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  1. #1
    Seaman
    Join Date
    Aug 2001
    Location
    South Alabama
    Posts
    53

    Default Alpha 1 impeller replacement

    Not sure when the water pump impeller was last changed on my 89 5.7L Mercruiser w Alpha 1 outdrive, so I'd feel better replacing it. Having never done this on an I/O, need any tips you guys may have. The marina mechanic says rather than just removing the lower unit, they remove the whole outdrive. Why in the world would they do that??? Also, the two nuts fastening the front of the lower unit look like a closed end wrench won't get in there. Is there a special wrench made for this? Any advice is greatly appreciated. I have a shop manual and heat for stubborn bolts/nuts. Thanks!

  2. #2
    Petty Officer 2nd Class
    Join Date
    Jul 2001
    Location
    u.s.a.
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    136

    Default Re: Alpha 1 impeller replacement

    gadoo! I can help you. Your out drive splits into and you don't have to pull the full outdrive to change the impeller. The marine mechanics are trying to take you and don't let that happen. First on each side of the lower unit on the out drive there is two nuts on each side 5/8th 4 all together. Loosen them as much as possible. Then there is a 5/8th nut in the front of the out drive opposite of the prop but at about the same highth of the last 4 nuts that you have loosened. Then you have the tork tab that you loosen it is the pointed looking thing above the prop and sometimesis just round, just remember this is above tour prop maybe an inch. Remove that tab Uasully big allen wrech and you have to go trough the hole above the tork tab to remove this allen screw. Then after removing the tork tab there is an allen srew on the bottom side of that. Remove that allen screw and your unit is ready to drop and replace the water pump.Then reverse the way of putting it on the way you took it off. The best way of doing this is with the shift handle in forward. To be shure of that put the shift handle in forward go to the prop spend the prop clockwise and it will ratchet counter clockwise it will lock .Then Split the lower that is the easiast way to do it. If you kick the lower out of forward, on the front side of the lower unit when it is split there is a spline opposite of the prop. This splin is 9mm turn it clockwise slightly and that is very slightly to get back in forward.Good luck and I hope this helps!Nick

  3. #3
    Fleet Admiral 12Footer's Avatar
    Join Date
    Mar 2001
    Location
    Lehigh Acres, FL, USA
    Posts
    8,233

    Default Re: Alpha 1 impeller replacement

    Wow.How can you add to perfection? Nickster, that was excellent. I learned two things that will save me much grief in the future (if I EVER werk on a friend's Alpha aain as long as i live). But Gadoo, do get the shop manual for reference. It will pay for itself in due time.BTW, I am not badmouthing Alpha drives at all. They are just new to me.
    "Did you hear about the guy whose whole left side was cut off? He's all
    right now."

  4. #4
    Seaman
    Join Date
    Aug 2001
    Location
    South Alabama
    Posts
    53

    Default Re: Alpha 1 impeller replacement

    Nickster & 12 Footer...I picked up the kit yesterday. I'll post the results after I get finished. Nickster, thanks for the step by step....sounds like it's right out of a manual.

  5. #5

    Default Re: Alpha 1 impeller replacement

    Quote Originally Posted by nickster View Post
    gadoo! I can help you. Your out drive splits into and you don't have to pull the full outdrive to change the impeller. The marine mechanics are trying to take you and don't let that happen. First on each side of the lower unit on the out drive there is two nuts on each side 5/8th 4 all together. Loosen them as much as possible. Then there is a 5/8th nut in the front of the out drive opposite of the prop but at about the same highth of the last 4 nuts that you have loosened. Then you have the tork tab that you loosen it is the pointed looking thing above the prop and sometimesis just round, just remember this is above tour prop maybe an inch. Remove that tab Uasully big allen wrech and you have to go trough the hole above the tork tab to remove this allen screw. Then after removing the tork tab there is an allen srew on the bottom side of that. Remove that allen screw and your unit is ready to drop and replace the water pump.Then reverse the way of putting it on the way you took it off. The best way of doing this is with the shift handle in forward. To be shure of that put the shift handle in forward go to the prop spend the prop clockwise and it will ratchet counter clockwise it will lock .Then Split the lower that is the easiast way to do it. If you kick the lower out of forward, on the front side of the lower unit when it is split there is a spline opposite of the prop. This splin is 9mm turn it clockwise slightly and that is very slightly to get back in forward.Good luck and I hope this helps!Nick
    hi Nick my husband and i have a 140hp mericrusier in/outboard he did exactly what you told this man to do and replaced the waterpump on the bottom half of sterndrive and now he cant get it to go back on please any help would be greatly appreciated thanks jody

  6. #6
    Petty Officer 3rd Class
    Join Date
    Jul 2010
    Location
    Los Angeles County California
    Posts
    92

    Default Re: Alpha 1 impeller replacement

    Most likely the driveshaft splines aren't aligned. If the lower unit and control are in foreword gear, turn the prop while pushing in and it should go.

  7. #7
    Moderator JB's Avatar
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    The Hideout, Whitt, TX, USA
    Posts
    45,903

    Default Re: Alpha 1 impeller replacement

    NINE YEAR OLD thread!! You need to make your own, new one.

  8. #8
    Petty Officer 3rd Class
    Join Date
    Jul 2009
    Posts
    98

    Default Re: Alpha 1 impeller replacement

    Nine year old thread! Too funny! Sounds like you are fighting the shifter cable bracket on the lower unit. The first thing you have to do is make sure that the shifter lever is in full forward position and that the shifter cable bracket on the lower end is pointing straight forward towards the bow. Please make a new thread though!
    1994 Sea Ray 230 DA
    5.7L Mercruiser
    Alpha One Gen II

  9. #9
    Petty Officer 2nd Class
    Join Date
    Jul 2008
    Posts
    104

    Default Re: Alpha 1 impeller replacement

    really good info here on this

    http://mercstuff.com/waterpumpinst.htm

  10. #10
    Master Chief Petty Officer bigskiohio's Avatar
    Join Date
    May 2008
    Posts
    876

    Default Re: Alpha 1 impeller replacement

    lot easier on the bench not ont he boat plus you can check some other maintenance items
    1973 Starcraft Supersport
    120 mercruiser 153c.i.

  11. #11
    Petty Officer 2nd Class
    Join Date
    May 2010
    Posts
    109

    Default Re: Alpha 1 impeller replacement

    Quote Originally Posted by JB View Post
    NINE YEAR OLD thread!! You need to make your own, new one.
    I think this has got to be a record! I didn't even know the internet was around 9 years ago
    1997 SeaRay 175
    3.0LX Mercruiser
    Alpha 1 Gen 2

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