I have tried this.... it isn't too severe... as long as the drain port is wide open. Besides, there is a fair amount of air space above the oil level in the exhaust chamber.. so all that happens is the oil sprays out. As I recall, it works quite well to coax out the last dregs of sludge. The item in the pump that takes the greatest "stress" during this operation is the reed valve. But it usually has a restraining plate to prevent it from bending too much. I think the key point it to give the pump small doses of the oil.
Dave Cooper
Created on Sunday, May 06, 2001 1:28 AM EDT by David Cooper