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  1. #1
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    Smile mercruiser water pump

    Hi I am new here and new to I/O boats. I have an 85 alpha one mercruiser with a 350 chevy motor. My question is that since the motor has a water pump just like in a car is there another water pump in the out drive. I am having trouble getting it to pump water with water hooked up to the out drive just like i used to do on outboard motors with a motor flush hooked to a hose. Any help would be greatly appreciated.

  2. #2
    Moderator Bond-o's Avatar
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    Default Re: mercruiser water pump

    Ayuh,.. Welcome Aboard,...

    Yes,.. The pump you see is just a recirculating pump,...
    The Raw water pump is the Impeller pump mounted to the top of the Lower Unit...

    Head on up to the Adults Only section,+ dig up the factory service manuals for your drive,+ motor,...
    It's all explained in the manuals..
    Any Grease is Better,..... Than No Grease at All.......

  3. #3
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    Default Re: mercruiser water pump

    thanks for the quick respone i appreciate it. It helped alot. Should these take water with a hose just like outboards or do the actually need to be sumerged in water to pump?

  4. #4
    Seaman Apprentice
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    Default Re: mercruiser water pump

    yes they should work fine with the hose. i have the same lower unit in my boat and just had the same problem. if you read some of my threads you will understand. the impeller is a simple job as long as you go by the book. this blog is amazing! use it! good luck!

  5. #5
    Chief Petty Officer
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    Smile Re: mercruiser water pump

    hi there here a couple of links

    http://www.youtube.com/user/TcElectronicsMarine

    http://www.mercstuff.com/

    looks like you need a new impeller in your drive pump, not very hard to do just take your time and read the instructions...

  6. #6
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    Default Re: mercruiser water pump

    Thanks everyone for the info it has been great help. I installed a new water pump today and have one more question. What is the best way to tell if the engine is getting enough water? I know this probably sounds like a dumb question but after I installed it, it is still acting about the same. After running about 10 min. with hose hooked to lower unit my temp gauge reads about 170 and the motor seems a little warmer than I expect. After I turn it off I can take a water hose loose from engine and not alot of water in them like i would expect. I don't know if my temp gauge is reading right cause I was told if there is not enough water in engine that it would not read right. Does anyone think I still have a problem or just over paranoid. Too much money invested to burn it up now.

  7. #7
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    Default Re: mercruiser water pump

    Quote Originally Posted by eande View Post
    My question is that since the motor has a water pump just like in a car...
    It may look like a automotive water pump, but it is constructed different. The marine water pump on your engine will (should) have a brass impeller instead of a steel impeller, so it dosn't rust out from exposure to fresh/saltwater.

    You said you changed the water pump, was this the recirculating water pump on the engine or the raw water pump (impeller) in the outdrive?

  8. #8
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    Default Re: mercruiser water pump

    Thanks everyone I got my water pump problem fixed. Seems after taking it back apart that I missed the water tube into guide tube while putting it back together. I have one more question though could someone explain the procedure to adjust shifting cable. It don't want to engauge all the way.

  9. #9
    Moderator Bond-o's Avatar
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    Default Re: mercruiser water pump

    I have one more question though could someone explain the procedure to adjust shifting cable. It don't want to engauge all the way.
    Ayuh,.... The lower shift cable probably needs Replacing.....
    Did you read This,.... That's where the Answers are...
    Head on up to the Adults Only section,+ dig up the factory service manuals for your drive,+ motor,...
    It's all explained in the manuals..
    Any Grease is Better,..... Than No Grease at All.......

  10. #10
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    Default Re: mercruiser water pump

    I looked up th e manual for my boat and have another question. When you refer to the lower shift cable do you mean the bottom one on the top of the motor or are you refering to something in the outdrive. I tried to adjust my cable and got my forward back but no reverse. Your information in invaluable to me I appreciate it.,

  11. #11
    Moderator Don S's Avatar
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    Default Re: mercruiser water pump

    When you refer to the lower shift cable do you mean the bottom one on the top of the motor or are you refering to something in the outdrive
    The cable that goes from the engine shift bracket to the outdrive.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  12. #12
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    Default Re: mercruiser water pump

    Ok thank you very much.

  13. #13
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    Default Re: mercruiser water pump

    Did it work before you put the pump in? when you take the lower unit off it must be in forward gear. You may have missed the shift arm.
    putting it together.

  14. #14
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    Default Re: mercruiser water pump

    Yes it seemed to work fine before I replaced the water pump. But I got my forward back just no reverse.

  15. #15
    Chief Petty Officer
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    Thumbs up Re: mercruiser water pump

    this is what happen you missed the shift arm you have to take it apart again, is better is someone is helping you!!!

  16. #16
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    Default Re: mercruiser water pump

    Not really what I wanted to hear but thanks alot for the info. I was getting ready to buy shift cable.

  17. #17
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    Default Re: mercruiser water pump

    I have yet another question. I tried adjusting my lower shift cable like the manual said. I can gat one gear but not the other. I adjust it back and get good forward and I can adjust it up and get good reverse. But there does not seem to be any between that I can get both gears solidly. Any ideas?

  18. #18
    Moderator Don S's Avatar
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    Default Re: mercruiser water pump

    Time for a new cable, it's worn out inside the cable, that causes too much slop and not enough cable movement at the shifter.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  19. #19
    Rear Admiral Fishermark's Avatar
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    Default Re: mercruiser water pump

    Did yo buy a new cable or are you still using the old cable? If you are reusing the old cable, does it operate smoothly? Disconnect it at the engine and manually push and pull the cable while someone turns the prop. (Engine off of course. ) If you can easily and smoothly move the cable and the outdrive goes into reverse and forward then it may just be your adjustment. Post your results and let us know.

    Better yet would be to start a new post with this issue.

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