Is an old drive worth the repairs

[SSTKO81]

1981 SeaSprite 140 with the original (I believe) pre-alpha still hanging on the transom. Pulled it yesterday to replace a damaged lower shift cable and the whole drive bellows was full of gear oil. My immediate assumption is that the upper driveshaft seal finally gave up. It looks like I can remove and get a replacement seal from the local napa without much issue, (Probably have to buy a spanner too) but it’s got me wondering if I replace this seal is it just gonna waterfall from there? I’ve already replaced the upper bearing on this drive about 8 years ago. I don’t like the idea of having to blow this whole thing apart and try to rebuild it anymore than I have too. I don’t know that I’ve got the skills or tools.... Thoughts? Input? -also, does anyone know how to find my gear ratio?

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[nola mike]

An input shaft seal isn't too tough. Yeah, might be worth doing the other 2 drive shaft seals whole you're in there. Parts are cheap, no special skills needed. The actual internals seem pretty robust if maintained, and are more working/catastrophic failure than slow wear. Unless you buy brand new you're in the same position you're in now. My advice is to buy a cheap Craigslist spare in the off-season. As for gear ratio, you should have a 1.98. to tell, you can pop the top cover off and count the gear teeth. Or turn the prop and count to the number of times the input shaft spins per prop revolution.

 

[SSTKO81]

Thanks Mike, I really don’t wanna spend another summer on the trailer making repairs so I’ll probably give the seal a whirl and keep my fingers crossed. I can find used drives on eBay or marketplace all day for $200 so that’s a short term option if it comes down to it. If I had the money I’d buy an SE outdrive/gible/transome and not worry with it for the next 20 years, but I don’t have $3000 just sitting around.

 

[achris]

Looked at the photos. That's an MC1 drive. Merc never made a drive called 'pre-Alpha'... (Actually 17 drives were before the Alpha One, so technically they would all be 'pre-Alpha').. :noidea:

The ratio is likely to be 1.98:1 if it's behind a 120 or 140 engine.

As already mentioned, once you have the drive gear and bearing pack out, the other seals in the top box are easy to get at.
You may find the front seal has grooved the yoke. 3 options. 1 - new yoke, 2 - Speedi-sleeve the existing yoke, 3 - set the new seal 1mm deeper into the carrier (the seal then rides on an unused section of the yoke, effectively a 'new' surface). I've used option 3 many times, and it works a treat.

Chris.....

 

[SSTKO81]

Thank You mike and chris for your input! I was able to get everything taken apart, sourced a seal from Napa, cleaned everything up and got it back together. I’m pressure testing it over night and if that goes well I’ll have the new shift cable in tomorrow morning and be ready for the weekend!

 

[achris]

Pressure test only needs to run for 15 minutes. Leaving overnight may lead to a false 'fail' indication. Leave it 15 minutes, if no leak, you're golden.

Chris........

 

[SSTKO81]

Pressure test only needs to run for 15 minutes. Leaving overnight may lead to a false 'fail' indication. Leave it 15 minutes, if no leak, you're golden.

Chris........

well I guess I erred on the side of caution it held all
night long . So back on it goes.