Type IV oil pump pin movement, Variation on 10 pumps Options

[bdstone914]

Notice the wide range of the depth above or below the pump surface.

I know @jakeraby pointed this out long ago but is there an easy fix or just use new pumps?
These are cores that are getting reworked.

[GregAmy]

"Outward" meaning "in" toward the engine? Doesn't seem like it can walk "out" toward the cover, it'll just stop there.

So where's the failure in this design? Inconsistent shaft length? It seems that if there's risk for the shaft to walk toward the cam, then that should have been a blind hole that the shaft sits in (with a hole for draining, if needed.

Pinning the shaft to the housing and letting the gear spin on it seems the "easy" button (it really isn't that difficult a machining operation).

[Superhawk996]

So where's the failure in this design? Inconsistent shaft length? It seems that if there's risk for the shaft to walk toward the cam, then that should have been a blind hole that the shaft sits in (with a hole for draining, if

Failure mode is overheating the engine opens the bore between the steel stationary shaft and the aluminum oil pump housing loosening the “grip” of the press fit. Oil pressure can then get behind the stationary shaft and the housing and “push” the shaft toward the cam gear hydraulically.

Agree completely that a blind hole would have prevented all of this. Blind hole cost more to machine and tolerances on shaft length would have to be tightly controlled. I suspect that is why VW did what they did.