B40 oil pump removal

[dougc]

I'm not convinced my oil pump is working properly, although delivering a small amount of oil to the upper cylinder it's only returning a dribble to the tank return. I have read in the manual that the pump can be unbolted and withdrawn through the sump aperture. Having removed the sump plate and filter I'm struggling to see how there could be enough clearance to get the pump out, so I will not be unscrewing anything until I've had further advice from experienced BSA owners. (It's a 1960-61 trials engine with distributor points.)
Thanks

[DAVE BRADY]

good morning,

If the oil level in the tank is staying pretty much the same then you are not getting an accumulation of oil in the sump then the pump must be returning it.  The oil feed to the rockers is only a small amount anyway and the dribble returning to the tank could indicate that the pump is getting the the oil back efficiently.
When you removed the sump plate was there a lot of oil in there?

Dave.

[spaceman]

I'm pretty sure the oil pump fitted to the earlier B40's could be withdrawn through the sump hole. However, especially if this was a competition model, it may have a higher performance and larger pump fitted which may be too big to be withdrawn in the same way. It sounds as though this may be the case here.

In terms of the problem, the oil return into the oil tank should be via a healthy flow when you first start the engine. However, once the oil that has drained into the sump has been returned, the flow into the oil tank will take the form of slower spurts of oil. If the lubrication system wasn't working correctly, you would find oil accumulating in the sump after you've run the engine for, say, 10 minutes.

[dougc]

Thanks, I will put the sump and filter back in place and run it again perhaps for a little longer, taking note of the oil level in the tank before I beegin.