I know porous casting transfer is possible, and I believe HD had that problem on some shovelheads...

But porous casting transfer from trans to primary...???

Don't see how that's possible?

 

Leave whittlebeast out of this.

Same way gas migrates from the gas tank into the rear tire.

 

They guy said they replaced the motor so the motor was casing the vacuum in the primary just like a bad crank seal.. That caused the primary to suck on the clutch push rod hole.. Makes sense to me..

Add:
Technically it wasn't pulling directly though the motor-case.. Parts guys and salesmen don't have to be technical. I'm inclined to believe it was a misinterpretation of the facts somewhere..

 

A possible vacuum is one of the plausible reasons, but that doesn't include a porous case.

 

Why not?

 

While oil seepage through a porous spot is certainly not unknown, I would be surprised if the porosity were enough to allow enough air to move through the porous area to cause a change in pressure or vacuum.

 

Well air is thinner than oil so it should make it's way through easier.. The crankcase runs at a slightly lower average pressure than ambient.

 

I understand what you're saying, but "seepage" happens a lot slower than "flow". I find it hard to grasp how air could work its way through a porous spot in an aluminum casing fast enough, and at enough pressure, to force oil to go where it's not supposed to go.

If that were happening, I'd expect that everyone who's experiencing oil migration from the transmission to the primary would have been talking about the loud farting noises when they opened the transmission to check the oil level.

If you know what I mean.

Now, pulling oil past an improperly sealing clutch pushrod, that's more plausible.

 

Harley will have a transmission oil migration sensor on the 19's

 

Yeah, we laugh. Just wait.