gear lube loss

[jebby]

Hi guys, starting to clean up and get through my new to me boat to get it where it needs to be.

bellows, gimble bearing, u joints, lower throttle cable were all done a few weeks ago. Took it out once since then and everything was great. its been sitting in the drive for a week, noticed a small patch of gear oil. about 1 sq foot just a skim not a pool. cant see it dripping anywhere (not that it matters im sure it would run down the skeg and drip there) any advise on common culprits and where i should start?

 

[achris]

What ya working on?

 

[jebby]

oops, guess I should offer the information eh?
its a 4.3 alpha 1 gen 2 (1992)

 

[Bt Doctur]

drain screw washer propshaft seal shiftshaft seal lower driveshaft seal(s)

 

[jebby]

thanks for the starting places. I know its not the drain screw (was smart enough to go fresh washers and they are clean and dry under it) hoping its the propshaft seal so I don't have to pull too much apart. any tips for diagnosing?

 

[achris]

Pressure test.

 

[Rick Stephens]

Unfortunately no shortcuts. Pull the drive, drain the oil, pressurize and look for leak. Use soapy water spray to locate. Seals between upper and lower are harder to locate since you then have to split the cases and plug the passageway between them. That's the way it's done if you want it right.

 

[jebby]

thanks guys, forgive my ignorance as im all new to this. am I splitting the lower unit and pressure testing that or do I need to pull the whole drive?

 

[achris]

Pull the whole drive initially. Gen IIs upper can't be tested separately. And testing the lower separately involves somehow plugging the oil passage (between upper and lower)..

Chris...

 

[Rick Stephens]

You can drain and reuse the oil if it is fresh. I build a roll around stand for my drive, with slot cut in the top that the drive slides into with the cavitation plate resting on the top of the slot. Then I can pull the drain plug and the top plug and let it drain into a clean container. Walk away from it for a while - let it all come out. That way oil isn't sealing up seal when you pressure test.

Build a pressure tester of your own. I built mine out of a foot long hunk of 1 1/4 PVC, some PVC fittings, a $14 pressure gauge and a schrader valve to put air in the tester, and a short hose with a fitting off the end of a oil hand pump for filling the drive. I found one that was metal.. I hit it with the air hose to 10 lbs and spray the seals with soapy water. If I don't find anything, I spray it again while turning the shaft. Check shift shaft, output shaft behind the prop - have to remove the prop, and input shaft at the yoke. You can almost do the upper case output shaft through the exhaust hole.

Last one is under the water pump which requires splitting the cases and sticking a cork in the oil passageway and pressuring the lower by itself. If you are losing air and the prop shaft isn't leaking and the shift shaft isn't leaking, you know under the water pump is the problem,

 

[achris]

I also built a drive stand (in metric of course. ) Photo below...

Here's a link to a pressure test thread. Lots of different designs there...
https://forums.iboats.com/forum/eng...e-pressure-vacuum-check?p=2811656#post2811656

Chris..........

 

[jebby]

Thanks guys ill be picking at this over the next little while. to add to the saga, I opened the gear lube dip stick last night to see how much i lost and its not down any and the leak appears to have stopped. also got a slight hiss like the case was slightly pressureized. currently not leaking. will update as i go.