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  1. #1

    97 780 SLT exhaust manifold leak concern

    Just dropped a good used engine in my SLT. I used the old exhaust manifold gaskets. I worked on it and after priming it a bit, it fired off and would run smoothly. I premixed because I want to check the oiler system so it is getting probably double the oil needed. Smokes a ton but runs smooth.

    After I made sure it would run, I put it on the garden hose and noticed I have a leak on the MAG cylinder out by the right hand side bolt. I always start the engine first, turn on the water and then shut off the water and kill the engine.

    I removed the manifolds last night and noticed white/brown oil sludge in the manifold and muffler. The gasket was damaged right by that bolt so it appears water was leaking in and out of the manifold. I checked the spark plugs and they are a nice wet coat of oil on them but no sludge. The piston in the exhaust port was oil coated and no sludge.

    If water was leaking into the exhaust of the MAG cylinder, could it have gotten into the engine/crankcase? Should I just install the new gasket I bought and not worry about it?


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Sounds like it will be fine.

    The exhaust flow should have blown the leaking water down the exhaust, so the engine remained dry inside.

    Shutting the water off first, as is always recommended, means the residual water should have been well downstream by the time the engine stopped running.

    Spray some fogging oil into that cylinder and carb intake (and crank it a few turns) if it is going to sit for a few days before you get it running again

  3. #3
    Where did all that sludge come from? I did put a shot glass of oil down each cylinder before I started cranking on it to get the gas to pump up into the carbs. I don't know if that generated that much sludge though.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by WaveChaser View Post
    ...I did put a shot glass of oil down each cylinder before I started cranking on it to get the gas to pump up into the carbs...
    Say what?

    You put an ounce of oil into each cylinder? Through the spark plug hole?

    Did you then put the spark plugs back in and cranked it?

    If you put enough oil in, you risked hydraulically locking the piston. Liquid doesn't compress, so there is the risk of cracking the piston or bending a connecting rod.

    Oil inside the cylinders would have no effect on carb priming anyways. If you wanted to prime the fuel lines and carbs, just seal your hand over carb each intake to create a suction inside the carb.

  5. #5
    I wasn't doing that to help prime it. I did that to protect the cylinder from no oil because the complete fuel system was dry and I had to crank on it awhile. I ended up pouring some gas down each carb anyway to get it started. It wasn't a regular shot glass it was the plastic disposible ones.

    It seems to be running fine. Very smooth and quiet with nice throttle response.

    The torque on the manifold bolts are 25ft-lbs and the large bolds are like 45 ft-lbs?

  6. #6
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    reused exahust gaskets?

    With all due repsects....WHAT were you thinking?, the only excuse could be it was a great day, you didn't have replacements on hand and you figure you neede the practic doing this job twice. Of course it's going to leak, unless you have the luck I never had.

    One thing I learned early on is that most used gasket packages have a label on them that says in very fine print (2x the labor and half the fun.).

    Of course, replacethe gaskets and be generous with the copper gasket spray, clean all surfaces, blah, blah, blah.

    For new engine startups I always squirt some 20-1 premix into the intake manifolds and hold the oil pump cable full on for a few moments.

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