dna

Within the last few days I have noticed that my engine sounds louder when firing it up and cruising. I have captain choice exhaust and normally leave it 'closed', where the exhaust goes out the leg. I just realized that one side is going up the top exhaust while the other is going down the leg. I tried to switch the exhaust back and forth many times, but no change. In each attempt the solenoid is turning the valve/switch on top of each y-pipe. It seems like the flapper inside the one side is either broken, or just not closing all the way.

Any advice on how to fix? Are the flappers typically replaceable, or will I need a new y-pipe?


Thanks

Tinkerer

Is this the air operated Mercruser type. If it is remove the air line and put a drop of dish soap in and reconnect the air line. If they are electric solenoids and they are both working then you may have a broken flapper. My SCARAB used to spit them out at least one a year.

dna

Motor is a 454 Merc, but not sure if the captain exhaust is factory or aftermarket. Either way it is electronic solenoid. Both are working, just that one side is not 'closing' even though the solenoid is switching the flapper. Sounds like a flapper is gone - are these replacable, or do I need a new diverter?

Thanks

Tinkerer

They usually just bolt onto the shaft. I always kept a spare with extra bolts.

dna

Anyone have recommendations on how to remove the y pipe diverter. I loosened all the clamps around the rubber exhaust joiners, but it doesn't budge. Is it best to keep working it, or is it best to remove the riser. My concern is that I see lots of rust where the riser bolts attach to the manifold - I concerned that the bolts are rusted and may snap.

Any suggestions?

Thanks

Tinkerer

The rubber glues itself to the pipes. Take a long skinny screwdriver and slide it between the rubber and the pipe and work your way around the pipe. They will come loose. I could change my flappers by reaching up the tail pipe. Did you try that?

dna

Well, I wiggled, wiggled, wiggled! Eventually got the diverter out. The flapper was totally gone, along with the 2 bolts. Took it to the local merc shop and they confirmed it is the stock merc cast iron diverter. But looking at the PC he could not find this exact one - mine has a vertical shaft, where most Merc diverters are horizontal shaft. Anyway, he gave me a surplus flapper he had, which was oval shaped and bigger in all diameters. Spend about 1.5 hrs on the flapper with my grinder, and eventually made a perfect fit. Put it all back together and works perfect. Oh, I put locktite on the new bolts - hopefully that will prevent it from happening again soon. A job I was expecting to take an hour or so ending up taking the whole day (like usual I guess)

BTW - I think in the future I will try to install the flapper from the back exhaust pipe. I didn't do it this time cause I needed the diverter off to take to shop to hopefully find the proper flapper. Though I made a 2nd custom flapper too, so next time it is being installed from the pipe.

Thanks

Tinkerer

The problem is that locktight doesn't work well because the heat from the exhaust burns it up. Sometimes You can stake the back side of the bolts where they extend through the shaft.

Griff

You are not supposed run the diverters closed above I think 3000rpms. It may be even less than that.

dna

Really? I never heard of that - what is the issue if I do keep them closed at 4200+ rpm? I generally keep them closed all the time since we live on a small lake and when open the boat can be heard from all the house along the lake. I think there are also some laws that if I keep them open I may have some issues with the local cops.

Hopefully the only issue keeping them closed is the flappers eventually falling off - I can always replace them.

Thanks