean up the nick in valleys, leaving some nicks in teeth end edges, till turned freely and and Peel on it just fine. Might want to call a major vender like Baxter's and get a good used one to go through mix matching til joy. I've priced new ones from $80 to $140.

Thanks for the replies guys,

I might bring the pump into work tomorrow and have a look at the teeth under the microscope, see if I can get the nicks out of them.

I didn't pay much for the pump, just seems a waste to discard it.

Just out of ignorance...Are they cast, or machined, or both? If I had to choose I'd say machined.

Dunno...

S

The first pumps were a zinc casting with narrow gears. Then they were cast iron bodies. and got wider gears. The gears have alway been machined steel.

Andover norton dealers are now quoting $480 for a new pump. I bought a new AN one for Rod R. maybe a little over 3 years ago and it was $325.
After market parts were at one time available, but I hardness checked them and were soft as butter. seemed hardly worth using.

For a little over 3 years I have been intermittently working on, and refining my oil pump test rig (3 AND 6 start) and testing procedures. I have demonstrated it at the last two east coast INOA rallies. Actually I have devised 2 machines. One is a dynamic rig and simulates an engine. For a bonus I can test the OPRV. The second rig is a static blow through system for testing the feed and scavenge. This is especially good for getting an idea how bad it may wet sump...

During this process I have learned quite a bit about them and their wear and failure mode. I've tested well over 2 dozen... 1 brand new AN , some very good ones, failing and totally shot. With out knowing what to look for it is hard to visually detect a bad one.

There are 4 leakage modes and only the common end lapping seems to be the one folks focus on. In the last week alone, I tested 2 pumps that were total garbage. The owners were very happy to find out before finishing the rebuild. A couple years back a NENO guy spent 3K on a "professional" norton twin rebuild and it was reduced to rubbish in under 400 miles...you guessed it. They used the old untested pump...that looked good...

Yes it is very nice to know how good or bad rather than a wild ass guess.
"Do you feel lucky punk, well do ya?"
I'll add a few pix when I get some spare time.
and NO I'm not taking in pump tests... yet.