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2014 Yamaha F90 - After 20 hour service engine water flush looks like oil is leaking

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  • 2014 Yamaha F90 - After 20 hour service engine water flush looks like oil is leaking

    I'm new to boating and recently purchased a new Stringray with a Yamaha F90 engine. I brought the boat in for 20 hour service. After I noticed that when I water flush the engine it looks like there is oil residue (rainbow colored fluid) left on the ground after the flush. Is this normal? If not what could the issue be?


  • #2
    I too have a F90 - oil change on the 4 strokes can be quite messy if you do it the conventional way, and can leave some residue that will show up as a sheen afterwards.

    It also may be some thick oil residue from the lower unit oil if this oil was changed as well.

    I'd make sure your oil drain plug is torqued properly and the screws on your lower unit are torqued properly just for safe measure.

    Have you taken it in the water for a cruise after the service? If you have not I wouldn't worry unless you see droplets of oil.

    IF you start doing the oil changes yourself I would highly recommend a little gizmo called "tilt and drain" .
    Tilt N Drain Oil Drain Kit | eBay
    $15 and saves a lot of mess/cleaning.

    Enjoy that new motor!


    • #3

      When I flush my F100 sometimes also leave some little oil residue on the ground but I never worry about that because is too little. I think is normal!

      About the oil drain I use the same method inspired on this video:

      Yamaha 4-stroke oil change.wmv - YouTube

      which is exactely the same used on that oil drain kit. 1st time I've seen this kit. I had to get a m14 hose and any kind of tube/pipel


      • #4
        you dont have to be paranoid about these things as the motor is still under warranty so why worry if something goes wrong take it to the dealer ,plus thee will always be smear of oil on the skeg as the mechanics wipe the drops with a rag that leaves a smear and it shows when you put the motor in the water


        • #5

          I did take the boat out on the water after the service. I guess I'll flush when I try to winterize and see if there is still more residual oil left on the ground.

          Thanks for the great info.