Oil pump gear clearances

[Rudgeman]

Can anyone tell me what the maximum axial clearance for the oil pump pinions are please ?

Many thanks,
                         R

[RichardL]

Rudgeman,

I don't think that would be a published specification, so what you'll get is opinion, some more worthy than others. I am guessing about 0.004" so that I can be corrected by someone who has played with this far more than I. How much clearance have you?

On the other hand, Julian may jump in here with the most obscure BSA service bulletin imaginable describing the clearance and the rate of spiraling of the gears, etc. :)

Richard L.

[Swarfcut]

The oil pumps that I see mostly have neither radial or axial clearance on the gears.  It is rare to get a pump that turns freely. Generally the Mazak Body seems to shrink over time, so if there is any axial clearance left you are lucky. In most cases the pump binds up as the bolts are tightened, and circular witness marks are produced on the end plate. Making a good pump is either a case of mix'n match of random parts or careful relief of oversize components.

 Swarfy.

[Racker]

As I am renovating my A10 oil pump I came across this old post on the problem of sticky pumps. Indeed it is causes by deterioration of the pump body. It is however not so much a shrinking of the material but local expansion or swelling of the Mazac. This can be removed by careful lapping with a paste and or abrasion with very fine emery paper. It is time consuming but proven effective.