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Flapper Exhaust Valve

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  • Flapper Exhaust Valve

    Hey guys,
    During the instalation of Exhaust Manifold and Risers on Volvo Penta 5.0 Gi 1999 I found the Flapper Exhaust Valve in this position.
    Is there any testing or maintenance to know if the valve is operational?
    Thank You
    Flapper

  • #2
    Use your finger to see if it moves easily and drops back to that position, which is normal.

    Is the sealing rubber intact? Can't tell in the pic. When you close it, the exhaust should be pretty much closed by the rubber.
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    • #3
      Is this an original installation and also a VP drive ?

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      • #4
        Those were used up to about '99 or so, then Volvo put out a TSB that they should be removed, because they could melt from an overheat and block the exhaust, and they felt that they were not effective in keeping water from coming up the exhaust. They were a hold over from OMC where Volvo used OMC's transom mount design during the joint venture and used many OMC design parts. I have the same ones on my engine, and have not had problems with them, except I did have to replace them due to an overheat once. Personally I did not agree with Volvo on this point, because I never had water come up the exhaust on this boat. I feel that some kind of flapper is needed on sterndrives, if not this design (which is very similar to Mercruisers who still use this type of flapper) them maybe a larger flapper like that used on inboards, in place of the exhaust bellows. I have seen a few Volvos set up this way, an inboard style flapper installed on the exhaust opening of the gimble housing.
        1988 Four Winns 200 Horizon
        4.3 OMC Cobra

        98 Jeep Grand Cherokee 4.0 Selectrac
        07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

        "While air doesn't freeze....rust never sleeps"

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        • #5
          Pretty sure my ‘89 VP didn’t have flappers. The drive did have a rubber flap on the exhaust though.

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          • #6
            totally different design. The '89 is the Swedish AQ design, the '99 is the adapted OMC Cobra design. They used a lot of OMC parts during this time period:
            thermostat housing
            bell housing
            inner and outer transom mounts
            exhaust system
            only real differences from the original OMC Cobra was the cone clutch shifting in the upper gear housing and some minor changes to the pivot housing.
            I still think they were wrong about the flappers!
            1988 Four Winns 200 Horizon
            4.3 OMC Cobra

            98 Jeep Grand Cherokee 4.0 Selectrac
            07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

            "While air doesn't freeze....rust never sleeps"

            Comment


            • #7
              Yes, the sealing rubber is intact.
              The drive is original VP SX-M 1,60. The engine 5.0 GI from 1999.
              Thank You

              Comment


              • #8
                I had those flappers on my 1995 Four Winns 190 Horizon with a 5.0Fi (302 Ford w/fuel inj) There is a 3/16" stainless rod that the flapper pivots on. The rod is supported by rubber bushings in the aluminum exhaust pipe. At about 300 hours since new, I had bushings fail and a flapper came loose. It went downstream in the exhaust system and lodged in the transom area, which restricted the exhaust to the point that the boat struggled to get on plane, lost 600-700 rpm and about 15 mph at top end. My flappers were rubber coated aluminum. I have to think that if an engine overheat caused the flapper to melt, the exhaust "Y" pipe would also be melting and rubber hose connections burning. Think about beaching a boat and having a wave or the wake from another passing boat by hit your transom. The flappers do hang partially open at rest. A surge of water coming up the exhaust system toward the engine would close the valve at least temporarily, but a submerged transom would still cause water in the engine. As mentioned, Volvo did publish a service bulletin somewhere around 2000 to remove the flapper valves.

                Comment


                • #9
                  Actually that's not what happens at least not in my case. I had a bad overheat and the flapper valves were the only thing damaged, the exhaust Y pipe is aluminum and the rubber hoses on mine were still intact. I replaced the flapper valves and the grommets that retain the steel pin and that was it. If the retaining grommets came loose, one cause I can think of is that the hoses that connect the Y pipe to the 90* pipe that connects to the exhaust elbow were not long enough. These hoses are supposed to be long enough to cover the part of the Y pipe with the steel pins and grommets so they can't move out of position.
                  One of the flappers was melted in place (grommets and pin still there) the other was in the bottom of the exhaust housing and I had to remove the drive to get it all out.
                  Replaced the flappers & grommets and its been fine for years thereafter.
                  If I removed these flappers, I'd want some kind of flapper valve like those used on inboards on the opening of the gimble housing, to keep water from rushing up the exhaust pipes.
                  1988 Four Winns 200 Horizon
                  4.3 OMC Cobra

                  98 Jeep Grand Cherokee 4.0 Selectrac
                  07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                  "While air doesn't freeze....rust never sleeps"

                  Comment


                  • #10
                    Wow, that flapper looks.....impressive!!! On mine, the rubber bushings either were damaged during installation or were compromised somehow. There was no indication on the outside of the Y pipe and hose. The pins wore the bushing holes in the aluminum Y pipe and eventually fell out. The Volvo "fix" at the time was to use a special order $100 drill fixture tool to drill new bushing holes in the Y pipe, glue the rubber bushings in the y pipe with an adhesive like 1357 or 1100, and re-assemble. With the boat on the trailer I was able to disconnect the exhaust bellows from the transom shield and see the flapper. I was able to attach a long wire to the flapper and pull the flapper back up and out. I also found a shaft when I removed the anode on the bottom of the transom shield.

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                    • #11
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                      The other one was totally vaporized, at the bottom of the exhaust housing. Despite the overheat the engine ran normally and no water in the oil for 2 more seasons. Then blew the head gaskets at the end of the third season following the overheat. Likely due to the overheat 3 years before. I wound up rebuilding the top end with reman heads, and converted from the OMC one piece exhaust system to the two piece system used on later OMCs and Volvos. I installed reman heads because the old heads had cracks in the exhaust valve seat area (prob from the overheat) and the cooling passages were eroded from 15+ years of raw water cooling in salt water. Still running fine 2 years after the rebuild.
                      1988 Four Winns 200 Horizon
                      4.3 OMC Cobra

                      98 Jeep Grand Cherokee 4.0 Selectrac
                      07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                      "While air doesn't freeze....rust never sleeps"

                      Comment

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