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  1. #1
    Join Date
    Jun 2015
    Location
    Assens, Denmark
    Posts
    152

    Default 1GM10 Black sludge not moving boat.

    Hi.
    I am new here.
    I have been on the Honda outboard forum for a number of years, but am now the proud owner of a sail boat and in need of assistance.

    A bit of background.
    I am a Kiwi living in Denmark, where I live its only a 5 minute bike ride to the marina and the Baltic. I have owned motor boats for a number of years but have finally taken the plunge and brought myself a 31 foot sail boat. She is Boström B-31 an old girl from the mid 80s.
    I brought her only at the end of the season (a couple of months ago).
    She has a newly renovated 1GM10 motor in her that starts well and looks to be in good shape.
    But i feel the motor is not coming up in revs while in gear there is water coming out of the exhaust and also a lot of black soot/sludge. The motor is so useless that she will not push my boat at all, the tiniest bit of cross or head wind and i am blown onto the pilings.
    I hauled her up for the winter 2 days ago with a friend who is a experienced sailor. He has never come across a boat that has so little motor power we literally hopped from pile to pile to move her into place. his assessment was that she is not coming up higher enough in revs i don't have a tach on the panel so its hard to tell but i suspect he is right.

    Here's what I do know.
    The motor has been newly renovated, I was informed everything was done from top to bottom.
    The gear lever works in reverse to normal ie i move the lever back to go fwd and vice versa. i was told when i brought her that its is because the old motor gear shifter worked in reverse to this one & to change it to normal needed an expensive adaptor plate or something so the previous owner decided it wasn't really a problem. This makes me think that maybe the prop has the wrong rotation But that besides shouldn't make the biggest problem as the fwd and reverse gearing are (i think) the same.
    When i lifted her out the prop had huge amounts og growth that will of course not help the problem.
    Thats all I really know, she is now out of the water so testing is not really an option but all other work/ checks can now be done.

    All help will be gladly appreciated,
    I'm hoping my problem is something small and inexpensive.

    Many thanks.
    Dean.

  2. #2
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    3,932

    Default Re: 1GM10 Black sludge not moving boat.

    a Yanmar 9 horsepower heres a manual link https://www.manualslib.com/manual/79...mar-1gm10.html

  3. #3
    Join Date
    Jun 2015
    Location
    Assens, Denmark
    Posts
    152

    Default Re: 1GM10 Black sludge not moving boat.

    Thanks Doc.
    I have both the service manual as well as the 460 odd page workshop manual.
    I'm not short of documents, just advice on where to start.
    Thanks anyway mate.

  4. #4
    Join Date
    Jun 2008
    Location
    Posts
    564

    Default Re: 1GM10 Black sludge not moving boat.

    A 'huge amount of growth' will quite possibly explain everything. Even a small amount of growth on your prop can cause a massive difference. With such a low hp engine it can be catastrophic to performance. Growth on your hull will also cause problems but when on your prop the effect is magnified by many times. The overloaded engine will black smoke etc so that is consistent with what you saw. You also won't reach high rpms with a dirty prop. The water coming out the exhaust is probably your normal cooling water and you need to see that. Bottom line is that I would clean the hull and antifoul it, then clean and 'PropSpeed' (good Kiwi product) the prop, shaft, strut, and maybe even the rudder. Good chance that is all that you need to do. From a Kiwi sitting on his boat in Auckland getting ready to go slay some Snapper.

  5. #5
    Join Date
    Jun 2015
    Location
    Assens, Denmark
    Posts
    152

    Default Re: 1GM10 Black sludge not moving boat.

    Cheers Ali.
    I really hope your right mate but I do suspect there is more to my problem. More or less. I just don’t know.
    Good luck on the snapper I’m jellous as mate.

    cheers
    Deano.

  6. #6
    Join Date
    Jun 2008
    Location
    Posts
    564

    Default Re: 1GM10 Black sludge not moving boat.

    Fresh fillets for dinner last night. Always masses of Snapper and Kingi's available at this time of year in Auckland. Bad prop growth really can makes things as bad as you experienced so fingers crossed that is all it is.

  7. #7
    Join Date
    Jun 2015
    Location
    Assens, Denmark
    Posts
    152

    Default Re: 1GM10 Black sludge not moving boat.

    Update.
    I have had the exhaust manifold off. There is no build up what so ever. I have also noticed that the throttle linkage was set somewhat wrong and was, I don’t think receiving full travel. I have adjusted it only at the motor end and seem to get maybe a 1/4 more travel. We will see what this results in. Overall I suspect there are a few small incorrect things that once added up have a big result.
    I cant be sure until her bum is wet again. But I have a good feeling.
    cheers so far for the help and support.
    Dean.

  8. #8
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    4,335

    Default Re: 1GM10 Black sludge not moving boat.

    When it is running in gear do you get a slow drip of water from the stuffing box? You may need to pull the boat and repack the stuffing box it should drip water when the shaft is spinning. That is only a 10 hp engine it wouldn’t take much to keep it from reaching proper rpm in relation to throttle opening. That will also cause it to load up wiyh unburnt fuel.
    Last edited by kimcrwbr1; 11-22-2017 at 01:30 PM.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  9. #9
    Join Date
    Jun 2015
    Location
    Assens, Denmark
    Posts
    152

    Default Re: 1GM10 Black sludge not moving boat.

    No mate. I havnt checked the stuffing box, but she is up on a cradle for the winter now. The shaft spins freely out of gear if that’s what your referring too.
    Is there something you think I should look at?

  10. #10
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    4,335

    Default Re: 1GM10 Black sludge not moving boat.

    Just dotting the I’s servicing the shaft and stuffing box is part of preventive maintenance can only be done on blocks. If you don’t know how old the packing is replace it. Proper adjustment is when it drips 2-3 times per minute as the shaft is spinning an no drips when static.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  11. #11
    Join Date
    Jun 2015
    Location
    Assens, Denmark
    Posts
    152

    Default Re: 1GM10 Black sludge not moving boat.

    Ok
    I didn’t know that. Is there a online procedure or something I can read/ watch before I dive in?
    Thanks for the heads up.

    Dean.

  12. #12
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    4,335

    Default Re: 1GM10 Black sludge not moving boat.

    Don Casey at BoatUS for one on a quick search.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  13. #13
    Join Date
    Jun 2015
    Location
    Assens, Denmark
    Posts
    152

    Default Re: 1GM10 Black sludge not moving boat.

    I will check it out.
    Thanks.

    Dean

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