Weed eater engine conversion

Discussion in 'DIY Marinizing' started by Ward, Jun 2, 2003.

  1. copterdoc
    Joined: Sep 2014
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    Location: NW Illinois

    copterdoc Junior Member

    I tried that right off the bat.
    The worm gear drive simply generates too much heat, and burns up the lube.


    There is a clutch. And it's not the problem.

    I was hoping that it was the problem. But it's not.

    I'm running a HUGE amount of gear reduction on this drive.
    In order for it to work at all, the design demands it.
     
  2. tom kane
    Joined: Nov 2003
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    Location: Hamilton.New Zealand.

    tom kane Senior Member

    Keep trying... James Wynne the inventor of the inboard/outboard propulsion had the same problems of heat damaging the gearboxes when developing his idea..look at it now.
     
  3. Erich_870
    Joined: Feb 2009
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    Location: Juneau, Alaska

    Erich_870 Junior Member

    Here's some guidance for the video.

    -you holding camera aimed at the gear box portion of you motor-

    "This is my gearbox, it worked great until it broke. Let's take it apart and see what happened."

    -you take it apart and show the viewers what broke-

    You're welcome :rolleyes:
     
  4. copterdoc
    Joined: Sep 2014
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    Location: NW Illinois

    copterdoc Junior Member

    I'm not ready to show those cards just yet.

    I did solve the gear box issue.

    There's a newer version out now that uses a beveled input pinion set rather than a worm gear, and it still achieves the same total gear reduction.
     
  5. copterdoc
    Joined: Sep 2014
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    Location: NW Illinois

    copterdoc Junior Member

    BTW, it wasn't A part that failed. It was the lube that failed.

    The lube failed because the worm gear drive produced too much heat.

    When the lube is destroyed by heat, it can't do it's job.

    And that doesn't cause A part to break. It causes all the parts that require lubrication within the assembly to fail.
     
  6. copterdoc
    Joined: Sep 2014
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    Location: NW Illinois

    copterdoc Junior Member

    I watched this video that you posted on youtube.



    Your gear head is NOT sealed well enough for operating while immersed. Sealed bearings will not stop water from intruding into the gear case and contaminating the lube.

    If you remove the snap ring and disassemble the gear box, you'll find milky, water saturated lube, that can't do it's job.

    If you want to keep water out of the lube, you need to use a garlock type seal on the output shaft, and you need to seal the tube at the input end so that water can't reach the input shaft.
     
  7. Yobarnacle
    Joined: Nov 2011
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    Location: Mexico, Florida

    Yobarnacle Senior Member

    Recommend the most viscous heaviest gear oil (not grease) you can find to buy.
    It will help the seals retard water intrusion.

    British Seagulls used EP 140 same as SAE 140 gear oil.
    Available from:
    saving-old-seagulls.co.uk
    and
    sheridanmarine.com

    in fact, the Seagull had no seals just bronze bushing bearings, stainless shaft, and iron gears.
    The bit of water that leaked in, created a heavy soap type emulsion when mixed with this heavy oil. The soap was the lubricant.
    Seagulls last forever just about.
    Something to consider.
    I'm still using seagull lower units 4:1 reduction, with original 50 year old bearings and gears, long after the motor heads were worn out and useless.

    (off topic but for inboards, use water pump grease in shaftlog seals, not all-purpose grease. Much heavier grease and seals/lubricates better.)
     

    Attached Files:

  8. Erich_870
    Joined: Feb 2009
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    Location: Juneau, Alaska

    Erich_870 Junior Member

    :Shrugs:

    You very well may be correct. It's worked for 3 years and hasn't given me any issues. A replacement gear head is $25 on eBay.

    Erich
     
  9. Tillerman6
    Joined: Sep 2014
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    Location: Sagle, Idaho

    Tillerman6 Junior Member

    Copterdoc,

    Just to rule out the not so obvious type of problems-- are you turning the gearbox in the direction that it was intended to run? Some gearboxes will turn with your fingers bacwards, but generate lots of heat if the gear mesh is run in the opposite direction that it was designed for.

    Also you say that the gearbox is a worm drive, and the picture does not support that idea. I could see bevel gears or even helical bevel gears like a 4 1/2" angle grinder has with that gearbox housing, but it does not look like a worm drive housing to me if that picture is related to this thread.?

    Since there was no prop on this weed whacker when it was built there is still a question of whether the bearings or bushings are installed in a normal fashion and what kind of lubrication is in use? Too much grease can cause overheating too, as it overpressurizes the gear lash up. I know this because of my 4 1/2" grinder. It is not quite the same metal to metal friction, but it does limit the RPM and the gearbox heats up abnormally hot.

    I used to think that more grease is better and just pack it full and cram the lid on, but unfortunately that is not the way to go. There has to be some air space in the gearbox for air expansion and to avoid the lube being "overworked" for lack of a better word.

    Earl White

    Earl White
     
  10. copterdoc
    Joined: Sep 2014
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    Location: NW Illinois

    copterdoc Junior Member

    Yes.

    The new gearbox (beveled input pinion) is performing very well, and now has several hours on it.

    Runs cool as a cucumber.

    I believe that you have confused the video I linked from Erich_870's youtube channel, with a picture of my gearbox.
    I have not posted a picture of my gearbox.
     
  11. Tillerman6
    Joined: Sep 2014
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    Location: Sagle, Idaho

    Tillerman6 Junior Member

    Copterdoc,

    I thought that might not be your setup. Sorry for the mixup. After I thought about it for a while I realized that an overheating "lower unit" would be hard to troubleshoot. Under water and all. Anyway, you were leaving me guessing. Glad that you have it running better now. These things can be tricky to make them work right. Still want to see some pictures if possible.
     
  12. parkland
    Joined: Jul 2012
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    Location: canada

    parkland Senior Member

    Just throwing this in the hat, thought about it the other day.

    What about a pressure washer jet drive?

    Just put the pressure washer motor and pump in the bottom of the boat, and make a tiller / nozzle at the back, to propel the boat forward.
    Maybe a thrust nozzle around the pressure jet.

    Would need some kind of filter on the intake though. Maybe a small precharge pump.
     
  13. Jim Caldwell
    Joined: Aug 2013
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    Location: Cleveland, Ohio

    Jim Caldwell Senior Member

    Not enough water volume, typically I to 2 gallons per min.
     
  14. parkland
    Joined: Jul 2012
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    Location: canada

    parkland Senior Member

    my 6.5 is 3.6 gpm @ 2900 psi.
    I imagine the psi depends on the jet installed.

    But, at that flow and pressure, I think some major thrust could be made using a nozzle around the jet.
     

  15. SCHWIMMWANNEN
    Joined: May 2013
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    Location: Poland

    SCHWIMMWANNEN Junior Member

    My conversion motorized kayak & Long Tail 3Hp





    The previous version of the engine 2.5HP







    I also edited stabilizing floats - from such a catamaran.






    And this previous project - Canoe & Long Tail & rudder








    Rudder & Long Tail
     
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