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  1. #1
    Petty Officer 3rd Class
    Join Date
    Apr 2009
    Tolland county CT

    Default Drive shaft and shift shaft frozen in the lower unit 9.8

    Hi, At my shop i mostly work on Johnson and Evinrudes (good stuuf) but this guy braught in a merc for me to see if i could get her going. He said it was seized. After about 20 mins i diagnosed that it wasnt the powerhead that weas seized. I've had this problem with a few mercs that i baught for parts before. So i take it apart and like i assumed the drive shaft and the shift shaft are both nice and rusted and seized (Gotta love them high quality merc parts) So besides getting a new lower unit is there any possibility that this lower unit will be savable. Im thinking about hooking up some vise grips to them and see if i can break them free. Im still trying to understand why a company would use s#!t metal on something that is going to be wet for most of the time.

  2. #2
    Admiral Chinewalker's Avatar
    Join Date
    Aug 2001
    1000 Islands, NY

    Default Re: Drive shaft and shift shaft frozen in the lower unit 9.8

    If the shafts are savable (.ie not completely pitted at the seal points) you might be able to get by with replacing all the needle & ball bearings in the unit. Some folks have even used stainless SpeediSleeves to get new seal area on pitted shafts. All depends on how much time and effort you want to put into it... and whether the gears are salvageable. Won't know until you get it apart to see exactly how bad it is...
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  3. #3
    Petty Officer 2nd Class
    Join Date
    Feb 2012
    England, uk

    Default Re: Drive shaft and shift shaft frozen in the lower unit 9.8

    "good stuff" lol. Got some nerve posting that on the Mercury forum lol

    Anyway, by the sounds of it gearbox is shot and its probably not even worth salvaging if its siezed in there tight. I would personally bin it and try to get hold of a decent second hand gearbox instead. Chances are if the engine ain't frozen it will be o.k (and out perform any equivilent omc ).

    Sounds like it's been negleted for a long time though and you might well find there are other issues with it too. Any by the way, I agree with you, it's beyond me why the earlier Kiekhaefer/Mercury engineers designed such brilliant engines but stumbled at the last hurdle and equipt them with rubbish driveshafts. Pretty daft I know. They were undoubtely Mercury's "achillies heels" .

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