Hitchcocks Forum

I’m replacing the oil seals on the inner primary case. With regard to the larger crank seal and the crank seal washer (page 6 part 20 and 21)… I have the following question:

The inner primary seal prevents the primary oil from leaking out –
What prevents the engine oil from leaking through the bearing and leaking between the engine and the inner primary case?

There’s only a steel washer between the open bearing and the inner case.
Thanks - Jim

I don't know but it doesn't! Seriously, there is a very slight ingress on mine (I have a belt primary fitted so it is obvious) but only enough to pick up on a finger, easily wiped off with a bit of kitchen roll during routine maintenance. I suspect the real reason it doesn't is that the large engine breather on these models keeps the crankcase at a balanced pressure, at least most of the time. Earlier model Twins (Super Meteor and Connie) were much more prone to leaking at this joint.

REgards, Mark