Home Forum Ask A Member 9.5 OMC leaking exhaust question

Viewing 6 posts - 11 through 16 (of 16 total)
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  • #14931
    johnyrude200
    Participant

      thank you for taking the time to explain this. Very helpful info for future repairs (the 9.5’s are very popular motors on the open market).

      #14938
      fleetwin
      Participant

        US Member - 2 Years

        Yes, the symptom will be a motor that runs like crud, or stalls out with the cover on, but cleans up and runs OK with the cover off. There is usually a blackish coating on the cowling insulation foam as well.
        Please don’t let test tanks fool you though. This engine is likely to suck its own exhaust when running in a tank because it sits down so low. You sure wouldn’t want to pull the engine apart needlessly.

        #15082
        johnyrude200
        Participant

          I’ve been using a fan when running motors for awhile to try and avoid the motors choking on exhaust, but more important, so I don’t inhale exhaust. So hopefully that has helped abate the issue across the board with all motors I am servicing.

          #15502
          johnyrude200
          Participant

            Well, much like jury duty, I guess my name has finally been drawn. Have my first leaky exhaust skirt for a 9.5 tonight. Runs totally fine at all ranges with the hood off. Put the hood on, and the motor dies out.

            I can see water squirting up through the rear starboard side of the skirt, so I’ll be tearing it down in the AM to replace from a parts motor. A couple of questions so I don’t have to do 5 tear down/reassembly’s chasing the source(s):

            1. I had to do a full overhaul on the gearcase for this motor and noticed there is no #6 SEAL,Impeller housing and part #7 WASHER, Seal. This is a early 9.5 model that does not have vibration dampeners. Does anyone know if earlier models lacked this seal? If this seal is missing, wouldn’t this allow the area below the exhaust skirt to fill with water and force it’s way up past the skirt, allow exhaust to enter the powerhead area?

            2. I will have to take a look at the #78 BOOT,Shift rod.

            3. Is it possible that if the #6 seal is missing, then this could essentially negate the ability of the the exhaust skirt from working due to water forcing it’s way past it? The water was basically squirting up past the skirt when I observed it. The form of the exhaust skirt seems like it was designed to basically wedge itself against the lower housing as water/pressure pushes up against it.

            4. Has anyone noticed that earlier models which lack the vibration dampeners are more prone to these exhaust leaks, due to everything just getting shaken up so much?

            I was wondering if there are any tricks folks have developed if a replacement skirt was not available? I was thinking a large glob of silicone during reassembly, and being REAL careful to make sure it stays air-tight. Silicone is flexible, is good up to 600°, and won’t deteriorate in water.

            #15506
            frankr
            Participant

              US Member

              Refer to #1. If the seal is missing it WILL cause smoke inhalation. That certainly needs replacement before going into it any further. Think about it, there is exhaust under pressure in the area around the water pump. The seal on top of the pump keeps that exhaust out of the tube that the drive shaft runs in. If exhaust does get into that tube, it goes up the tube and out the vent hole at the top, which is in the area under the hood. Cough, snort, choke, gasp.

              You just cannot evaluate these motors for an exhaust leak properly in a test tank. If you suspect an exhaust problem, take it for a boat ride.

              #15614
              johnyrude200
              Participant

                I replaced the seal from a parts motor and now everything works correctly with the hood on. The water that was blubbering up past the skirt stopped; I am guessing that the pressure of the exhaust was pushing it’s way past the skirt and allowing water to squirt up too, so thankfully I didn’t have do a full tear down to replace that skirt.

                Just goes to show what sloppy work by one person can create headaches for the next guy and a chain of other problems…find the source and we’re on our way!

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