Gearcase troubles

[CBYS]

I just picked up a '77 40 plus that was supposedly running about three years ago. Everything appeared to be locked up hard but the price was right so I got it and began tearing it down to determine the problem. The motor itself appears fantastic. It's old and beat up but with a carb clean I think it would fire right up. However, the lower unit is completely locked up. Here's where my lack of knowledge of the proper names of things is really going to show so please bear with me. The two screws holding the cap on the gearcase (the part with the filler plug opposite the prop) came out easily enough so I was able to get that off. The whole thing is packed with nasty grease. One of the two screws above the water pump came out but the other is being difficult. I'm a sailboat rigger by trade though so getting old screws out of aluminum is no big deal. That's as far as I am getting. Is there anything I should know before proceeding? Any advise is really appreciated.

[Oyster 49]

Welcome to forum! Sounds like you are doing the right things. The gearbox should have heavy 140 grade oil or similar, never put grease in there as it will not mix with the water that gets into the box. The ideal contents of the box will be a creamy mix of oil and water. Change it often and if leaving the engine for a long time replace the oil.

If you remove most of the grease, and then soak in kerosine you should be able to assess the gears.

[CBYS]

I scooped out most of the grease that I can see but I'm looking at a disc with four holes in it covering the gears themselves. I can't figure out how that comes out.

Edit: Scratch all of the above. There was a roll pin on the prop shaft I wasn't seeing. The "disc with four holes" was the backside of the bevel gear. That's all out and the shaft is still frozen in place. The next step is to try to get at the water pump.

[1650bullet]

It sounds to me that the motor has been left on the back of the boat and never tilted out of the water when not in use. Thats why the shaft is hard to remove. Its badly rusted onto the gearcase pinion shaft. If you can remove the 2 screws that hold the gearcase onto the water pump housing, you can get an oxy torch to heat up the shaft thats rusted on and remove it.

[CBYS]

Thank you so much. That cutaway is a great help.

[CBYS]

Success on a couple of fronts. The power head is off the lower unit and runs. The fuel cock is leaking like crazy (that was expected) and the bowl of the carb is leaking as well (that was unexpected and I'm not sure of the fix). The throttle cable is seized and I'm not sure how it's in there or how to replace it. It's a bing carb. The lower unit is FINALLY apart and cleaned up. The shaft will now move fairly easily by hand so I think once that's back together I'll have a working motor. The next hurdle will be that throttle cable and leaking carb bowl. The fuel cock shouldn't be a problem at all.

[phil]

Boiling the pull out part of the fuel tap for a couple of minutes, should cure the leak, at least temporarily. Don't loose the tiny screw that holds it in place.

[1650bullet]

Watch this for a quick and easy leak free fuel tap.

http://www.youtube.com/watch?v=GGUDe89CIIM

One more thing. Because the gearbox has been a bit siezed up, You should fill it up until it overflows out the filler plug. The reason why i would recomend this method is because when its that full, the excessive amount of oil will pressurise out threw the pinion and prop shaft bushes and push out any dirt and grit, It will also thoroughly lubricate evrything as well. I know it sounds crued, But its a seagull remember. Normal way to fill the gearcase is to lay the motor spark plug facing the ground--Remove filler plug--Fill with oil till it overflows--screw plug back in--And put it in a test tank and give it a run. I normaly run a litre of pre-mix threw it till it runs out (about 25-30 mins)