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Mercruiser - Upper Unit replacement Compatibility-gctid403123

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    Mercruiser - Upper Unit replacement Compatibility-gctid403123

    To all the fantastic forum techies out there:

    My dad has a 1971 starcraft with the 4 cylinder GM engine (120 hp), transom plate serial# 2649894 There is some debate about how it happened, but lets suffice it to say that the outdrive was run without sufficient oil and the upper gears are shot (pulled the top plate and the gears are just rounded off). There was some oil in the lower unit and while I haven't checked it, there doesn't seem to be an issue there atm (of course I understand the problem of metal fragments getting down there).

    I've contacted allamericandriveservice.com and they are quoting about 1500 to do a complete rebuild of the outdrive, but I was also looking at the cheaper alternative of just swapping a used upper unit.

    I was looking at ebay and there are several "used" uppers on there for various model mercruisers, and in navigating the lingo for various mercruiser models I just got hopelessly confused. What do I need to look for to know if a particular upper is compatible with this lower unit/ transom shield?

    I'd also appreciate any recommendations if anyone has any for rebuilds that might be less expensive (but still good quality) other than the above mentioned. I'm located in Syracuse, NY for reference.

    Thanks in advance, I hope everyone is having a great boating season!

    John R.

    #2
    JohnR wrote:
    To all the fantastic forum techies out there:

    My dad has a 1971 starcraft with the 4 cylinder GM engine (120 hp), transom plate serial# 2649894 There is some debate about how it happened, but lets suffice it to say that the outdrive was run without sufficient oil and the upper gears are shot (pulled the top plate and the gears are just rounded off). There was some oil in the lower unit and while I haven't checked it, there doesn't seem to be an issue there atm (of course I understand the problem of metal fragments getting down there).

    I've contacted allamericandriveservice.com and they are quoting about 1500 to do a complete rebuild of the outdrive, but I was also looking at the cheaper alternative of just swapping a used upper unit.

    I was looking at ebay and there are several "used" uppers on there for various model mercruisers, and in navigating the lingo for various mercruiser models I just got hopelessly confused. What do I need to look for to know if a particular upper is compatible with this lower unit/ transom shield?

    I'd also appreciate any recommendations if anyone has any for rebuilds that might be less expensive (but still good quality) other than the above mentioned. I'm located in Syracuse, NY for reference.

    Thanks in advance, I hope everyone is having a great boating season!

    John R.
    My friend has a boat that he is parting out.

    This Alpha drive is available, don't believe it has touched water since being redone.

    I could deliver it to the border at Waterdown if necessary.

    I think $850 would buy it but will have to check. It is attached to a 4 cylinder at the moment.

    Attached files http://baylinerownersclub.org/media/....jpg[/img]

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      #3
      Thanks for the suggestion Check737! Always sorry to see a boat get parted out... but I could definitely give the drive a new life, especially if it's a drop-in replacement, and it looks to be in good shape.

      What I am not sure about though is that this drive would be compatible with the older transom shield / engine? The Alpha's are a much newer drive (started production in '83). I had read that the shift throw on the 1974 and newer drives are a "long throw" and are not compatible with '73 and earlier drives.

      I believe there may be a difference in the length of the splined yoke as well? (the older ones being shorter), but i can't seem to find specifics on what years are what. I will probably pull the drive this weekend and see if I can measure the yoke.

      John

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