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  1. #1
    Cadet
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    Jul 2010
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    Illinois
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    Default how to check for bad impeller

    99 mercruiser 3.0 woundering how you can tell or check to see if the impeller is bad. Thanks

  2. #2
    Petty Officer 2nd Class
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    May 2010
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    109

    Default Re: how to check for bad impeller

    I suspect the answers you will get is if you haven't replaced it in 2 years, its bad, replace it.

    If you are running hot, its bad replace it.
    1997 SeaRay 175
    3.0LX Mercruiser
    Alpha 1 Gen 2

  3. #3
    Cadet
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    Illinois
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    Default Re: how to check for bad impeller

    i just bought the boat so i am not sure if it has been replaced or not but engine is not running hot. i have just been seeing alot of post talking about them thought i might want to check to see if mine is working. How hard are they to change and how expensive are they?

  4. #4
    Captain
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    Mar 2009
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    Western NY
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    Default Re: how to check for bad impeller

    Quote Originally Posted by cmanion View Post
    i just bought the boat so i am not sure if it has been replaced or not ......
    It is a good idea to replace it. Then you will know.
    Terry
    87, 4WINNS H 190
    470/Alpha I

  5. #5
    Ensign
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    Jun 2010
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    South Metro, MN
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    996

    Default Re: how to check for bad impeller

    They're not terribly expensive, a relative bargain compared to the expense that ignoring them will cause.

  6. #6
    Senior Chief Petty Officer
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    Jun 2010
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    So. Cal
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    Default Re: how to check for bad impeller

    You pull it off, install a new one and consider it checked. An impeller isn't something to inspect. Change it yearly and have no worries.

  7. #7
    Master Chief Petty Officer Blk-n-Blu's Avatar
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    May 2004
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    Pocono Summit Pa.
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    819

    Default Re: how to check for bad impeller

    Have a look at this link, think you might need it soon:
    http://www.mercstuff.com/howdoi.htm

  8. #8
    Petty Officer 2nd Class
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    Jul 2008
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    SE Wisconsin
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    190

    Default Re: how to check for bad impeller

    There is no way to inspec the impeller without removing it. A bad impeller will have pieces missing. Like others have said, if you are unsure how old it is, it is a good idea to replace it. The problem is that an old impeller might look ok, but can go bad soon after.

  9. #9
    Petty Officer 1st Class Brentathon's Avatar
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    Dec 2009
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    Long Island, NY
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    368

    Default Re: how to check for bad impeller

    I just spent $700 and 12 hours of work on my overheating issue, to eventually find out that my NJEW impeller was the cause of a flow which was too low to sufficiently cool my engine. The Sierra brand impeller was defective, and I'm currently in the process of sending it back to Sierra for a warranty claim.
    I think I will change my impellers EVERY YEAR now, instead of every 2 years, like I have been.

  10. #10
    Senior Chief Petty Officer
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    Jun 2010
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    So. Cal
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    Default Re: how to check for bad impeller

    They are cheap. If you are a decent wrench you can do it yourself in a couple of hours.

  11. #11
    Senior Chief Petty Officer
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    May 2007
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    721

    Default Re: how to check for bad impeller

    it only takes me 15 minutes on my Cobra

  12. #12
    Petty Officer 2nd Class
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    Jul 2008
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    104

    Default Re: how to check for bad impeller

    Quote Originally Posted by Dakota47 View Post
    it only takes me 15 minutes on my Cobra
    piece of cake on a cobra. On a Merc you have to take the lower unit off... a lot more work and seals to replace

  13. #13
    Petty Officer 1st Class
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    Oct 2009
    Location
    West Columbia, SC
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    248

    Default Re: how to check for bad impeller

    At risk of beating the horse, I would definitely go ahead and replace it. I would say keep the old one as an emergency spare if it still looked good, but apparently an "on-the-water" swap is not possible with your merc (based on above post).

    My VP impeller is right at the front of the motor...16 screws gets the bench seat loose, and another four gets me into the impeller housing.

    My old one will at least get me to shore in a pinch.

    Better yet, sell your old one on eBay as "slightly used"...some poor sap who doesn't frequent iBoats will buy it...

    I'm kidding, of course.
    2007 Stingray 180RX VP 3.0 GLP-E SX-A Pulled by a 2007 Chevy Tahoe 5.3L

    "stupidity is usually painful and expensive, as it should be"
    Actual quote from my boss, "You have no idea who I think I am!"

  14. #14
    Cadet
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    Jul 2010
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    Illinois
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    Default Re: how to check for bad impeller

    Thanks for all the input I am going to order my replacement tom. and put it in I would much rather be safe than sorry. Thanks again, Chris

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