Proper air pressure test

[zul]

I do most of my own repairs but when it comes to outdrive seals, I have a pretty good mechanic and I have him take care of that. He's doing my upper seals right now.

I have built up an air pressure tester where I use a bike pump to do the air pressure test. I found the idea right here on iboats! So, the tool and procedure from iboats is what I use ... drain the lube, remove the drive (it's an alpha 1 gen 2), air it up with the bike pump to 10 lbs and make sure it holds the air.

So -- my mechanic (who I believe is a pretty damn good greasy wrench mechanic) has a different way of doing it. He says to load lube into the outdrive and then air pressure test it. Seems to me, if we find a leak at that point, you have to drain the lube and you've got a big mess to deal with before you can get back into the drive.

Now, there is no way to convince this guy to do it 'the iboats way' instead of the way he has been doing it for decades. And most importantly, I don't want to insult him or **** him off. A good mechanic is hard to find in the desert of Arizona!

Is there any simple explanation or reasoning that might help me out here?

 

[Scott06]

Not likely folks are stuck in their ways. It would be more likely to leak a gas like compressed air than gear oil. Seems that would be obvious. I guess he’s not testing under vacuum as well?

hate to say it but he might not be that good of a mechanic. Maybe show him how it says to do it in the Merc service manual for the drive which I think is #14

 

[racerone]

Been using the EMPTY of oil method for over 40 years.

 

[Scott Danforth]

So -- my mechanic (who I believe is a pretty damn good greasy wrench mechanic) has a different way of doing it. He says to load lube into the outdrive and then air pressure test it.

find a new mechanic

 

[Rick Stephens]

So how would you know about a leak on the seals that are inside the two halves? - the output of the upper and the input of the lower are not visible. You could have a small oil leak there and not see it till a couple days later when it drips all over the floor.

Your mechanic will only find a leak when the customer brings the leg back.

 

[kenny nunez]

I always tested the 2 housings separately first with a combination of rubber gasket material, a piece of 1/4” steel and vise grips. Then again on the assembled empty halves.

 

[achris]

I always tested the 2 housings separately first with a combination of rubber gasket material, a piece of 1/4” steel and vise grips. Then again on the assembled empty halves.

Can't do that with Gen II. The drive shaft housing is sealed by the lower drive shaft, so the lower housing must be in place....

Chris.........