Gapple12

Mercury 6.2 Exhaust flapper valve

7 posts in this topic

Just purchased a 2006 chaparral 246 with a mercury 6.2. Upon the test drive while we were headed out of cove I opened engine hatch and heard a slight tick noise from one riser area. Didn’t sound like a knock or exhaust leak. One of the guys with us said that was a Exhaust flapper valve and mercury motors always have issues with these. He said it’s a very easy fix. I looked at a riser diagram and I don’t see this part. Can anyone point me in the right direction for a parts guide on this motor ?

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15 hours ago, Gapple12 said:

Just purchased a 2006 chaparral 246 with a mercury 6.2. Upon the test drive while we were headed out of cove I opened engine hatch and heard a slight tick noise from one riser area. Didn’t sound like a knock or exhaust leak. One of the guys with us said that was a Exhaust flapper valve and mercury motors always have issues with these. He said it’s a very easy fix. I looked at a riser diagram and I don’t see this part. Can anyone point me in the right direction for a parts guide on this motor ?

MerCruiser used several different versions of exhaust system for their small-block V8 engines from the early 2000's and newer models. Best bet is to get the engine serial # to verify getting the correct version and parts. It is fair to say that Mercury had an issue with exhaust leaks from the gasket for the manifold to head (item # 5 in the picture below) not being centered correctly and thus burning out after 100 hours of running time or so. In such a scenario, a person running their hand along this area can feel the exhaust gases, as well and hear and smell the exhaust leak typically.

13270.GIF

http://www.marinepartsplus.com/catalog/mercruiser/serial/350_MAG_MPI_HORIZON_ALPHA-BRAVO/884717002/11681-200

 

If however you can hear a 'ting-ting-ting' sound at idle that sounds like metal on metal, than it is likely you're hearing the exhaust flapper(s) hitting the exhaust elbow internally as the rubber coating has worn away from wear/use, or from an overheat that has stripped away the protective rubber seal material. (item # 7 in the picture below)

 

1488.GIF

http://www.marinepartsplus.com/catalog/mercruiser/serial/350_MAG_MPI_HORIZON_ALPHA-BRAVO/884717002/11681-340

 

Purpose of exhaust flappers is to reduce the chance of water getting into the engines cylinders when coming off plane quickly, hard reverse, or a following sea, etc.

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6 hours ago, Shepherd1 said:

MerCruiser used several different versions of exhaust system for their small-block V8 engines from the early 2000's and newer models. Best bet is to get the engine serial # to verify getting the correct version and parts. It is fair to say that Mercury had an issue with exhaust leaks from the gasket for the manifold to head (item # 5 in the picture below) not being centered correctly and thus burning out after 100 hours of running time or so. In such a scenario, a person running their hand along this area can feel the exhaust gases, as well and hear and smell the exhaust leak typically.

13270.GIF

http://www.marinepartsplus.com/catalog/mercruiser/serial/350_MAG_MPI_HORIZON_ALPHA-BRAVO/884717002/11681-200

 

If however you can hear a 'ting-ting-ting' sound at idle that sounds like metal on metal, than it is likely you're hearing the exhaust flapper(s) hitting the exhaust elbow internally as the rubber coating has worn away from wear/use, or from an overheat that has stripped away the protective rubber seal material. (item # 7 in the picture below)

 

1488.GIF

http://www.marinepartsplus.com/catalog/mercruiser/serial/350_MAG_MPI_HORIZON_ALPHA-BRAVO/884717002/11681-340

 

Purpose of exhaust flappers is to reduce the chance of water getting into the engines cylinders when coming off plane quickly, hard reverse, or a following sea, etc.

Wow, thanks, can’t ask for a better reply then that.  Now I need to determine what is causing the noise and where. It sounds like something loose, not a steady sound like gasket leak. I’ll use my mechanic stethoscope and try to nail it down. 

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I’m just curious, but my boat has the silent choice exhaust. Since the stock exhaust flapper is after the silent choice, technically the noise should stop when I flip the switch and the exhaust goes out the side instead of rear ? 

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On 2/14/2018 at 8:31 PM, Gapple12 said:

I’m just curious, but my boat has the silent choice exhaust. Since the stock exhaust flapper is after the silent choice, technically the noise should stop when I flip the switch and the exhaust goes out the side instead of rear ? 

Even with a stethoscope, I don't know if I could hear a bad exhaust flapper with Quick and Quiet turned on resulting in the majority of the exhaust gas to exit out the sides vs. through the prop(s). Eyesight is good, hearing not so much. NOTE: even with Quick and Quiet turned off, some exhaust gas and noise escapes out the side exits along with through the prop(s).

I have seen the Corsa Quick and Quiet exhaust flappers make some rattling noise, often as a result of a past engine or exhaust overheat. If an overheat was bad enough, the Corsa exhaust flappers/pivot seals will often drip water into the engine compartment.

For the stock exhaust flappers after an engine overheat, the rubber material gets burned off the stainless steel plates, and the flappers often fall apart and attempt to go out through the exhaust Y pipe, exhaust bellows and prop(s). Usually in such a scenario, for Alpha drive equipped models the broken exhaust flappers will get stuck on the shift fork.

broken exhaust flappers.jpg

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Shepherd1

Thank you for that info on a jammed Alpha with a cooked Corsa.  I am felling really good now. Was about to put a Corsa on the replacement 5.0L 186. I love a 1 minute blast every time out. I would panic if they jammed the shift fork .   MOMMA  MOMMA 

I come in faster than most people.   SUPRISE old 1 eye.   :o

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