1992 Mercury Force 40 hp gearcase vacuum test

[joshm]

My force shop manual only lists a pressure test of 10psi for 5 minutes. I was always taught to pressure and vacuum test, usually the psi and Hg" were the same values. Is there a value for inches of vacuum? Or is the vacuum test no longer necessary on somewhat newer outboards? Any help will be greatly appreciated.

 

[Frank Acampora]

Re: 1992 Mercury Force 40 hp gearcase vacuum test

With the type of seals these lower units have, they will either leak or they will not. Pressure or vacuum, it does not matter.

HOWEVER: If I were testing and my lower unit leaked, I would not want vacuum to pull in water. That would require me to open the gearcase to dry the water before replacing bad seals. Thus: I would not use vacuum to test a lower unit.