50 hp 1987 Mercury outboard driveshaft seals - Part 1

[tumbleweed32]

Removed lower unit from 1987 50 hp Mercury outboard for servicing. Re-installation should have been straightforward, but for reasons I could not figure out, the lower unit, though aligned properly, would not go in the last1/2 inch or so. Tried turning the flywheel to align the splines but still no go. After having tried to install it and taking it out (about a dozen times) to try to figure out what could be preventing it from seating correctly the second last removal resulted in dislodging a rubber piece later identified as the top seal of the drive shaft.It was placed back onto the drive shaft and another attempt was made to install the LU. Still no luck, but this time another piece came out, later identified as the bottom seal of the drive shaft.

 

[GA_Boater]

When the LU goes back on except for the last half itch, it's usually the shift shaft or the water tube. The stuff about upper and lower drive shaft seals makes no sense. Drive shaft seals are under the water pump, so it must have fallen out too.

 

[schematic]

ditto on Ga, but I have had the crank shaft seal come off and prevent leg installation. After several attempts, I looked up the center housing and seen the loose seal

 

[tumbleweed32]

My apologies to all. I'm new at this and was not able to post Part 2 right away last night. The following text is a continuation of Part 1 above: The explanation and diagram in the manual (page 5B-22 - lower unit) were short on detail as to the correct way to re-install the seals so I took the motor off the boat and brought it into the shop. The techs were not familiar with these seals. When they tried to install the LU to the motor, they ran into the same problem I had. They looked up some information on line and contacted other techs, but no one had heard of these seals. They concluded that that the bottom seal was unnecessary. They re-installed the LU with the top seal in place but left off the bottom seal.

Somehow I think that was not the right solution, but I am not a tech. Will running the motor like this be OK, or will it cause some damage?

Any help or advice greatly appreciated.

 

[tumbleweed32]

My apologies to all. I'm new at this and was not able to post Part 2 right away last night. The following text is a continuation of Part 1 above: The explanation and diagram in the manual (page 5B-22 - lower unit) were short on detail as to the correct way to re-install the seals so I took the motor off the boat and brought it into the shop. The techs were not familiar with these seals. When they tried to install the LU to the motor, they ran into the same problem I had. They looked up some information on line and contacted other techs, but no one had heard of these seals. They concluded that that the bottom seal was unnecessary. They re-installed the LU with the top seal in place but left off the bottom seal.

Somehow I think that was not the right solution, but I am not a tech. Will running the motor like this be OK, or will it cause some damage?

Any help or advice greatly appreciated.