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Separating Lower Unit

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  • Separating Lower Unit

    (My first post on this forum) I do the maintenance on all of the 4HP outboards for my sailing club. When changing a water pump impeller, there are two bolts that are removed on the lower unit, and then the whole lower unit (including the drive shaft from the power head) should easily slide out. However, on occasion, I have encountered a problem when the spline connection between the drive shaft and the power head is completely frozen. In order to try to separate them, I have gone so far as to hang the motor upside down supported by wooden clamps on the drive shaft, and then trying to "shock" the motor loose by using the weight of the power head (didn't work). I have also tried a slide hammer. Do any of you have suggestions on how to separate a super-stubborn spline connection?