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HELP NEEDED ASAP Honda 115 low compression and can't find out why!!!!

FishinjeffFishinjeff Posts: 56 Deckhand
in Boating #1
I took the head off and had it cleaned and shaved. Could not find a crack in the head or the block and piston. Put it back together and I still have low compression on cly 3. It has to have a crack or a valve issue, but I looked it over pretty good and had 2 others look at the head. Can there be a crack I cant see??? I know about the "issues" with this motor. It is one of the original models. So what else can I do to narrow my compression leak down?
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Replies

  • gmiller0737gmiller0737 Posts: 664 Officer
    #2
    A Cylinder Leak Down Test should help You find The Problem.https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test
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  • larrywittlarrywitt Posts: 2,895 Moderator
    #3
    gmiller0737 wrote: »
    A Cylinder Leak Down Test should help You find The Problem.https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test
    Great info.
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  • FishinjeffFishinjeff Posts: 56 Deckhand
    #4
    Ok. It seems harder to do on an outboard due to no water sealed in the head if its a cracked head issue. Since I know there in low compression I think I can just do TDC and compress air to the cyl. and just listen. I can't believe when I had the head off I could not find any visual problems.
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  • gandrfabgandrfab Posts: 21,646 AG
    #5
    Friend of mine had a honda 115 3 or 5 years out of warranty lose compression in one cylinder.
    Honda covered the power head but not the labor to change the power heads out.
    Call honda tell them what happened but I would leave out that you took it apart.
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  • FishinjeffFishinjeff Posts: 56 Deckhand
    #6
    They did replace the other motors block about 12 years ago. The motor is now almost 16 years old with maybe 750 hours on it. I doubt Honda will step up to the plate on this one, even though it is the model with the known head cooling issues.
    So step 2 today I did the leak down test on #3 and I can hear it/air coming out on the exhaust side OR through the cooling passages? Compression was 50 psi. I went ahead and took the head off. Getting easier to do now:willynilly
    I checked the block again and the head and I seem to have the exhaust valves not closing enough. All tension off the rocker arms and I can see a difference in the other valves. So off to the machine shop for further review.
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  • FishinjeffFishinjeff Posts: 56 Deckhand
    #7
    UPDATE, So it seems the valve seats are corroded from behind pushing up and not letting the valve seat right. Basically Honda's known issue has finally come to light 15 years later. New head time!
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  • gandrfabgandrfab Posts: 21,646 AG
    #8
    Fishinjeff wrote: »
    UPDATE, So it seems the valve seats are corroded from behind pushing up and not letting the valve seat right. Basically Honda's known issue has finally come to light 15 years later. New head time!

    I don't want to take the job on, but I was lapping valve seats in my teens for car motors.
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  • Alex from GAAlex from GA Posts: 1,691 Captain
    #9
    Do you mean the seat is coming out of the head? If this is so you can install new seats for a less than a new head. Any automotive machine shop can do this.
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  • FishinjeffFishinjeff Posts: 56 Deckhand
    #10
    The real problem is a design flaw that has caused corrosion from the water jacket through the back of the valves. So the heads metal has pushed the valve seats "up" and no longer holds compression. $1100 for new head + another head gasket 135. I really think I need to bite the bullet on a new slightly better designed head.
    B-reak
    O-ut
    A-nother
    T-housand
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  • gandrfabgandrfab Posts: 21,646 AG
    #11
    Well at least you don't have to replace the whole power head.
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  • Soda PopinskiSoda Popinski GrovelandPosts: 16,495 AG
    #12
    Fishinjeff wrote: »
    The real problem is a design flaw that has caused corrosion from the water jacket through the back of the valves. So the heads metal has pushed the valve seats "up" and no longer holds compression. $1100 for new head + another head gasket 135. I really think I need to bite the bullet on a new slightly better designed head.
    B-reak
    O-ut
    A-nother
    T-housand

    Unless you own once you don't truly understand how accurate this statement is.
    You can't pet a dead dog back to life 
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  • gandrfabgandrfab Posts: 21,646 AG
    #13
    Soda Popinski wrote: »
    Unless you own once you don't truly understand how accurate this statement is.

    Have had 4 boats before I learned to pick up rides. Now i'm down to 3 boats in different stages of disrepair.
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  • Soda PopinskiSoda Popinski GrovelandPosts: 16,495 AG
    #14
    gandrfab wrote: »
    Have had 4 boats before I learned to pick up rides. Now i'm down to 3 boats in different stages of disrepair.

    I've just had the one for a little over a year now. Love it but man it's money money money
    You can't pet a dead dog back to life 
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  • FishinjeffFishinjeff Posts: 56 Deckhand
    #15
    Even though I am disappointed in Honda over this known design flaw, the twin 115 has been pretty good to me for going on 16 years. I had issues with trim seals on both motors, a primary ignition magnet cracked, the starters got so corroded I just replaced them, and thats about it. Oh the main power cable turned into shredded wheat looking copper. It is all the rest of the boat that has been sucking down my money, lol.
    As much as I rinse the boat after use corrosion is extreme on the boat and motors. :banghead
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  • FishinjeffFishinjeff Posts: 56 Deckhand
    #16
    If you want to save as much money on a boat as possible learn how to be a electrician, plumber, carpenter, and mechanic. Maybe even an upholsterer, welder, and a fiberglass guy?
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  • gandrfabgandrfab Posts: 21,646 AG
    #17
    Fishinjeff wrote: »
    If you want to save as much money on a boat as possible learn how to be a electrician, plumber, carpenter, and mechanic. Maybe even an upholsterer, welder, and a fiberglass guy?

    <--- is in the industry and we had a meeting it is no longer break out another thousand.
    It's now break out another thirteen hundred.
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  • FishinjeffFishinjeff Posts: 56 Deckhand
    #18
    I was thinking the same thing after I wrote that. Head and gasket will be 1300. Although I already spent 330 on other stuff. Last year was 2300.
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