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  1. #1

    Default How to replace a mariner 225 prop shaft

    I am new to working on outboards. I have 1 1998 Mariner 225 dfi outboard with a bent shaft that can't be straightened. I have read enough to already have the bearing casing out and all that is left is the prop shaft, the drive shaft pinion gear and the forward gear. I thought the drive shaft would come out now so I could move the clutch and parts to a new shaft. However when I try to pull out the prop shaft the shift mechanism rotates and the shaft will not come out. Is there something else holding it in on the shift shaft. Do I have to pull the drive shaft and forward gear to get the prop shaft to come out? I would appreciate any advice anyone can give me. When I look at the service manual I don't see anything holding the prop shaft in once the bearing casing is removed. I can't afford to take it to a mechanic and don't know where else to turn. Thanks in advance.
    Jerry

  2. #2
    Join Date
    Nov 2011
    Location
    tennessee
    Posts
    2,997

    Default Re: How to replace a mariner 225 prop shaft

    The driveshaft and pinion need to be removed.......
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  3. #3

    Default Re: How to replace a mariner 225 prop shaft

    Quote Originally Posted by faztbullet View Post
    The driveshaft and pinion need to be removed.......
    Thanks. Its funny that none of the service manuals can say it that way. I never have done anything like this before but am going to give it a try. I will close the post with how it goes. If you think I need any other advice please add it.
    Jerry

  4. #4

    Default Re: How to replace a mariner 225 prop shaft

    Quote Originally Posted by jluchuk View Post
    Thanks. Its funny that none of the service manuals can say it that way. I never have done anything like this before but am going to give it a try. I will close the post with how it goes. If you think I need any other advice please add it.
    Jerry
    I have run into another problem that I need help with. I still haven't been able to get the propshaft out. I was waiting for the tool needed to take off the drive shaft retainer nut which I got today. I got the driveshaft retainer nut off and also the pinon gear nut off but the driveshaft still will not come out. I cannot see anything holding it expect the bearings. Am I missing something. If the shaft is just stuck how do I get it out because I can't pull it out. Since the drive shaft won't come out I can't get the forward gear out with the propshaft. Any suggestions or help would be appreciated.

  5. #5
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    15,351

    Default Re: How to replace a mariner 225 prop shaft

    Sometimes heat around the bearing area will expand the housing so that the shaft falls out.---Use a small propane torch.

  6. #6
    Join Date
    Nov 2011
    Location
    tennessee
    Posts
    2,997

    Default Re: How to replace a mariner 225 prop shaft

    Pull out on it with steady pressure and give driveshaft several sharp raps with brass hammer. This usually releases splines from pinion gear......
    Last edited by faztbullet; 12-21-2017 at 11:34 PM.
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  7. #7

    Default Re: How to replace a mariner 225 prop shaft

    Quote Originally Posted by faztbullet View Post
    Pull out on it with steady pressure and give driveshaft several sharp raps with brass hammer. This usually releases splines from pinion gear......
    I just wanted to give an update. Fazbullet thanks for your help. I finally got the driveshaft out after it sat a few days after i spayed brake cleaner and a corrosion breaker down the drive shaft. Then the prop shaft came out. On the other unit I am fixing, the drive shaft came out easily but the prop shaft hung up on the ratcheting shift spool and broke the shift spool crank. Then the prop shaft and forward gear came out. Fortunately I have a another crank to use in the rebuild. So my next step is to put it back together with the new prop shaft. I will update and close this when is completed and tested.

  8. #8
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    4,319

    Default Re: How to replace a mariner 225 prop shaft

    You need to read the manual first before you go breaking more expensive parts. The prop shaft DOES NOT pull straight out. You have to maneuver it from the shift selector.The higher HP motors are very similiar to the Alpha lower unit and can be disassembled and assembled the same way.

  9. #9

    Default Re: How to replace a mariner 225 prop shaft

    Thanks for the information. I maybe looking in the wrong place. I have the service manual, and several online manuals that have directions on how to remove the prop shaft, drive shaft, bearing housing, shift housing, etc. and it did say to lift the prop shaft to the left to take it out. However on the install of the prop shaft it did say that you may have to move the shift lever to install it. None of this worked on taking out the bent shaft. I found out when installing the new shaft that if I faced the lower unit up when installing it and rotating the shift shaft that it went in easily. To take it out I found that when you faced the lower unit down the drive shaft would come out easily by manipulating the shift rod and the prop shaft. Not sure if the bent prop shaft may have been part of the problem. I will say the the manuals need more than just reading to do things the correct way. You need to study them, especially the pictures to see what they sometimes mean by port, starboard, forward and aft. I know what all these things are, but the manuals initial reading still confused me. In the past I have rebuilt and resealed Bravo III lower units but never worked on any outboards. I am learning about the similarities between the two. I have now got the shift shaft, drive shaft, and prop shaft installed in the lower unit. All shifting and gears work as designed. I still have to put the water pump and all the top seals and gaskets back on and then test everything. I do thank you all for the help and know your advice helped me get the job done so far.

  10. #10

    Default Re: How to replace a mariner 225 prop shaft

    Quote Originally Posted by jluchuk View Post
    Thanks for the information. I maybe looking in the wrong place. I have the service manual, and several online manuals that have directions on how to remove the prop shaft, drive shaft, bearing housing, shift housing, etc. and it did say to lift the prop shaft to the left to take it out. However on the install of the prop shaft it did say that you may have to move the shift lever to install it. None of this worked on taking out the bent shaft. I found out when installing the new shaft that if I faced the lower unit up when installing it and rotating the shift shaft that it went in easily. To take it out I found that when you faced the lower unit down the drive shaft would come out easily by manipulating the shift rod and the prop shaft. Not sure if the bent prop shaft may have been part of the problem. I will say the the manuals need more than just reading to do things the correct way. You need to study them, especially the pictures to see what they sometimes mean by port, starboard, forward and aft. I know what all these things are, but the manuals initial reading still confused me. In the past I have rebuilt and resealed Bravo III lower units but never worked on any outboards. I am learning about the similarities between the two. I have now got the shift shaft, drive shaft, and prop shaft installed in the lower unit. All shifting and gears work as designed. I still have to put the water pump and all the top seals and gaskets back on and then test everything. I do thank you all for the help and know your advice helped me get the job done so far.
    Update
    3/16/18
    Sorry it took so long to update this post but since the last time I had a lot of problems getting the prop shaft replaced and the lower unit working correctly. After I got it back together and put it back on the engine and hooked it up to the boat, the first time I shifted it the shift spool link on the end of the shift shaft broke. I had to remove it again take it all apart, wait for the parts again, and start all over. Probably the hardest part of disassembly and assembly of the prop shaft was keeping the drive shaft bearings from falling out and getting the pinion nut and washer on the drive shaft without any special tools. Needless to say I probably tried to get the nut on over 100 times before I was successful. I tightened it as best I could but was not able to use a torque wrench. Now it is all together on the boat and works fine, but the engine now has problems idling. I don't know why hitting bottom would affect how the engine runs but that is another subject which I may open another post if I can't figure it out. Thanks again to those of you that gave me advice which helped me be successful.

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