replacing seals on 90hp 18 year old merc ow difficult?

[wn6ngp]

I've got a 90hp 2 stroke s/n OT087666 Merc. Water is getting into the lower unit as evidenced by that milky look. I've ruled out the gaskets on the filler plugs so I'm afraid its seals inside. I've done all my own work on this motor myself but after reading the shop manual I'm intimidated. Looks like I'd need special gear pulling tools and there's warnings about don't lose 3 little balls and the cam follower etc. Is this something best left to someone that does it for a living as opposed to shade tree myself. I've replaced impellers etc but this seems quite a bit beyond that. Looks like the hold pressure test would be a good thing to do but again special tools required.

 

[flyingscott]

Yes

 

[The Force power]

Without the proper tools/knowledge & ambition, it may be better to get it done by someone that's familiar with this

 

[Chris1956]

A lot of time the leak is under the water pump base, in the driveshaft seal. I would recommend you get a new water pump base (with it's new driveshaft seal) and install with anew gasket and O ring. If she still leaks, you can revisit.

 

[Faztbullet]

Also make sure your use a marine gear lube as some of the automotive ones will aerate and turn a whiteish/yellow. Automotive lube are for vented transmissions. I had a customer bring me his unit severalas he stated it was leaking. After several days of vac and pressure tests found out he was using Autozone 80W90 GL oil. Filled with my Serria synthetic blend and ran several weeks inspecting and no water intrusion .

 

[The Force power]

If you decide to take on the challenge; get the tools needed follow instructions in the manual and you ask us for help.:lol:

 

[Chris1956]

One more thing. Occasionally the bushing/seal on the shift rod will leak. Those can be replaced. My V6 had a removeable bushing/seal, that screwed into the gearcase. A punch/hammer was used to unscrew it.

I made a spanner out of a black pipe connecter, using a grinder to make some "ears" to install the new bushing/seal.