Crack in lower drive assembly and I need some help in identifying this sterndrive

mynorac

Cadet
Joined
Jun 27, 2014
Messages
22
I bought an old (1969) boat a few years ago and have had it in the water a few times. When I went to get the boat I noticed that the lower part of the sterndrive had a crack in the forward part of the gear housing. This is a very old boat that I got for little money and I don?t want to invest much into it. I know very little about boats but I?m pretty good at do-it-yourself projects. This 1969 Sabre Craft is equipped with a 120hp 4 cylinder engine. The upper portion of the sterndrive is labeled Mercruiser 120/140hp and the serial number may be 2791168 but is very hard to read. I really could use some help identifying this model sterndrive if I have to purchase parts. See pics. I did remove the lower drive assembly and inside it has the number 1623-5412. When I removed the lower drain plug a bunch of water came out with the oil. I think this may have caused the crack. My question is, can this unit be repaired? One thought is to try to pump cleaning solutions into the drain hole then using something like JB weld. After reassembly running and flushing the lower unit with good oil several time before a trip to the lake. My other thought is to completely disassemble the lower unit and weld the crack. The second choice is the best but it looks like I might need special tools. Any other ideas? Sorry about all the posting questions I had before - I was trying to post in this forum but was unaware of the minimum of three text posts before being able to upload photos - Thanks to all of you who helped me thru this posting issue!
 

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yjanray

Petty Officer 1st Class
Joined
Jul 30, 2009
Messages
257
I would buy an SEI unit....trust me, its a huge pain in the butt to try and take the lower unit apart without the right special tools (which cost big $$$)
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,365
I agree, a later model drive will bolt up, the 8 spline lower is rare as can be , newer are 13 spline and you just cant install a newer later model lower on your upper
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,148
Ayuh,.... That lower had water in it, in the winter time,....

I agree, the coarse spline lower is tough to find to match that upper,...
I'd scrap the whole thing, 'n go to a newer replacement,...

Newer MC-1s, 'n Alpha 1s bolt right on,....
Just use the shorter input shaft,....
 

mynorac

Cadet
Joined
Jun 27, 2014
Messages
22
I agree, a later model drive will bolt up, the 8 spline lower is rare as can be , newer are 13 spline and you just cant install a newer later model lower on your upper

Sorry but I don't understand. By 8 spline your mean the number of slots on the shaft that fits into the upper assembly. If that is correct then the upper female assembly is match to accept only 8 spline so how can a more modern spline shaft fit? I know that you are correct but I just don't understand?
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,365
A complete drive will bolt up to the transom , you cant mix just the lower units
 

kenny nunez

Captain
Joined
Jun 20, 2017
Messages
3,351
If you get a new or newer than the one you have check the distance between the 4 top mounting studs on the bell housing. Sometime after 69 the distance was widened slightly and you will have to elongate the top 4 holes on the drive unit.
 
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mynorac

Cadet
Joined
Jun 27, 2014
Messages
22
No Title

Well I got everything torn apart and had the crack welded. Just waiting for some new seals and gaskets and I will start reassembly. In my opinion all the gears and bearings are in good condition.
 

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