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Yamaha f115 head gasket blew-need to replace cylinder head?

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  • Yamaha f115 head gasket blew-need to replace cylinder head?

    I have 2000 Yamaha 115 four stroke, was out Saturday and had loss of power/missing issues. The diagnosis this morning was a blown head gasket.

    A couple questions:

    1) We think (this is a new to me boat) this may have been caused by the exhaust port being submerged when launching and idling at the dock (we are divers, this is on a 18 foot Avon RIB, it was loaded heavy in the stern). Could this be the cause? I think the take-away here is loading the boat differently and launching it with the motor trimmed up a bit.

    2) The mechanic is mentioning cylinder head replacement as well. Uggghhhh. How often is this needed when you blow a head gasket, and (go ahead, slap me when I'm down) what is the ballpark cost?

    -Doug

  • #2
    Re: Yamaha f115 head gasket blew-need to replace cylinder head?

    A blown head gasket is not typically a reason to replace a cylinder head. If water injestion is the cause you could have bent some valves and even that would not be reason to replace the head. New valves would take care of that issue. Are you saying the engine is running when you launch? If so, there is no cooling when the engine is out of the water so an overheat condition may have caused the blown gasket. Overheating can also crack a cylinder head and in that case, yes, it is necessary to replace it. Head gaskets can blow for no apparent reason so replacement of the gasket is all that's necessary. It all boils down to what actually happened. Are you telling us the whole story? As for cost -- well lets just say you aren't going to like it and since Christmas is coming, consider it a very expensive Christmas Gift to yourself.

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    • #3
      Re: Yamaha f115 head gasket blew-need to replace cylinder head?

      Thanks for the reply-I promise I'll give all the info I can.

      No, the engine isn't running out of the water. I launch with the motor off, get it in the water, and am usually able to push it off the trailer. It is a pretty light boat.

      But, in water, at the dock, it had the exhaust port submerged, basically blowing bubbles when idling. I was wondering if the submerged exhaust ports equaled water getting into the exhaust manifold-maybe the backpressure there blew the head gasket. But, pure speculation on my part.

      I don't think it overheated, there weren't any alarms, and it seemed to be running fine, just rough. No real production of white smoke or anything like that either. That being said, this is a new motor for me, so I'm still getting familiar with it.

      There was water in the oil, and also a bit of oil/water mixture around the air intake.

      -Doug

      [EDIT] Just got a message from the tech, he's saying a complete powerhead replacement, but I don't know the basis for this.

      Comment


      • #4
        Re: Yamaha f115 head gasket blew-need to replace cylinder head?

        Okay, one tech is saying new powerhead and new cylinder heads.

        The thing is still running, however.

        I got a second opinion, and am taking it to that shop-they think it could be a few things, none of which involve replacing the powerhead.

        Comment


        • #5
          Re: Yamaha f115 head gasket blew-need to replace cylinder head?

          when you at the techs shop look for a minimum of 4 stroke certified,advanced 4 stroke would be better and a master tech certificate from yamaha wont hurt.
          yes I have seen the odd head gasket fail just cause.
          rare but it happens.
          before I replaced the block I would assemble it,after having the head checked at a competent machine shop,leave the cams out and perform a leakdown test.
          would be nice to do a leakdown test prior to engine dissasemply to check cylinder sealing condition.
          if after head gasket replacement the leakdown test looks good finnish the assmbly and run it.
          job isnt hard for the average backyard guy as long as the service manual is followed closely.
          clean all the valve shims and carefully mark them with a magic marker for correct reassembly or you will find its a time consuming process to reshimm all the valve lash clearences.
          always use new headbolts on final reassembly as they are an angle torque fastener.
          no tech questions by PM, they wont get answered.
          you have to be trusted by the people that you lie to .

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          • #6
            Re: Yamaha f115 head gasket blew-need to replace cylinder head?

            Thanks rodbolt and Silvertip.

            Turns out what was happening was water intruding through the upper exhaust port-the boat was a bit loaded down in the back (and, even though this boat is rated for a four stroke 115, RIBs in general haven't adapted to the extra weight of a four stroke). We had loaded it on the trailer, and then I dropped it in with the motor down, I'm guessing that procedure led to the motor getting fairly far down in the water while it was off.

            I took it to a different shop and the tech flushed the motor, he said he did 4-5 oil changes on it over the course of yesterday. No blown gaskets, no structural damage, the oil was actually still fairly viscous. The plugs were a bit fouled and the oil filter was obviously shot, so he replaced those and adjusted the ECM. It is running like a champ now.

            I'll be shifting weight forward in the boat, and will be mindful of not submerging that exhaust port, the boat will go in with the motor up, and I'll keep it slightly trimmed up while idling around.

            At the end of the day, it was a full day's work and a tune up on the motor. $700 in total costs, which is the easiest $700 I've ever spent.

            I've also found a great shop, Jacobsen's Marine here in Seattle (actually out in Ballard). They were great to deal with.

            -Doug

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            • #7
              Re: Yamaha f115 head gasket blew-need to replace cylinder head?

              which goes back to what I said, a leakdown test will not only show the cylinders ability to sael but if it cant seal then it shows what is leaking.
              there is no ECM adjustments on that motor, the TPS voltage is about the only adjustment possible.
              glad your problem was a simple one but always have a cylinder leak down test run when testing a 4 stroke.
              no tech questions by PM, they wont get answered.
              you have to be trusted by the people that you lie to .

              Comment


              • #8
                Re: Yamaha f115 head gasket blew-need to replace cylinder head?

                Yeah, my bad-not ECM, just a tune up. I was relaying what I got over the phone.

                Compression was fine, the mechanic was able to see what had happened in terms of water intrusion from the exhaust, so I don't think he did a leakdown.

                I'll get it out soon for a test run.

                Comment


                • #9
                  Re: Yamaha f115 head gasket blew-need to replace cylinder head?

                  a compression test on a 4 stroke outboard is a teat on a boar hog.
                  have a leak down test done.
                  its faster and vastly more accurate than a compression test.
                  no tech questions by PM, they wont get answered.
                  you have to be trusted by the people that you lie to .

                  Comment


                  • #10
                    Re: Yamaha f115 head gasket blew-need to replace cylinder head?

                    An unfortunate update:

                    Leak down it will be.

                    Took it out last week, ran it for ~2 hours at 4100-5000 rpm. It ran like a champ.

                    Today, I checked the oil, it came gushing up out of the dipstick.

                    White/grey in color, slight gasoline smell to it.

                    We all assumed it was water from the upper exhaust port being submerged, but now I'm not so sure. Maybe thermostat sticking?

                    This isn't fun, that's for sure.

                    Comment


                    • #11
                      Re: Yamaha f115 head gasket blew-need to replace cylinder head?

                      when you do the leakdown test make sure you you carefully listen for air in the crankcase.
                      if that motor cannot turn 5700 RPM with its normal load it will make oil.
                      also carefully check the VST vent for a VST float needle leak and the fuel pump diphram for leaks.
                      the fuel pump can be tested with a standard pressure vacum tester without dissasembling the pump.
                      the odds of injesting water via the bottom cylinder while running due to engine weight is someplace between slim and none.
                      quit hunting that field.
                      no tech questions by PM, they wont get answered.
                      you have to be trusted by the people that you lie to .

                      Comment


                      • #12
                        Re: Yamaha f115 head gasket blew-need to replace cylinder head?

                        Leakdown test results:

                        Cylinders 1, 2, and 4 are all less than 5%

                        Cylinder 3 is at 30%.

                        The tech hears some hissing through the oil dipstick hole. He's going to get on the phone with Yamaha and talk with them a bit.

                        Comment


                        • #13
                          Re: Yamaha f115 head gasket blew-need to replace cylinder head?

                          and yamaha is going to tell them,like I am, to do a thorough decarb job preferably with the YDIC injector set up.
                          then retsest.
                          if the numbers come up you may be ok,if not its possible to have gasses leaking past the headgasket,along with cooling water, into the crankcase.
                          no tech questions by PM, they wont get answered.
                          you have to be trusted by the people that you lie to .

                          Comment


                          • #14
                            Re: Yamaha f115 head gasket blew-need to replace cylinder head?

                            There was a massive amount of water, relatively speaking, in the oil.

                            1.5 hours of operation equaled overflowing oil from the dip tube.

                            Yamaha thought it was corrosion in the oil pan for some reason, or an outside chance of a blown head gasket.

                            We're pulling the heads off now.

                            Comment


                            • #15
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                              Re: Yamaha f115 head gasket blew-need to replace cylinder head?

                              sometimes being the Easter Bunny just aint no fun.
                              it will help if you and your tech will sit down and figgure out a hunt plan.
                              first,was water entering a cylinder? spark plugs will show distinctive marks and colors for water burn,especially salt water.
                              the reason I say the submerged idle relief cannot allow that kind of water when running is simple.
                              you will bend a rod due to hydrolock first.
                              now, where can we leak water in and not oil out?
                              any corroded spot in the cooling system that enters a non pressurized spot in the crankcase/oil sump area including any failed gaskets.
                              any spot on the head surface with oil drain backs near a cooling water passage.
                              30% leakage isnt good but I dont think your going to see a piston ring or valve problem.
                              thats why I would decarb BEFORE pulling the head and recheck #3.
                              easter egg hunting can cover a lot of territory,the object is to narrow the hunting grounds.
                              I personnally dont like easter egging a problem but occasionally its simply part of the job.
                              the trick is to carefully analyze all the information about the hunting ground,eliminate the areas you can first then go hunting with an educated plan.
                              wont be the first time I have had to make plates and such to use air pressure to pressurize blocks,heads,adapters and such.
                              occasionally you simply have to understand how it works and create a plan to elimintae sub assemblies one by one.
                              no tech questions by PM, they wont get answered.
                              you have to be trusted by the people that you lie to .

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