alpha lower unit

[ack grounded]

1990 merc 4.3 L with a Alpha One drive

went out for last ride of the season and just humming along - headed back to dock and @ slow rpm hit a rock
sheared off skeg, and made a 3 blade prop a 2 blade prop.

limped back to dock which was close at very low rpm as possible.
examined prop which spun easy and was not bent


ok what is the best direction at this point...
explore a alum weld - only about 1" left on skeg
replace lower unit
buy lower shell only and swap out

 

[jaxnjil]

Re: alpha lower unit

they make a stainless steal cover that fits over your skeg. i had one on one of my boats when i bought ie. it screwed on at the top of the skeg and was called skeg guard. i think 1 inch would be enough left to hold one. you could allso have a welder weld a new one on.
make sure you turn the shaft slowly with no prop and make sure you didnt bend the shaft

 

[ziggy]

Re: alpha lower unit

i think i'd wanna put a micrometer ontoit. the prop shaft that is. just to make sure there's no run out. was that 2 blade prop stainless or aluminum? aluminum i hope.... aluminum us more forgiving in a prop strike situation...
as for the skeg. i understand they don't do much, for the most part, on an i/o. other than protecting the prop..... if ya got the meat, the skeg gaurd sounds good to me. if not. a good welder can do ya right. or go w/o. and don't go shallow......

if ya had a ss prop. more investigation i'd think would be in order...

 

[chiefalen]

Re: alpha lower unit

Do a search for 45 auto. He just did his.

 

[ack grounded]

Re: alpha lower unit

i wish i had 45 auto as a neighbor. beautiful job.

i guess getting a weld on skeg is the way to go - about $200 +/- ?

swapping with a new lower unit is $800 plus labor
swapping with new unit housing is $300 plus labor - special tools, possible shimming etc.

 

[jaxnjil]

Re: alpha lower unit

here is the link for the skeg guard her on i boats. no pics.

http://www.iboats.com/Keelguard_Ske...5797073--**********.137876175--view_id.259073



still--make sure-- you didnt bend prop shaft. thats a pretty hard hit to knock off the skeg and one of the prop blades

 

[Chris1956]

Re: alpha lower unit

Ack, I did the same on my Mercury outboard. Merc sold me just the skeg which I had a welder install. At the time (20 years ago) the skeg was $16 and the welding was $60. The welder installed the skeg without disassembling the gearcase, and did not melt any of the seals.

 

[ack grounded]

Re: alpha lower unit

how does one weld without damaging the seals internally?
the skeg and housing must get very hot to weld . should it be disassembled first? Is there a certain welding machine used? One uses less heat than another.
if so, what special tools are needed?

the more knowledge i have, i can make sure i have the right welder

 

[Chris1956]

Re: alpha lower unit

Ack, I cannot answer any of your questions. Most of the welders I talked to wanted me to strip out all the gears and seals. The welder I hired said it wasn't necessary, and he was correct. I will guess he used some sort of heat sink on the gearcase. He probably used a heliarc welder since the newer kinds of welders may not have been invented.

This guy had experience with outboards, and other marine machinery

 

[ack grounded]

Re: alpha lower unit

chris1956,
fair enough, I assume the oil would help as heat sink but not sure if that is enough. I will investigate further -
Would removing the gears involve special tools?

 

[Chris1956]

Re: alpha lower unit

Removing the gears does involve special tools. It can be a real PIA to get the bearing carrier out, especially if the OD is older and has normal corrosion.

I would not think it would be too difficult if you had the special tools and some experience since you do not have to actually repair/replace any of the gears shims.

 

[J JACKSON]

Re: alpha lower unit

i welded my skeg back on with a spool gun on a mig welder and i didn't dissemble it i just welded about 1/4 inch at a time and let it cool it took a few hours but i would weld some then go do something else and let it cool. i haven't had any problems with it and that was at the beginning of the summer.