56 johnson FD-10 Driveshaft seal question

[TLanglitz]

I noticed lube seepage on my 15 horse lower unit, so I decided to have a look inside and do a reseal. The good news is it didn't seem to have water inside and the gears, cluch dog, shift fork are all in excellent condition. The drive shaft is a bit worn at the lower unit seal, but it doesn't seem bad enough to worry about yet.

My dilemma is this... The seal kit came with a drive shaft seal that is the correct diameter, but about half as thick as the existing one in the lower unit. The original, which I haven't removed yet, is about a half inch thick. The new one is about a quarter. If they were available individually, I'd be tempted to buy another narrow one and install it on top of the other new seal. I think it would fit. It is the correct seal kit... bought it from Vintage Outboards online. Only that seal is different. The old seal doesn't look too bad, but I'm sure the rubber is somewhat worn. Have any of you run into this? Did the smaller seal hold up? Would I be crazy to just leave the orgininal one in?

By the way .. the seepage was coming from a small crack in the lower unit cap/skeg. I have a mig welder with an aluminum spool, and have welded aluminum before, but I'm a little worried about trying this one because there is no sure way to clean the lube out from the inside of that crack. I'm leaning toward JB weld for aluminum on the outside of the cap only, and looking for a replacement cap for later. If the JB weld falls off, I would see that easily before any damage is done. I don't think the crack is in a place that will let it grow ... but the more I think about that, the more I lean back toward welding it.

I'd appreciate any advice
Tom

 

[samo_ott]

Re: 56 johnson FD-10 Driveshaft seal question

I brazed my skeg once on a 5.5. I took if off to do it. It lasted for years until I just sold the engine this year. I learnt the hard way to change the LU oil at the end of the season before the water in it freezes up! I used an aluminum rod and a propane torch. Was quite easy actually. A MiG with an aluminum spool should do the same. I just bought that same setup but have not tried it yet.

 

[TLanglitz]

Re: 56 johnson FD-10 Driveshaft seal question

Welding aluminum with a mig isn't all that difficult. Its just a pain switching the tank to pure argon instead of the mix, and then changing the cables over to the spool gun.... all for a one inch crack. The trick is to get the aluminum clean to start with, which I don't think I can do well enough with this crack.

 

[F_R]

Re: 56 johnson FD-10 Driveshaft seal question

Yeah, you fortunate guys with the welders. Us mortals use JB Weld. It works great. If you can put it on the inside, it might look better.

The new seals are thinner. Tho old original CR brass ones are no longer made. Sometimes they do use two, one down and one up. But one will seal as good as the original.

 

[TLanglitz]

Re: 56 johnson FD-10 Driveshaft seal question

Thanks F R

I ended up welding the cap and used the new seal. The lower unit is back together and waiting for me to pick up some lube to fill it with. I'm still amazed at how good everything looked inside. That motor is one year older than I am, but in a whole lot better shape. <lol>

 

[F_R]

Re: 56 johnson FD-10 Driveshaft seal question

Thanks F R

I ended up welding the cap and used the new seal. The lower unit is back together and waiting for me to pick up some lube to fill it with. I'm still amazed at how good everything looked inside. That motor is one year older than I am, but in a whole lot better shape. <lol>

Yer just a kid. I graduated high school before that motor was made.