Bravo 3 passed pressure test but fails vaccum

[VernJ33]

Hi All, I have a bravo 3 that failed a pressure test and it was leaking from the inner prop shaft seal (the seal between the big and small shaft). A huge thanks to Alldodge for his write up especially the hose clamp trick it works perfectly. Boat is in salt water and it kicked my butt getting the bearing carrier off. I broke 4 1/2 inch breaker bars, after more heat and pb blaster i finally got it off. Got everything back together, pressure tested it to 10 pounds and it held it over night. Pulled vac to 5 pounds and it drops pretty quickly.
I know merc says you dont vac test the drives but i see that others do and they hold vac. So is there another hidden issue and is it just maybe one of the seals isnt holding vac but pressure and it doesn't matter.
Drive was disconnected for test. Thanks again.

 

[nnl1987]

Is your vaccum tester working? Just a thought (mine was broken/ not working properly till I borrowed one and discovered that was the problem)

 

[Scott06]

Is your vaccum tester working? Just a thought (mine was broken/ not working properly till I borrowed one and discovered that was the problem)

Good point minor leaks in tubing etc really affect the performance of vacuum systems like oil extractors

 

[VernJ33]

Yea it's working. So i pulled vacuum, and crimp the line right at the fitting. The gauge held pressure, I took of the crimp on the line and the gauge went to 0.

 

[alldodge]

B3 drives have seal issues due to the types of seals. Did you install the one piece double seal or 2 individual ones?

Squirt some oil on the seals and rotate a couple times to see if vac seals better.

 

[VernJ33]

I installed the one piece double seals. Drive was installed and boat back is in water. Had a good trail run with no issues. Thanks again to Alldodge for that write up.