Results 1 to 7 of 7

Thread: outboard jet impeller/sleeve problem

  1. #1
    Member
    Join Date
    Apr 2006
    Location
    Fairbanks
    Posts
    327

    Default outboard jet impeller/sleeve problem

    I just installed a new liner and impeller in my outboard. 40hp Johnson, late 80's. After adjusting I only have 3 shims left for future adjustment. I had to put 6 shims behind the impeller to get good clearance between impeller/liner. I'm thinking something isn't right. All the old parts matched the new parts. Any ideas as to what is going on?

    Thanks

  2. #2
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    A new sleeve and impeller usually requires 4 or 5 shims for me. I have extra shims so I use 10 or 12 total if I need them. You may want to check your shaft end play. Make sure your bearing isn't getting loose. Nothing good happens when your jet shaft bearing fails. It never happens in the driveway. On the other hand, I've shimmed my jet to where it was snug in the driveway but wouldn't even turn to start in the silty Big Su.

  3. #3
    Moderator AKmud's Avatar
    Join Date
    Oct 2005
    Location
    Wasilla, Alaska, United States
    Posts
    3,185

    Default

    Is your impeller stainless or alum? If it is alum, it may be worn as well. You might try comparing it to a new one to see if there is much of a diameter difference. They do wear out as well.
    AKmud
    http://i78.photobucket.com/albums/j96/AKmud/213700RMK1-1.jpg


    The porcupine is a peacful animal yet God still thought it necessary to give him quills....

  4. #4
    Member
    Join Date
    Nov 2006
    Location
    Alaska
    Posts
    48

    Default

    Is your sleeve (liner) seated? I'd check that. If yours has the two screws on the sides, you'd know it was right when the screws threaded in. If it's properly seated, have you compared your new impeller to your old one? Are the dimensions the same? Is this the first time you've installed new impeller and sleeve? If not, how many extra washers did you have last time? If so, I'd tighten it up and go run it. I wouldn't get as hung up on how many washers you have as I would about the clearance between the impeller and the sleeve.

  5. #5
    Member
    Join Date
    Apr 2006
    Location
    Anchorage
    Posts
    3,293

    Default

    If the sleeve wasn't seated it would require fewer shims. If this sleeve is the old type with the lateral bolts make sure you run the bolts in and out a few times to relax the thread cutting tension. The new style jets don't need the lateral anti-spin bolts.

  6. #6
    Moderator AKmud's Avatar
    Join Date
    Oct 2005
    Location
    Wasilla, Alaska, United States
    Posts
    3,185

    Default

    I was always told by the jet guys that there should only be 7 shims (in some combination top/bottom), if it can't be properly shimmed with them then something is out of whack. You might give Gary a call at Greatland Welding, he does a lot of jet unit stuff (sales too) or J. Kimberly in Anchorage (by far the outboard specialist shop in Anchorage).

    If your impeller diameter gets too small you may run in to an over-rev situation with the engine. It would be like putting too small of a prop on your lower unit. Find out what the wide open throttle max for your motor should be and compare it with where you are currently at. If you are revving too high it is time to change the impeller.
    AKmud
    http://i78.photobucket.com/albums/j96/AKmud/213700RMK1-1.jpg


    The porcupine is a peacful animal yet God still thought it necessary to give him quills....

  7. #7
    Member
    Join Date
    Apr 2006
    Location
    Fairbanks
    Posts
    327

    Default

    The impeller I installed was virtually new. I fit both a new impeller and this impeller in the new sleeve and both fit identically. My old impeller sat a lot deeper in the new sleeve. My old liner was worn out, enough to where the impeller was hitting the sleeve locating bolts. I have the old style sleeve, not shouldered.

    I have 9 shims total. 6 are behind the impeller, with 3 left for future adjustment. I could always put a few more in, just a matter of having enough thread.

    It seems like with new sleeve and new impeller you should only need to use a shim or two, not six!

    I talked with The Boat Shop and they have seen this a few times. They talked to Outboard Jets and this was within their machining tolerances at the time. They said some of them are the other way around, and they need to shim the foot down because with zero shims the clearance is too tight.

    Thanks for the ideas guys.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •