circa 1976 Mercury 9.8 gearbox siezed

[capezig]

So...this outboard was on a sailboat donated to a non-profit I work with. About 1976 Mercury 9.8 with the brown trim decals on the cowling. After dropping the lower unit off, the engine rolls over smoothly on the pull cord, no problem there yet. But, the lower unit is seized up tight. The shifter rod will not rotate and the propeller shaft will not rotate, except clicking nicely the wrong way. I opened the drain plug and vent and blew air through...nothing came out but little dry corrosion bits, not a good sign. I have finally gotten it so that some Marvel will find its way from the vent to the drain, and will fill up through the vent with the drain plug in. Of course no matter how long I let the Marvel soak in there, nothing that should moves, yet. I have started to break the prop free to go in that way to remove the corrosion if possible, but it is slow going

Anybody have some words of wisdom for trying to tear down this lower unit to get it moving again....and no, replacement is not an option...and junking is not really an option either if there is a chance of breaking this loose.

 

[Chinewalker]

If it's seized, it'll need all new bearings through the gear case. Freeing it up as is and trying to use it is a recipe for failure. Remove the rear spanner nut, pull the rear carrier out (with the propshaft and reverse gear), remove the water pump, remove the bolt from the bottom of the driveshaft, and pull the driveshaft out. A bench vice, rubber mallet, and gentle heat from a propane torch should facilitate disassembly. A service manual would be HIGHLY recommended.

It's possible, when you get it apart, that the gears might be shot, too. Won't know until you get in there.

 

[60sboater]

Sounds like the l/u oil may never have been replaced and those screws were in since the factory. Let us know how it goes with your repair efforts.