Is Mercruiser Alpha One Gen I lower rebuild a DIY job?

[spoolin01]

Back again for more advice. Bought a used Alpha One Gen I upper/lower in hopes of getting back on the water quickly, It had oil in it so all I did was an external inspection - shafts turned easily, quietly, and smoothly, and it appeared to have been a fresh water unit - a vacuum test, and a quick look at the lower drain plug and oil.

When I opened it up to check the water pump I noticed some issues. The "water" seal in the bottom end of the upper had disintegrated, and the seal groove in the shaft looks bad to me. It's V-shaped and measures at least .007 less than the shaft. It's so polished and perfect, could that V have been done deliberately to clean up the wear? Anyway, maybe worse is that once I popped the water pump base out, the shaft wobbles around and you can watch the bearing below the retainer move back and forth. There's some seal wear there as well, but not nearly as bad as up top.

I'm taking it to the shop today for some advice.

My question is, if I need to replace the drive shaft and don't want to pay the shop price for a new one, is this something I can do myself? I've got the bearing retainer and pinion nut tools on order (I've got a couple of other lowers I want to try to get running again), but wanted to ask if rebuilding the lower - to whatever extent is needed - is practically speaking a DIY job?

I don't know what all that loose bearing might mean, but if the shop says this one may still be serviceable, perhaps with some adaptations to deal with the upper wear spot, I'll have them do the re-assembly. If they say I need a $300 drive shaft, I may try to find a shaft myself and do the job.

 

[Bt Doctur]

Anyway, maybe worse is that once I popped the water pump base out, the shaft wobbles around and you can watch the bearing below the retainer move back and forth. There's some seal wear there as well, but not nearly as bad as up top.

Nope perfectly normal wobble. .If you have a pre-load pin on the driveshaft ,it pushes downward to set the preload. if you have a retainer nut for the newer drive ,that gearset pushes the shaft upward to set the preload.

 

[Rick Stephens]

I thought the prop shaft seal could be done from the outside on Alpha 1 without pulling the carrier.

You might post a pic of the groove in the shaft.

 

[tpenfield]

Is Mercruiser Alpha One Gen I lower rebuild a DIY job? . . .

For some, but not for others. It all depends on who is 'doing' it.

By comparison . . if you have experience or feel confident in doing the following things, then it is probably do-able.

Engine cylinder head rebuild
Automotive differential rebuild
Manual transmission rebuild
Full brake job on a car.

 

[spoolin01]

I thought the prop shaft seal could be done from the outside on Alpha 1 without pulling the carrier.

You might post a pic of the groove in the shaft.

Sorry, I was just blasting out my many frets before heading to the shop, and could have been clearer. The issue with this replacement drive is the vertical drive shaft. The old drive will need new seals on the propshaft as well, and possibly more.

A little knowledge, as they say.... The shop set me straight as well. Wobble is normal, that's a new one on me. The mechanic wasn't even concerned about the groove, said it didn't look that bad. He suggested setting the seal a little deeper, and I think there are a few options like that if that groove proves to be a problem.

So I went from thinking I bought a bum drive and how was I going to find some guy from craigslist that I met in a parking lot (should remember to always get the license # at least...), and that I still had 100s of $$ to spend and much more time to wait, to the prospect now that once the new water pump arrives, I can have the drive back on the boat for testing in just a day or two. All for the cost of a trip to the shop and a $17 seal. $17????

By comparison . . if you have experience or feel confident in doing the following things, then it is probably do-able.

Engine cylinder head rebuild
Automotive differential rebuild
Manual transmission rebuild
Full brake job on a car.

I've done a lot of learn-by-doing, mostly with success - rebuilt motorcycle engine and transmission, car manual transmission, outboard motor gearbox, lots of brakes, wheel bearings, and clutches, scuba regs, pneumatic spearguns, 3-stage high pressure air compressor, carburetors (not always so good there, they're a black box to me) - but have not had any formal training or apprenticing beyond what I can get from reading manuals, and now YouTube. I thought it was odd that there aren't any lower rebuild videos for the Alpha One, and having seen but not read the pages and pages in the Seloc manual about re-assembly and adjustments I wanted to see if anyone thought that was a step beyond normal "undo, then redo with new parts" kind of stuff. I don't want to have to invest in specialized gauges and whatnot either. I'm already in to the "undo" tools for $200. I don't mind the challenge, or consequences, assuming it's not a highly specialized task.

 

[achris]

If the drive is an MR or Alpha One (no preload pin in the top of the driveshaft), pull UP on the shaft and check for movement. If it's a MC-1 or R (preload pin is present in the top of the drive shaft), then push DOWN on the drive shaft and check for movement.

Chris..........

 

[spoolin01]

It's an early Alpha One - no pin, but does have the o-ring groove - so pulling up eliminates radial play, thanks.