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2000 90hp Engine Blown?!

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  • 2000 90hp Engine Blown?!

    I have a 2000 90hp 2-stroke that overheated and will not start again. Compression is just below 70 in all 3 cylinders. Does this mean the engine is blown?

    Background info that may be helpful: I was having an overheating alarm issue when going over 4000 rpms (the engine appeared to be peeing just fine with lots of water pressure). It had been about 2 years since the water pump was changed so I changed that along with the thermostat, pressure relief valve and temperature sensor. The alarm still went off when over 4000 rpms. I then pulled the exhaust and cylinder covers and found blockage and salt water corrosion inside the water ports. After cleaning thoroughly, replacing the gaskets, and running it, the alarm did not go off and it was running great during the 30 minute test run on the lake. I stopped about every 5-7 minutes and could put my hand on the sides of the engine (cowling off) and it was not hot at all. The pee water was the same temp as the lake water. Then running back to boat ramp it overheated, lost power and will not crank again. The engine was incredibly hot. Being cash-strapped, I am trying to decide my next move. Any and all help is greatly appreciated.

  • #2
    OK, what do you mean by won't "crank"? do you mean it wont turn over with the starter? can you move the flywheel by hand? how did you test the compression if it wont turn over (crank)

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    • #3
      In my opinion if you shut it down when alarm came in it should not have damaged it from over heating , just like the other times.

      Unless you did something different this time

      Could be your compression gauge is not reading correctly.

      Is it getting spark?

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      • #4
        It is getting spark and the compression gauge is brand new. It cranks fine but just won't turn over. The last time it overheated there was no alarm so I never knew it was getting hot.

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        • #5
          There you go again, cranks fine but wont turn over!! what is cranking if it isn't turning over? if the motor is indeed "turning over/cranking" by the starter, and the compression is quite even, you may be OK, what did the plugs look like when you pulled them out? is the primer bulb pumping up nice and firm? can you confirm there is fuel in the tank? can you confirm that fuel is getting to he carbs by removing a drain screw from the float bowl? get a small torch and have a look through a spark plug hole and see what the pistons tops look like.

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          • #6
            I thought turning over meant starting - it cranks but will not START. The flywheel turns fine. Fuel bulb is firm. Plugs looked ok to me but were dry. I am running from a portable tank that is full and has always worked good. Will take a look at piston tops tomorrow.

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            • #7
              there is cranking over and turning over, but then there is the firing up or starting up and they are different things

              dry means no fuel to me

              Seems you did not hook up the over temp system after replacing things

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