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  1. #1

    Unhappy 1999 Polaris SLTH 700 - remove cylinder head while motor still in hull?

    I have a 1999 Polaris SLTH with the 'domestic' red 700 2-cyclinder motor. The motor was rebuilt in late 2014.

    It was running great until just last week. On the way back to the dock after a 1hour ride, it started running rough. It seemed like it was running on one cylinder.

    Before pulling it out of the water, I confirmed that it was only running on the front cylinder.

    I pulled it home and the next day removed the spark plug. The electrode was bent and touching the center electrode. Not good news!

    A flashlight did not reveal much on the way of damage to the piston.

    I then did a compression test: 140 on the front cylinder and 30 on the rear cylinder. Again, not good news! I am hoping it is just a ring or something similar.

    My question is: Can I pull the head etc. with the engine still in the pwc? I don't want to pull the motor or remove the exhaust manifold or intake manifold unless I have to.

    Once I pull the head, where do I go from here?

    Thanks in advance. Bill
    Last edited by K447; 09-03-2016 at 05:11 PM. Reason: Thread title, not a Fuji engine


  2. #2
    Click avatar for tech links/info K447's Avatar
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    The damaged spark plug tip suggests something has come apart inside the engine and the debris knocked around in the combustion chamber and whacked the spark plug.

    The debris either came from the piston itself or from something in the crankcase, probably a connecting rod bearing given the low compression reading. I imagine the engine sounds awful when running, probably has a major rattle or clunking sound.

    My guess is that the engine will need to come out.

    You certainly can remove a cylinder head with the engine in the hull. Remove the water manifold bar, then the cylinder head cover bolts. Remove the red head cover then remove the inner cylinder head.

    use labeled ziplock baggies for the bolts and bits as you go. Take photos, make notes.

    How many running hours on the engine? Salt or fresh water riding?

  3. #3
    ThrottleOut's Avatar
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    Based on your description of the spark plug gap being closed it's very likely that a crankshaft bearing let go and was sending chunks of metal up into the cylinder. You'll probably have to pull the motor to repair it but you could pull the head and head cover to see what you can prior to pulling the engine. Make sure you pull the PTO coupler prior to removing the engine if you have to.

    BTW, you have a Red Domestic engine and not a FUJI engine.

  4. #4

    Re: Hours etc.

    I had the motor rebuilt in Sept. 2014, both the top and bottom was done. I probably have less than 60 hours on the motor between last year and this year. I haven't even begun to think about what caused the failure, so I am open to suggestions. Was it probably caused by a lean condition? Or will I know more about the cause once it is apart? I just now noticed that I have the dreaded gray Tempo fuel lines and plan on replacing them once I get the motor done. Obviously, I want to get to what caused the failure and fix that as well. Thanks in advance.

  5. #5
    Click avatar for tech links/info K447's Avatar
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    When the engine is out of the hull and taken apart, sometimes the failure cause becomes apparent.

    Old fuel hoses, even with rebuilt carb, means the fuel system was not maintained. Other things such as fuel filter and fuel selector valve also must be replaced periodically.

  6. #6
    Looks like UND3RxOATH has hijacked my thread. I was hoping to use it for pictures etc. when I got my motor taken apart. Bill

  7. #7
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by bhumeny View Post
    Looks like UND3RxOATH has hijacked my thread. ...
    Moved

  8. #8
    Yuk! It snowed today. I guess summer if officially over. I am going to pull the motor out of my 98 SLTH and tear it apart on the bench. Quick question for those familiar with the engine removal process: Am I supposed to be able to get the motor out of the hull without first removing the exhaust manifold? I don't think I can remove the exhaust pipe unless I first remove the exhaust manifold. Seems to me, when I had the motor rebuilt and had to install it, I installed both the exhaust manifold and intake manifold on the motor when it was out of the hull. But, I wasn't able to get the exhaust pipe back into position. I then had to remove the exhaust manifold, put the exhaust pipe roughly in place and then install the exhaust manifold, working around the exhaust pipe. The engine removal procedure says: 4.5 (Below) Remove the top Exhaust bolts with a 19mm socket and wrench. Remove the pipe from the hull. But I wasn't able to do it, there was no room. Thanks in advance.

  9. #9
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    explain HOW the gap was closed guys?pull a dome and look how far that plug is away from the top of the piston.wet wolf says he's seen this before and i agree its a severe lean condition that has over heated the plug.seen many a 700 like this without a single mark on the dome.better pull those carbs ad look for a clogged jet or screen on the rear cylinder.usually this happens on the front cylinder

  10. #10
    Sooo...how much for the 780? stimpsonjcat's Avatar
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    If there isn't any damage to the head or the piston top, then nothing got loose. Unless the piston got loose and got shoved up against the plug and left there (broken wrist area or broken arm)

    when things get loose in there the damage is generally VERY obvious.

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