Two upper seals

[dissturbbed]

Is it possible to replace both the two seals i have circled in yellow from the bottom instead of pulling out the yoke? The manual states to replace them from the top, kinda afraid to do that since a lot of people have broken the top plate bolts rendering the gear housing useless.

 

[achris]

Your picture is not showing up. Try posting it to a image hosting site and linking it here. If the seals are the 2 in the bottom of the drive shaft housing, then you absolutely must remove the top cover and yoke to replace the upper one...

Chris.....

 

[ktbarrentine]

Not seeing the picture...... and you don't tell us what vintage drive you have. So I will assume Alpha-1 gen II. Sorry, have to fully disassemble the upper gearing to replace either or both of those seals. If you are pre-gen II, then you could replace the bottom of the two seals from the water side, but the upper seal still requires upper disassembly. Yes, the upper cover bolts can break, but that is the exception, rather than the norm, and they can be drilled out/removed if that happens relatively easily

 

[Bt Doctur]

Alpha1, MC-1 one seal from the bottom one seal from the top
Alpha GEN II both from the top

 

[dissturbbed]

Your picture is not showing up. Try posting it to a image hosting site and linking it here. If the seals are the 2 in the bottom of the drive shaft housing, then you absolutely must remove the top cover and yoke to replace the upper one...

Chris.....

I hope the pic showed up, The bottom seal looks torn up but i cant see the one behind it, it all started when i replaced the water pump like most people when i installed the drive shaft it tore up the bottom seal but not sure if it messed up the upper seal as well. Should i go ahead and replace the upper seal as well? Does it usually mess up the upper one when you install the shaft? btw..it is a 1978 pre-alpha mercruiser 120 hp.

 

[ktbarrentine]

The upper seal should be ok... It rides on the upper shaft in the upper assembly. The one you tore up rides on the vertical shaft of the lower assembly. It is easily replaced without having to take apart the upper drive. Invert the upper assembly on a work bench and it makes it much easier. How does the shaft look where the seal rides? If it is grooved (like, you can catch a fingernail in it), you can position the replacement seal a few thou from the original original position and the seal will ride on fresh shaft metal. If you have the O-ring groove on your vertical shaft, recommended NOT putting the O-ring back on....This may have been what tore up your seal in the first place. The later versions of Alpha-1 pre gen II even did away with that groove for a couple reasons, that being one of them.

If you are still not sure about that upper seal, you can plug the oil gallery port (where the upper and lower join halves) and pressure test the upper by itself to see if the seal is holding (as well as the yoke seal, too.)... Then pressure test the entire drive after reassembly to check everything.

Hope you are using OEM manual #4....

http://boatinfo.no/lib/mercruiser/manuals/mercruiser4.html#/50