odd gearcase issue with '65 40hp johnson

[dafox99]

Hey guys .. it's been years since I've been on the forum. I haven't had time to take the old gal out on the water.

So, I clearly have a lower unit leak. I have new plugs and washers. I pressure test the gear case at 5 psi .. and it holds all day. BUT, I fill the gearcase, take it out and run it. When I pull the plug, the lube is gray-ish and emulsified.

I don't know if I can even find a seal kit, but wondering what I'm sealing. Maybe the prop seal leaks when it's under power?

All thoughts welcome.

Thanks.

 

[tevans720]

Re: odd gearcase issue with '65 40hp johnson

If its holding good my only thought would be your fill plug seal. And I thought that you pressurize it to about 12 psi. Maybe it holds at 5 but not 12. not sure but give it a shot

 

[dafox99]

Re: odd gearcase issue with '65 40hp johnson

Ah ... could be. I was a boat mechanic from '75 - '82, but it's literally been 27 years since I really did this. Maybe the pressure test is higher. The seal is new, so I'm thinking it's not that. prop shaft doesn't appear to be bent, which would leak when it's turning. I'll see if I can confirm the pressure check. Thanks.

 

[F_R]

Re: odd gearcase issue with '65 40hp johnson

Actually, try it at lower pressure. High pressure "blows" the seals tighter shut. (Pushes the seal lip against the shaft). Pressure also pushes the propshaft outward while running it pushes it inward. There might be a groove worn in the shaft at the normal running position. Are you sure it is getting water in it and not foamed up with air? Using outboard gearcase oil?

 

[dafox99]

Re: odd gearcase issue with '65 40hp johnson

wow .. never thought of lower. Some many years ago, one of the guys on this forum said about 2 psi was all I needed. Hmmm .. well, I'm assuming it has water. I've never actually seen real water in it, but I pour that honey colored ouboard lower unit lube in (actually, especially for this electric gearcase .. the one with the two coils and chinese-handcuff springs that grab the shaft) and when I check it, it is sort of gray and foamy. Heck .. maybe it doesn't have a leak? it's always full.