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  1. #1

    Default Alpha 1 impeller replacement question

    I have replaced impellers on my kicker motors before and it was no big deal. Now I need to change out mine on my Alpha 1 outdrive. Are there any tricks I need to know doing this? It was pretty simple on the Honda out boards.

    where is the best place to order my new impeller and find the right part number? Thanks, Kirk

  2. #2

    Default Re: Alpha 1 impeller replacement question

    The people here on Marine Engine's web site are more than happy to help and fulfill your needs. Just have your serial number for your drive handy.

  3. #3

    Default Re: Alpha 1 impeller replacement question

    Where do I find the serial number on the outdrive? Kirk

  4. #4
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    6,107

    Default Re: Alpha 1 impeller replacement question

    First identify your drive,
    Alpha One Gen 1
    or
    Alpha One Gen 2

    Gen 2 will have several bolts and nuts that hold the upper and lower together.

    Gen 1 has the two nuts inside pockets near the front of the drive. Gen 2's dont have this.



    Gen 1
    Water pump kit from this site, Also you should replace the lower pump base if it has not been replaced in a few years.

    https://www.marineengine.com/parts/m...-driveshaft-mr


    Water pump kit

    47-89984T 5

    Base

    46-44292A 3



    Gen 2

    https://www.marineengine.com/parts/m...ndard-rotation

    water pump assembly includes base
    817275Q05

    Jack
    Mass.

  5. #5

    Default Re: Alpha 1 impeller replacement question

    Quote Originally Posted by kghost View Post
    First identify your drive,
    Alpha One Gen 1
    or
    Alpha One Gen 2

    Gen 2 will have several bolts and nuts that hold the upper and lower together.

    Gen 1 has the two nuts inside pockets near the front of the drive. Gen 2's dont have this.



    Gen 1
    Water pump kit from this site, Also you should replace the lower pump base if it has not been replaced in a few years.

    https://www.marineengine.com/parts/m...-driveshaft-mr


    Water pump kit

    47-89984T 5

    Base

    46-44292A 3



    Gen 2

    https://www.marineengine.com/parts/m...ndard-rotation

    water pump assembly includes base
    817275Q05
    Thanks a bunch Kghost.... It is in fact a Gen 1 . Is it important to stay with OME quicksilver or Sierra parts? I'm seeing the same parts listed for a 1/3rd of the price on amazon. But....It looks to be a Chinese part. i dont want to cheap out and regret it. Kirk

  6. #6
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    9,273

    Default Re: Alpha 1 impeller replacement question

    I use the OEM parts for the water pump components...usually best to buy the kits

  7. #7

    Default Re: Alpha 1 impeller replacement question

    Can you buy the water pump base separately ? The kit I found is Sierra, which I’ve had good look with before. But it came without the base. Figured I’ll get it apart and check it out. The Last time it was done by a shop, and I do not know whether the base was changed out.

    Kirk

  8. #8

    Default Re: Alpha 1 impeller replacement question

    Quote Originally Posted by makomark View Post
    I use the OEM parts for the water pump components...usually best to buy the kits
    This is good advice . I found the merc/quicksilver to last a very long time, worth the price

  9. #9

    Default Re: Alpha 1 impeller replacement question

    The water pump impeller replacement was successfully accomplished. But I have an issue that concerns me. There were 3 fins completely broke off inside, and the pieces I pulled out didnít account for all three fins. I checked and cleaned out the lower intake area and found another piece, and removed the upper water intake tube and base hooked to the upper part of the outdrive, and everything was clear.

    my question is this: where could these broken pieces have gone to? Could they be sucked into my engine water jackets and clog something up? How can I check this out?

    the motor was ran at 3000 rpms underway for 10- 15 minutes after it first overheated. The remaining 3 fins of the impeller pumped enough water to keep the engine at normal operating temp at higher rpms. Kirk

    here is a photo of the damaged impeller.

    https://photos.app.goo.gl/gP4WDg2ecoyNw1bm7
    Last edited by kirkll; 09-30-2022 at 11:36 AM. Reason: Add photos

  10. #10
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    9,273

    Default Re: Alpha 1 impeller replacement question

    The piece went "downstream"...usually as much smaller pieces than you recovered. they could be in the block or the water-cooled exhaust components. The only way I know to make sure they didn't take up residence 'inside' is to look. That said, they are more likely to wind up at the restrictions - the smallest one being the elbows. As a rule, they don't usually cause problems in the block or the manifolds.

  11. #11

    Default Re: Alpha 1 impeller replacement question

    Quote Originally Posted by kirkll View Post
    The water pump impeller replacement was successfully accomplished. But I have an issue that concerns me. There were 3 fins completely broke off inside, and the pieces I pulled out didn’t account for all three fins. I checked and cleaned out the lower intake area and found another piece, and removed the upper water intake tube and base hooked to the upper part of the outdrive, and everything was clear.

    my question is this: where could these broken pieces have gone to? Could they be sucked into my engine water jackets and clog something up? How can I check this out?

    the motor was ran at 3000 rpms underway for 10- 15 minutes after it first overheated. The remaining 3 fins of the impeller pumped enough water to keep the engine at normal operating temp at higher rpms. Kirk

    here is a photo of the damaged impeller.

    https://photos.app.goo.gl/gP4WDg2ecoyNw1bm7
    Usually they get caught in the ps cooler. Can take the inlet hose off there and back flush from thermostat housing, or take drive off and backflush from thermostat housing.

  12. #12
    Join Date
    Dec 2006
    Location
    Greenfield Me. USA
    Posts
    6,362

    Default Re: Alpha 1 impeller replacement question

    Quote Originally Posted by Dieter View Post
    Usually they get caught in the ps cooler. Can take the inlet hose off there and back flush from thermostat housing, or take drive off and backflush from thermostat housing.
    Ayuh,..... Usually any broken impeller bits get caught in the P/S cooler, or the t-stat housin',.....
    Any Grease is Better,... Than No grease at All....

  13. #13

    Default Re: Alpha 1 impeller replacement question

    Quote Originally Posted by makomark View Post
    The piece went "downstream"...usually as much smaller pieces than you recovered. they could be in the block or the water-cooled exhaust components. The only way I know to make sure they didn't take up residence 'inside' is to look. That said, they are more likely to wind up at the restrictions - the smallest one being the elbows. As a rule, they don't usually cause problems in the block or the manifolds.
    Thanks .... I feel a bit better knowing that. I was surprised that the impeller only lasted a couple years after being replaced by a reputable shop. I'm assuming they used OEM parts, or at least sierra. Probably be a good idea to replace these every two years as routine maintenance eh?

    Kirk

  14. #14
    Join Date
    Dec 2006
    Location
    Greenfield Me. USA
    Posts
    6,362

    Default Re: Alpha 1 impeller replacement question

    Quote Originally Posted by kirkll View Post
    Thanks .... I feel a bit better knowing that. I was surprised that the impeller only lasted a couple years after being replaced by a reputable shop. I'm assuming they used OEM parts, or at least sierra. Probably be a good idea to replace these every two years as routine maintenance eh?

    Kirk
    Ayuh,.... Correct,......

    Though I have used Globe, run-dry, blue rubber impellers, that last, 'n last,....
    Expensive, but they hold up really well, for a long time,....
    Any Grease is Better,... Than No grease at All....

  15. #15

    Default Re: Alpha 1 impeller replacement question

    How would i cross reference a globe impeller part number for my 1990 Alpha 1 , Gen one ? I did some research on those and that would be a worth while investment me thinks.... Kirk

  16. #16
    Join Date
    Dec 2006
    Location
    Greenfield Me. USA
    Posts
    6,362

    Default Re: Alpha 1 impeller replacement question

    Quote Originally Posted by kirkll View Post
    How would i cross reference a globe impeller part number for my 1990 Alpha 1 , Gen one ? I did some research on those and that would be a worth while investment me thinks.... Kirk
    Ayuh,.... At the Globe website,..... I believe the number is 1000,......
    Any Grease is Better,... Than No grease at All....

  17. #17

    Default Re: Alpha 1 impeller replacement question

    Well that wasn’t very helpful…. I did find the website, and all they listed under Mercruiser is model numbers. I have no idea what the model number or serial number is for this 1990 gen 1 . It’s not stamped into the drive anywhere I’ve seen…

    I was hoping for some guidance….

    Kirk

  18. #18
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    9,273

    Default Re: Alpha 1 impeller replacement question

    if you go here:
    Find the Right Impeller (globemarinedirect.com)
    they have a lookup function.

    enter impeller, mercruiser, and the mercruiser part number for the last impeller your bought. And it should confirm the number given.

    they also have a couple other cross references available.

    Worst case, send them a message from their contact page...


    47-89984T 5

  19. #19

    Default Re: Alpha 1 impeller replacement question

    This is how you can help yourself...

    look up the impeller part number on our hosts parts site https://www.marineengine.com/parts/m...-driveshaft-mr

    impeller is #35- Part 47-89984T4 or Sierra 18-3017

    globe has a find the right impeller - chose mercruiser put the part number listed for #35...

    leads you to this page which is the same part Bondo directed you to https://www.globemarinedirect.com/pr...01-12-1590.htm

    not sure if this is only for distributors here it is on ebay https://www.ebay.com/itm/223113366596

    If you look at bottom of both ebay and globe site the merc and sierra parts are listed.



    This site has some of the best parts breakdowns out there you can get to it by clicking boat engine parts on upper left header of this page....

  20. #20

    Default Re: Alpha 1 impeller replacement question

    Thanks for the help guys.... It's appreciated. After only getting 2 years out of the last impeller that was replaced, I think the higher quality Globe impeller would be the way to go. Kirk

  21. #21

    Default Re: Alpha 1 impeller replacement question

    Quote Originally Posted by kirkll View Post
    Thanks for the help guys.... It's appreciated. After only getting 2 years out of the last impeller that was replaced, I think the higher quality Globe impeller would be the way to go. Kirk
    Was that an OEM merc impeller that lasted only 2 years or aftermarket?

    The OEMs tend to last much longer. Its been a few years since I had a Gen 1 but if I recall the sierra didn't last but 2-3 years, OEM merc was at least double it. The newer Gen 2 has a much better impeller they tend to forever...Changed my neighbors 10 year old one was in perfect shape, did mine after 6 seasons again perfect . Worth the extra $30 vs aftermarket

  22. #22

    Default Re: Alpha 1 impeller replacement question

    I'm not sure what they put in it last time. I took it to a shop that typically doesn't work on older boats. ( i use a different shop now for bigger projects) The reason i took it to the shop instead of doing the impeller myself the first time was that it had been many years prior that it had been opened up according to the previous owner of the boat. So i was thinking i'd let the shop break it loose for me the first time so i wouldn't have a hard time getting it apart the next time.

    The one i just installed was a sierra. Hopefully i'll get a couple years out of it, but think i'll order a new one to have on hand in my shop just in case. It was a fairly simple procedure to do.... But i had a bit of an issue with it popping out of gear and getting it back together. Next time i'll make sure its in forward gear before i pull the lower unit, and keep the prop on it....

    I screwed up and pulled it loose before putting it in gear, and had to mess with turning the shift cam to the forward position (Clock wise) and lining up the shift arm. I also learned about keeping pressure on the prop while trying to getting the spline lined up kept it from popping out of gear.... I'll use a bungee strap next time.............Live and learn eh?

    Kirk

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