90hp lower unit pressure testing and vacuum test

[200090tlry]

Ok I fashioned up vac and pressure tester FYI Harbor Freight has $8 siphon red with handle for air,$15 fuel pump and vacuum gauge tester wham you have your test $23 bills. Confirmed it does both vac and pressure sweet! Should I do this test over night? My pressure at 10psi seems to hold strong,however vac test is leaking down very slowly. 5 minutes enough to confirm it's good to go?

[Sparkieboat]

nice tool invent..i will go out and make me one too..lol I am not sure how long you need to hold the pressure..
i would think if it has not moved in a hour that should be good.

[200090tlry]

Just read the manual

States apply pressure to fill hole, 14.2psi if it holds for 10 seconds your good. It also say's to put lower unit in water while doing the test but it's like 6 degrees outside and going to pass on this. So in all intensive purposes my lower unit is sealing as per manual. Over night I left it at 9 psi gauge didnt move at all. When I did vac test it did leak down but no mention in manual of doing this test at all.

[Sparkieboat]

*** only ten secs...then you should be fine. I would not worry about the vacuum test if it is not mentioned.

[99yam40]

If it is getting water in it then you have to find the place it is getting in at.

There is normally water pressure on the outside of the case when under water and from the water pump maybe. So I would think the vacuum test would be a better test for water flowing in that direction.
there is not normally pressure on the inside of the case, unless a little from heating up the oil and gears in a sealed containment. That pressure test would be for making sure the oil does not leak out. I forget from your other posts did both seals go in in the same direction?
Didn't you say the housing had a bunch of gouged areas where oring was sealing?

[200090tlry]

Well I think that vac test leak could be new siphon

Maybe a pressure test when cold is to tough im not sure. Im running it just way it is, enough of this lower unit crap lol. I put Mercury high performance lube in there. The cabelas seemed really thined out almost like engine oil maybe some general purpose lithium grease on driveshaft mixed in and is looking like water intrusion. Green lube is tacky, thicker 90weight and from what ive read best oil for outboards. Maybe it would be easy to spot water when i check again.