Please note this thread has been inactive for 90 days. For the best results, please start a new thread.
Results 1 to 8 of 8
  1. #1

    Default Mercruiser - test for bad impeller?

    Is there a way to test for a bad impeller on the outdriver? 1985 170hp, alpha 1 I believe.It hasn't been run in over a year and I'm curious if I should spend the time and money to replace the impeller or if it's not warranted. With a hose hooked up and ilding it in my driveway, it doesn't go over 170degrees...

  2. #2
    Lieutenant Junior Grade
    Join Date
    Mar 2002
    Location
    Colorado
    Posts
    1,116

    Default Re: Mercruiser - test for bad impeller?

    reolace it and change the drive oil, grease the U joints and have the drive pressure tested.

  3. #3
    Petty Officer 2nd Class llerrad's Avatar
    Join Date
    Jan 2003
    Location
    Ontario, Canada
    Posts
    172

    Default Re: Mercruiser - test for bad impeller?

    For the cost to replace, just do it, the cost of damage not worth it. The impeller will dry and blades will come off. Many say change ever one or two years.
    Cams and Carbs no Sails here

  4. #4
    Petty Officer 2nd Class
    Join Date
    Mar 2004
    Location
    Monterey Calif.
    Posts
    192

    Default Re: Mercruiser - test for bad impeller?

    Diesel Walt. What's pressure testing the drive? Thanks, Been.

  5. #5
    Chief Petty Officer
    Join Date
    Aug 2003
    Location
    New Jersey
    Posts
    574

    Default Re: Mercruiser - test for bad impeller?

    Hello, Filling the drive with low pressure air (usually less than 10 psi) then you spray all the seals and suspected leak areas and see if you get bubbles. It's usually a good idea to vacuum test also (pulling a slight vacuum insted of pressurizing with air) Sometimes the vac test will reveal a leak where the pressure test will not. You can do this by taping a automotive radiator pressure testing tool into the fill plug for the outdrive lube. I use the fill tube fitting and fit it to the pressure tester. If the unit won't hold pressure or vacuum then you have a seal leak. I believe the time period for the pressure/vac test is about two minutes. If it can't hold for that long start looking at having the outdrive resealed. Hope this answered your question.
    The only thing that works on an old boat is its owner!

  6. #6
    Chief Petty Officer
    Join Date
    Aug 2003
    Location
    New Jersey
    Posts
    574

    Default Re: Mercruiser - test for bad impeller?

    I forgot to list in the last post, you spray all of the suspected leak points with soap suds from a spray bottle!
    The only thing that works on an old boat is its owner!

  7. #7

    Default Re: Mercruiser - test for bad impeller?

    took your advice and replaced the impeller last night, took me about 1.5hrs, not bad. Noticed that the last guy never put a gasket in one spot and never installed the water tube guide. So i guess it was a good idea to have done it right!thanks,

  8. #8
    Petty Officer 2nd Class
    Join Date
    Mar 2004
    Location
    Monterey Calif.
    Posts
    192

    Default Re: Mercruiser - test for bad impeller?

    Thanks Fireship. I never heard of this procedure before. I have replaced the top seal at the short shaft yoke where the u-joints are. Both that seal, a big o-ring & the u-joint yoke because the seal wears it out there where it rides. I presume there is a big seal at the bottom too, just like the one at the top that holds the oil in. How big a job is it to get to that one? Do I need any special wrenches or tools. I have the bearing retainer nut wrench that I used on the top side. It's also called a spanner wrench. Thanks in advance, anyone, BeenLurkin.

Similar Threads

  1. Alpha One Gen I Impeller Test - Does this Look Right?
    By actaeon9 in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 5
    Last Post: July 26th, 2009, 01:15 AM
  2. Test result after replacing impeller...Help...
    By basstracker2008 in forum Force & Chrysler Outboards
    Replies: 11
    Last Post: February 24th, 2008, 02:37 PM
  3. Impeller test
    By sebas54 in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 12
    Last Post: September 26th, 2007, 02:08 PM
  4. Possible to test an impeller???
    By rndcomp in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 9
    Last Post: July 1st, 2007, 07:55 PM
  5. 85 Mercruiser 170 (3.7L)- way to test impeller??
    By webnetxpress in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 3
    Last Post: April 20th, 2004, 06:46 AM
  1. iboats Forum Directory - Over 100,000 forum posts organized by topic