Reply To: Freezing lower unit

[Don]

Hmmm, this is an interesting topic indeed.  The way I see it, those cracks didn’t create an air leak into the pump, because the outer diameter of the SS impeller housing is sealed from air/exhaust.  I’m guessing that the cracks caused the top of the casting to be uneven/not flat, which distorted the SS impeller plate, which may have created an air leak between the bottom side of the impeller plate and gear housing outer diameter mating surfaces.  I would definitely replace the SS impeller plate, it may have been distorted from the bad fit.

I’m not recommending this, just theorizing here.  What would be the harm in drilling relief holes through the bottom of those sealed cavities??  Again, those cavities are sealed from the water passages underneath the impeller plate, so their would be no air leak.  Any water inside those sealed cavities would drain out once the engine is out of the water….

Perhaps you new g/c housing might have these relief holes already…

What do you think Frank??