Pressure testing my drive

JASinIL2006

Vice Admiral
Joined
Feb 10, 2012
Messages
5,729
Since it's cold and snowy here in Illinois, I'm trying to do some boat maintenance to keep me busy. I pulled my Alpha One Gen II drive and have it tucked away in the basement. I thought I'd pressure test it when I was changing the drive lube, so I cobbled together this little device, based on others
I have read about here:
image.jpg

I drained the drive lube, which looked pretty good, with no signs of water or milkiness. (Last year I changed the lube and replaced the impeller with a pump rebuild kit. Everything went back together fine and the drive ran great last summer.)

When I attach the pressure tester to the drive via the vent hole and pump it up to 11 or 12 PSI, I lose about one PSI over a time span of about 24-36 hours. Am I correct in assuming that's not acceptable? I've read of people checking for leaks with a bubble solution, but I'm not entirely sure where to check. I imagine I'd want to check the union between the upper and the lower half, the drain hole and the venthole (where my gizmo is attached; I probably also should check to make sure my pressure tester itself isn't leaking).

Will the bubble test show a leak that slight? Any other locations I should be checking? Is this something I even need to worry about? The boat spends about 3 weeks straight in the water each summer; the rest of the time it's on the trailer or out for day trips (if that matters).

Thanks!

Jim
 

MarkSee

Lieutenant Junior Grade
Joined
Sep 10, 2010
Messages
1,172
Re: Pressure testing my drive

I think you have nothing to worry about as that just might be the smallest of leaks in one of the tester fittings as you think.
I thought I remember reading that one of our super-techs on the site mentioned about pressure testing for only a couple hours and if it held for that length of time, you were good to go.

When I pressure tested my Bravo 3 at the end of 2012, I found similar to the loss you have; maybe even a little more.
When I pulled the drive a couple weeks ago for the annual inspections, found no water in the gear oil when I drained it or gear oil in the bellows.

Mark
 

bspeth

Senior Chief Petty Officer
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Aug 30, 2013
Messages
758
Re: Pressure testing my drive

a drop in temp could change it that much,imo you are ok.
 

achris

More fish than mountain goat
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May 19, 2004
Messages
27,468
Re: Pressure testing my drive

If it holds 5 psi for 20 minutes, then 15psi for 30 minutes... Fill it with oil and enjoy the rest of winter.

As already mentioned, temperature change or a leaking tester fitting could easily account for your loss. Try plugging the tester and pressurizing it, see how it goes on its own.

Chris.......
 
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JASinIL2006

Vice Admiral
Joined
Feb 10, 2012
Messages
5,729
Re: Pressure testing my drive

Thanks, guys. I'll repressurize and try turning prop shaft, etc.

Fun times, I hadn't seen that page from Don before. Dang, that guy is still helping me out...

Thanks again!
 

JASinIL2006

Vice Admiral
Joined
Feb 10, 2012
Messages
5,729
Re: Pressure testing my drive

Pressure tested this afternoon per the instructions in the link from Fun Times. Everything looks great! The drive is now filled with lube and awaiting Spring. As am I...

Thanks again!

Jim
 
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