2008 150 hp Yamaha

Discussion in 'Outboards' started by Sanpan, Jul 26, 2013.

  1. Sanpan
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    Sanpan New Member

    I have a 2008 150 HP Yamaha 4 stroke out Board that has overheated as a result of the impeller malfunctioning. The head and block have a slight warp. They will need to be planed 10000th of an inch each. Does anyone know if this can be done with success, I thank you in advance for your input.
     
  2. CDK
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    CDK retired engineer

    As both head and block are similar light alloys that are held close together by a lot of very strong bolts, there is little need for correction of such a small warp.

    How did you measure the 10000th inch ? Are you sure about the number of zeros?
     
  3. Sanpan
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    Sanpan New Member

    2008 Yamaha 150hp

    I had it into a Yamaha dealership and they measured the warp after taking the power head apart. I have compression in one cylinder only 120, 05, 08 and 06 so three are very low compression.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Always good to get a second opinion, I don't understand how things got to the stage of major damage without alarms sounding, or the motor shutting itself down, or restricting rpm.
     
  5. DCockey
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    DCockey Senior Member

    My guess is the shop said "ten-thousandths" and it was interpreted as 1/10000 but what the shop meant was 10/1000 or 0.010.

    Did the shop offer an opinion on the probability of success?
     
    Last edited: Jul 28, 2013
  6. CDK
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    CDK retired engineer

    Probably, yes, but the decimal point must be shifted right: 0.01 inch or roughly a quarter of a millimeter.

    The compression test figures mean there is virtually no compression on 3 cylinders. In my experience that tells me there is much more damage than just a warped head, so the proper course of action should be a complete overhaul including -but not limited to- correcting the head/block mating surface.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    The lack of compression is possibly attributable to destroyed rings, if it got hot enough to warp the head and the block. It is a re-build job by the sounds of it.
     
  8. Sanpan
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    Sanpan New Member

    Thanks everyone for your input. The shop has said that if they shave the block that the pistons could hit the top of the head and they are not aware of a gasket kit that will be thicker than the OEM. They also said that it would change the compression if the shave the head and block and I would have to run premium gas. I have spoken to a few shops and some say it can be done and others say it can not. This is far to expensive of a motor to scrap or should I salvage the parts and sell them on E-bay, the motor only had 46 hours when it blew?
     
  9. jagans
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    jagans Junior Member

    I am not an expert in the Yamaha line of outboards, but Something stinks about what this shop is spouting. No compression means you may have holes burned through your pistons. I would take your motor to an old reputable shop and have them pull the heads and see what you have. I would pull the plugs and boroscope the cylinders. .010" should not cause interference IMHO, nor that much increase in compression if you mill. Heck, you could make that up with an additional head gasket if that's possible.
     

  10. Toooshy
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    Toooshy New Member

    I guess this is all old news but if the damage was warp heads the shop should of show you a blow head gasket. Most likely the heads warp after removel which happens a lot. making a thicker head gasket is no big deal, but as CDK stated there more to this. Just so happens I'm looking for a outboard what this Yamaha worth?
     
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