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  1. #1
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    Finding out why my gt-150 blew

    Before I get rid of it, I wanna see if I can fix my gt-150. It has zero compression in cylinder 3. What would be the first step in seeing if the problem is something smaller like a ring?

  2. Ohio Fishing Reports Moderator omcforever's Avatar
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    #2
    Like was said in the threads you posted before. Pop the heads and transfer port covers (on all cylinders) and take a look. Will give you an idea. You still need to check cylinders for gouges, grooves, wear, over bore and taper and see if they are in spec and can be bored/honed, whatever.

    http://www.bbcboards.net/showthread....9836&highlight=
    Last edited by omcforever; 01-21-2018 at 06:31 PM.

    Age and treachery will always overcome youth and skill !!

  3. Ohio Fishing Reports Moderator omcforever's Avatar
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    #3
    Even if it just needs say a ring set and hone on one cylinder, motor still has to come off and be completely dis-assembled down to the bad cylinder at least with all new gaskets. I would rebuild carbs also just to be safe.

    Age and treachery will always overcome youth and skill !!

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    #4
    Is the diagnosis part a long or hard process?

  5. Ohio Fishing Reports Moderator omcforever's Avatar
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    #5
    Nope,,pop the heads and transfer port covers and take a look. Look for broke rings, ring damage, cylinder damage, excessive carbon buildup on piston skirts and ring area, signs of no fuel, metal pieces, burnt pistons, ect. That will give you an idea what needs attention. Use an inside micrometer and dial indicator to check taper and runout and bore diameter. The factory repair manual tells you how to do these things. I have a factory manual for that motor if you need one.

    Age and treachery will always overcome youth and skill !!

  6. Ohio Fishing Reports Moderator omcforever's Avatar
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    #6
    Pop the head on the bank of the bad cylinder and also the transfer port cover and take some pics and post em up...transfer port is the pear shaped cover on the outside of the cylinder block of each cylinder. Yours is under the wiring junction strip on the starboard side of the motor/middle cylinder(#3). Should have 6 1/4-20 bolts hold each one on/some have 4. You can then look at the side of the piston and rings and ports. Use a pick and press on the rings to see if they are broke or froze. We will concentrate on the bad cylinder first. ***dis-connect battery before doing this***
    Last edited by omcforever; 01-21-2018 at 06:53 PM.

    Age and treachery will always overcome youth and skill !!

  7. Member
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    #7
    Thank you! Is this diagnostic a long and hard process? I've done carbs before and can change lower unit oil, plugs, etc without even blinking an eye.

  8. Ohio Fishing Reports Moderator omcforever's Avatar
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    #8
    Read post 6 again....takes maybe an hour or so. if your going to tackle it, buy an OMC manual.
    Last edited by omcforever; 01-22-2018 at 08:22 AM.

    Age and treachery will always overcome youth and skill !!

  9. SC Club Moderator ChampioNman's Avatar
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    #9
    Once you have that head off you'll pretty much know. Post up pictures and we'll give it a look.

  10. Member
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    #10
    I've got a seloc manual in front of me and I'm looking at the powerhead section. The explanation of popping the head isn't too clear. Is this a good manual?

  11. SC Club Moderator ChampioNman's Avatar
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    #11
    It's better than a Clymer's best bet would be to download a manual from the link posted in the stickies at the top of the page. May cost you a few bucks but worth while. It's not that hard to remove the cylinder head just follow the bolts that go around the head. Don't remove the ones on the head cover, the head bolts are flange style bolts.