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Smoke with Yanmar 4JH2 DTE Engine

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  • #31064

    I have a Yanmar 4JH2DTE engine in my Nauticat 331.

    The engine develops expecially after starting a lot of smoke.

    It is not blue smoke, rather grey.

    I assume that the combustion is not good.

    What I already did:
    Check the compression (is ok about 30 bars)
    Changed one injection valve

    The engine ist not using oil. Oil level is ok. No biodiesel fuel used. Fuel from several stations is used.

    Has anybody made the same experiences? Any advice? Or is this normal with this type of engines


    I found we had a bit of smoke after a number of years out of the water. I assumed that it was a little water in the fuel. Let it run for a while and it cleared up.

    victor crowhurst

    It could be head gasket leaking, it would get worse when the engine is at normal temp under slight load when water is at highest pressure in the cooling system and fuel/air mix is just becoming rich. Check the compressions in each cylinder, wet and dry and also if you can check how long the pressure stays when the piston is at TDC for each cylinder. This may tell which part of the gasket is leaking. It could also be incorrect shotting in the fuel pump, difficult to diagnose and fix, needs a pump engineer with the correct bench test machines- could be expensive.

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