What the–? What’s this tube you are drilling out? Are you saying the copper tube that runs up the side? That tube carries oil from the bottom to the top bearing. Not what you are looking for here. Stand by, I’ve torn down a junk powerhead to take some pictures to show where the oil suction line is. But of course, the camera battery is dead. Charging. Be back later.

I see there is still some confusion, so I pulled it down some more. fleetwin, pressurizing the crankcase probably would only lead to a false diagnosis because there is no vacuum to the intake manifold if it isn’t running. However, it may be useful to diagnose the carbon seal leaking. Yes, you can see the bleed hole by removing the carburetor. But you can’t see the one in the oil collection groove without splitting the case.

OK, again, this is a 1955, with lip seal in bearing, no carbon seal. But I am sure they are interchangeable.

Note the oil collection groove that grabs any oil that gets past the bearing shell. That grabbed oil passes through the little hole, back to the intake manifold. Note the vertical slot from the groove. That drains off any oil that gets above the bearing in spite of the return groove.

You can also plainly see the oil supply from the lower bearing.

(Nice clean motor, huh?)

upload image online

windows print screen

Just thinking, the carbon seal must remain in contact with the top of the bearing shell in order to maintain a constant seal as it runs. Is there an unusual amount of jumping up and down of the crankshaft as it runs? I know, hard to tell. But something to consider.