- Tue Jul 15, 2014 8:05 am
#37424
@Norm: well, of course, it's up to you whether you reply. I think I do know what wet-sumping is, although I'm always happy to be corrected (as I showed earlier in the thread about the catch can). My understanding of wet-sumping is that sometimes, particularly when the engine is stopped at BDC, oil from the tank slowly flows "backwards" from the tank into the sump area beneath the crankshaft. My understanding is that this must necessarily happen very slowly, as the only path into the crankcase is seepage from the big end bearing, and seepage through the right hand main bearing seal. The Electra scavenge pump has roughly twice the capacity of that in the original engine, but still pretty small compared with modern day engines. When the engine starts, the oil in the crankcase is forced into a dense and powerful spray which fills the entire crankcase, such that large volumes of the oil are pumped into the breather pipe as the piston descends. Even if, as you say, it takes only a minute to fully scavenge the crankcase, that is still a long time to be pumping the dense oil/air mix into the breather. That is my understanding of wet-sumping, and I would entirely agree with you that it isn't going to happen while the engine is running because the scavenge pump has more than enough capacity to prevent it. If any of the above is wrong I'd be very happy to be corrected - I aim to learn something new every day.