Mercruiser 260 Y exhaust pipe

[JoeRJGR]

So in trying to determine why I am taking on water, one suggestion was the Y pipe. While I could not recreate this by running on muffs, a marine mechanic told me it is possible that it is still the Y pipe based on how high the water is in the manifold....does this make sense? The boat took on water for 20 minutes after being shut off, if it was coming from the manifold wouldn't stop eventually? Also I read that a gurgling sound when taking on water is evidence of a bad Y pipe.

What I don't understand is if it is the Y pipe how could the water come through the transom or does it just look like it's coming from the transom? Does anyone have a diagram of where the Y pipe sits? I can't find any....thanks for your help!

 

[Rick Stephens]

Y pipe is connected dead center at bottom of transom and is flooded except when motor is running and then it is half water and half exhaust.

 

[achris]

 

[JoeRJGR]

Got it...makes sense now..do when the motor is not running I assume that water can come in through the exhaust bellows and into the boat.

When water was coming in, it looked to be in the area of the top screws shown in the picture. There was a gurgling noise as well...sound could have been the mixture of water and exhaust....

When running on muffs no water comes in, but if there is an exhaust leak there shouldn't I hear it when running on muffs?

Thanks achris...could not find a diagram anywhere...

 

[Scott Danforth]

no, many times people do not maintain their boat, so when the flappers burn up from lack of water flow and an over-heat, the flapper shaft drops into the y-pipe and wears on the aluminum a bit, then water corrodes the aluminum a bit.....this repeats until you have holes in the y-pipe

or, someone replaces the aluminum bottom bolts with stainless, there is then galvanic corrosion and the y-pipe corrodes and you have holes in the y-pipe.

most likely if you are not getting water in the boat when running on the muffs, simply drop the boat in the water and look. my guess is the water is coming in from near the y-pipe.

the two most likely culprits are a leaking bellows or a soft transom (rot) with water leaking past the seal because the transom deformed

 

[achris]

...or, someone replaces the aluminum bottom bolts with stainless, there is then galvanic corrosion and the y-pipe corrodes and you have holes in the y-pipe....

Those screws in my Y-pipe are stainless steel, as supplied with the engine for that job, by Mercury....

Chris......

 

[JoeRJGR]

Thanks guys, I am still unclear how water is leaking out of the top of the Y pipe (where the screws are that mount it to the gimbal housing) while the boat is not running but in the water.. Thanks again...learning a lot here.

 

[achris]

The Y-pipe seals to the gimbal housing with an O ring. If the O ring is damaged, water will leak in. Also, as already explained, the early style shutters can break their pivot pins, drop down and lodge in the bottom of the Y-pipe. It'll sit there, vibrating away and wearing a hole through the pipe....

Chris......

 

[JoeRJGR]

Chris, I always hear the flappers, so hopefully they are good...Im going to look closer at the Y pipe. I have room in front of the engine...is it possible to slide the engine forward to replace the Y pipe? Can replace I replace the o ring without engine removal? Thanks

 

[Scott Danforth]

no. Engine needs to come out

the effort required to pull the drive and unbolt/disconnect the motor to move it forward is the same effort you need to pull the motor, plus then move it forward and set it back down. why not simply keep it on the hoist and get it out of your way to allow you room to work as well as the physical room needed to remove the y-pipe.

 

[tank1949]

Those screws in my Y-pipe are stainless steel, as supplied with the engine for that job, by Mercury....

Chris......

And replacing or tightening them in a boat with motor in is almost impossible. I even added a small amount of 5200 to help make sure that they never vibrated loose.

 

[tank1949]

So in trying to determine why I am taking on water, one suggestion was the Y pipe. While I could not recreate this by running on muffs, a marine mechanic told me it is possible that it is still the Y pipe based on how high the water is in the manifold....does this make sense? The boat took on water for 20 minutes after being shut off, if it was coming from the manifold wouldn't stop eventually? Also I read that a gurgling sound when taking on water is evidence of a bad Y pipe.

What I don't understand is if it is the Y pipe how could the water come through the transom or does it just look like it's coming from the transom? Does anyone have a diagram of where the Y pipe sits? I can't find any....thanks for your help!

Raise OD and remove exhaust bellows and look inside hole. You may require a mirror. If material is clogging and causing gurgling, you may be able to use long needle-nose plyers to grab and remove. Use drill to bust it up. Harbor Freight makes a long tool (really long) I used for fish hook removal but it can also be used to remove hard rubber from semi-disintegrated shutter material.

 

[76SeaRay]

I don't think my previous attempt to post went through... If you have a harbor freight close by, they have a relatively inexpensive video inspection camera..