Lower unit Problem

[sampark]

When I put my boat up for the winter I drained the lower unit and it was full of water again.This lower unit has been resealed four times in the last two years twice by me and twice by differnet omc mechanics.I have it setup in a black and decker workmate now i have pressure tested and vacum tested it .It holds pressure and vacum fine.The problem has to be when it is running.I just checked the prop shaft and i have .004 runout at the end of the shaft.Is this too much and will this cause it to leak? Thanks Sam

1993 johnson 200 vj200sletc


Modified by sampark at 8:36 AM 1/24/2010

[gearcaseman]

I don't think it would, .004 at the end of the shaft is hardly anything at the sealing surface. Are you giving the P&V test enough time to check for pressure changes? Also check the housing for cracks. It's best to submerge the case completely while under pressure to check for bubbles. The vacuum test will only check the outer propshaft seal and outer driveshaft seal, otherwise the pressure test will show any leaks from the entire case.

[sampark]

I have left the pressure on it for 24 hrs and it hasn't dropped.I will submerge it in water and see what happens. Thanks Sam

[gearcaseman]

That should be good enough right there, If it held pressure that long you're good. I would take a close look at the D.S. & P.S. outer seals very carefully. E.P.

[sampark]

If I move the drive shaft side to side it leaks at that seal but i assume that in operation the drive shaft is centered in the crank and would not allow this side to side movement. Thanks Sam

[gearcaseman]

Yes, that is correct. The shaft is a two piece, and that allows the movement when not bolted to the motor.