Water Leak at Exhaust Flapper

texsun · Sep 27, 2004

My 96 Larson 3.0 VolvoPenta is spraying water from a hole that is at the back of the plastic exhaust tube. The tube that leads from the riser to the bottom of the transom. From drawings I have seen I believe this is the hole where one side of the "flapper" mounts/fits. At first I thought it was a hole in the bellows, but by using a mirror this wkend I can clearly see it's on the plastic tube. What causes this leak/spray and how can I repair it? Thanks for the Help! Mark

Don S · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

If by the plastic tube, you mean item 56, it's made of aluminum. The bellows (item 31) is rubber and should cover the holes for the shutter. The bellows (31) may also be bad and in need of replacement.

crazy charlie · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

Remove and inspect the rubber exhaust tube.As Don stated the bottom of the rubber tube should cover the small hole for the flapper hinge pin.If the flapper is worn or the pin is gone then replace it.Most exhaust tubes have 2 clamps on each side so make sure there are 2.Charlie

texsun · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

Thanks Don & Charlie, Don you are exactly right on the diagram. My thought, after looking at it carefully is that the bellows was never pulled down properly from the factory. Should I simply loosen both hose clamps and slide the bellows down to cover the hole? That would mean sliding downward about half an inch. I read what Charlie said and I'm wondering whether the flapper is working properly. One Volvo parts person indicated that Volvo said the flapper was not a critical part and may be removed completely. What do ya'll think?

crazy charlie · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

You can do a search on that topic and get many opinions.The flapper/shutter is designed to stop water from entering the exhaust and going against the proper exhaust flow and in turn getting water in the motor and catastrophe.Many motors are positioned high enough where it is unlikley to happen even without shutters.Just as many motors if not more are at the height that make them vulnerable in a following sea or if loaded with passengers and a rapid deceleration occurs.I say if a motor comes with it then it belongs in there.For $30 a pair I dont want to take any chances.It is one of the easiest replacements and cheapest you will ever do.Charlie

MrBill · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

Careful if your boat is in the water. With enough weight toward the stern, removing the exhaust part can allow water to enter the boat if the water level is higher than the pipe top. It is on mine if I'm in the rear of the boat.

crazy charlie · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

MrBill,make sure you dont take the advice of others here that recommend running without flappers.Charlie

texsun · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

Thanks for the advice. I agree. When I inspect & repair/replace the flapper...should I pull the bellows down enough to cover the flapper fittings completely? I really appreciate the Help! Mark

crazy charlie · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

Absolutely!!The pin should take up enough space that it may seep a drop or two but not more than that.Charlie

butlp · Sep 27, 2004

Re: Water Leak at Exhaust Flapper

Texsun, If I were you, order a replacement flapper (comes with new bushings) and a new bellows. The flapper has probably long gone and the bellows is now 8 years old and either hard or starting to crack. I found on my 1997 4.3 that a couple of the hose clamps had been over tightened and were junk, so for the small additional cost order 4 new clamps too. As MrBill said, don't try this in the water!

texsun · Oct 2, 2004

Re: Water Leak at Exhaust Flapper

OK I removed the riser and bellows today. The flapper and the pin were still there but both the bushings (items 54 above)were gone. The holes in the exhaust pipe had been elongated downward about 1/4 of an inch, I suppose by the force of the Exhaust/Water flow. The Volvo parts store that I spoke with said that Volvo nolonger sales the flapper and has stopped using them on newer models. I made the decesion to go without the flapper (after looking at those mangled holes, The bushings/pins would not fit properly anyway) 1) What's the best way to fill/cover holes? Charlie's advice was well taken..but I just don't know if I should use only the bellows to cover the holes.2)Do you think those bushing will "pass" thru the exhaust without further damage? Thanks for Your Help! Mark

rodbolt · Oct 2, 2004

Re: Water Leak at Exhaust Flapper

hello we have welded many of the elongated holes. we also found that the flappers in that exhaust were a waste of time and effort. make sure your riser height is at or above volvo's recommended height. volvo did away with them in 95 on the sx drive. I would weld them then use an aircraft length drill bit to redrill the holes usually slightly higher than the originals. good luck and keep posting

texsun · Oct 3, 2004

Re: Water Leak at Exhaust Flapper

Thanks Rodbolt, 1)Can that welding operation be done while the exhaust pipe is on the boat or does it have to be removed? 2)What about JB Weld for this repair? 3)The drill bit would only be required if I intended to replace the flapper..right? I really appreciate the Help! Mark

rybad · Oct 5, 2004

Re: Water Leak at Exhaust Flapper

JB Weld will work fine. I used it on my Riser, which is subject to much more than the tube. I woulc make sure you don't really need the flappers first. If you riser is not high enough, you'll risk water backflow into your cylinder. There are plenty of aftermarket resources on the internet that sell the flappers. They run about $40-$50 a pair, and come with the bushings. (try ebasicpower.com) -David

texsun · Oct 6, 2004

Re: Water Leak at Exhaust Flapper

Where can I find the Spec or Bulletin to see whether or not my riser meets the minimum/ recommended hieght requirements? Thanks Again, Mark

texsun · Oct 13, 2004

Re: Water Leak at Exhaust Flapper

Hey Rodbolt, Thanks for your advise about welding. Did you weld these holes while the pipe was still on the boat? I spoke with one welding shop and they will not do the job unless the part is removed. The dealer basically says R&I the engine to remove the part. I know welding is the "right" repair but the JB weld is starting to look real good. Can it be done while still on the boat? Thanks Again, Mark P.S. Dealer said the minimum hieght from top of riser to the water line is "about 22 inches" to run without the flapper.

texsun · Oct 22, 2004

Re: Water Leak at Exhaust Flapper

Received call from Volvo tech today and he faxed me a Volvo Service Bulletin that advises removing the exhaust flapper because in their words the flapper was ineffective at preventing water ingestion. Also noted that because of the flappers short lifespan it has been known to disconnect and clog the exhaust system. It goes on to give instructions to remove the entire assembly including pin,flapper and bushings - fill the holes with silcone and go around the pipe with masking tape to cover holes. Draw the exhaust bellows down past the holes and tighten securely. Hopefully this will be useful information. Mark

rodbolt · Oct 22, 2004

Re: Water Leak at Exhaust Flapper

that goes with what I have found in 30 years. most flappers are useless. if you have a problem odds are the tops of your risers are to close to the waterline. good luck and keep posting

Water Leak at Exhaust Flapper

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