Lower unit pressure test

[IS-217]

Hi all.
2008 starcraft I/O 4.3L merc.
I am wondering if I can do a pressure test on my lower unit while its mounted on the boat. I redid some seals and a new impeller this spring because there was a little bit of water in the gear oil. After reinstalling it on the boat a friend asked if i did a pressure test but i did not. Now that its on the boat i dont want to risk ruining the gasket. So my question is can i do a pressure test while on the boat. I haven’t filled up the gear oil yet. My inboard does have an oil reservoir and ive read if so i cant do the test on the boat. Im curious if this is true or not. And if true why can’t i do the test? Isnt the oil line sealed at the reservoir?

 

[Scott06]

Hi all.
2008 starcraft I/O 4.3L merc.
I am wondering if I can do a pressure test on my lower unit while its mounted on the boat. I redid some seals and a new impeller this spring because there was a little bit of water in the gear oil. After reinstalling it on the boat a friend asked if i did a pressure test but i did not. Now that its on the boat i dont want to risk ruining the gasket. So my question is can i do a pressure test while on the boat. I haven’t filled up the gear oil yet. My inboard does have an oil reservoir and ive read if so i cant do the test on the boat. Im curious if this is true or not. And if true why can’t i do the test? Isnt the oil line sealed at the reservoir?

you might be able to by clamping off the line tot he reservoir.

The gasket for the outdrive is like $10-15... pretty cheap to know it holds pressure. if you hadn't done the shift shaft seal I would look closely at that. I got a fishing line in prop seal of my 2004 vintage gen 2. So I re-sealed it given the age. The only seals that were close to being gone were the shift shaft seal.

 

[IS-217]

Thanks for the advise. I will try to test as you said.