Bravo 1 preassure/vacuum test question
 

Finally got the drive together. Pressure test @ 15# 3 hrs no loss.
Question is do I also need to Vacuum test? I have the tool but don't know if necessary/applicable with Bravo.
I plan on leaving the pressure tool on until tomorrow then Vacuum if required. Thank you

Merc does not list nor recommends a vac test for alpha nor Bravo. They also changed the pressure testing procedures as well. It was never for 3 hours to begin with as that is way to long. The new procedurs can be found in the newer bravo service manuals.

Also when pressure testing your gauge needs to be accurate and it is wise to rotate the prop / propshaft by hand in fwd and rev as fast as you can to see any psi drops. Then it is wise to rotate the input driveshaft (u-joint assembly) by hand to watch for if psi drops.

Pressure testing is a good test and recommended the correct way but is not 100 % full proof that your drive will not leak gear oil.

Also too much pressure and or too long can hurt a internal seal or distort it.

BUP, Thank you. tested at 15# for several hrs, no drop at all, rotated prop and input shaft several times during test. Good to know about no vacuum I could not find any specs anywhere on this with Bravo. Gauges are professional quality borrowed from a friend. Ready to grease up and install.

Your welcome and possible one day soon I might need to call you about some CA info.

Have always done it as BUP quoted above. 15psi for 15min. Have found a leak in the past while rotating the propshaft. Good info there.

I had a suspected prop seal leaking before, but would't leak with 15 psi, even rotating shaft. Spraying windex on looking for bubbles. Took pressure down to 5 psi, and sure enough it would leak. I think the higher pressure was forcing the worn seal shut or something.

Just an experience I had. Replaced prop seals and was good.