Hole in Exhaust Y-pipe

[dvan1901]

My buddy has a '94 Mercruiser, 5.0L with an Alpha drive. On Saturday he took on a lot of water and on Sunday we did some trouble shooting and noticed a crack/hole in the top of his exhaust Y-pipe. So, I have a couple questions.
1) What would cause this type of hole?
2) How much pressure is being generated in this part of the exhaust system?
2b) Could this be repaired/patched or does it have to be completely replaced?

 

[seaphase]

Re: Hole in Exhaust Y-pipe

Corrosion usually causes the holes that form in the y-pipe and it usually is a result of not flushing the engine with freshwater after running it. Most of the time you see these holes form near where the y-pipe bolts up to the transom assembly. However, that doesn't look like where this hole is. It appears to be up the y-pipe a bit. The engine will have to be removed in order to replace it. Personally, I wouldn't try to patch it.

 

[wire2]

Re: Hole in Exhaust Y-pipe

The pressure is whatever it takes to push the exhaust down into the water, probably ~1 psi. But that's enough to bring lots of cooling water into the boat thru a hole.

A patch will be very temporary, there's probably several more places that are almost corroded through, and will show soon.

If you do run in salt water, consider coating the inside of a new Y pipe with either 2 part epoxy paint or GE Glyptal. That will keep the salt off the aluminum for quite a while.

 

[Haut Medoc]

Re: Hole in Exhaust Y-pipe

I agree^^^^^^^
You could probably drill it, tap it & plug it as a temporary fix to get you through the season.....
That said, if there is one hole leaking, there are others waiting to poke through......
Best to replace it as soon as possible..........

 

[dvan1901]

Re: Hole in Exhaust Y-pipe

My thought on it was a failure due to corrosion as well; this is a fresh water boat only, but knowing that part is cast iron it can/will still rust. I think we may try to get a patch on it first...knowing we are prolonging the inevitable, but just trying to avoid having to have him pay to pull the engine and all that...they have a tight budget right now.

 

[Mark Jones]

Re: Hole in Exhaust Y-pipe

Had the same issue on my 1989 4.3LX. Always trailered and fresh water only, but developed a hole in the lower collector portion of my y-pipe. Turns out I had a "cooked flapper" that fell into the chamber and over a period of time the rattle beat a hole thru it.

Found a local boat bone yard that had several of these lying on a scrap pile and picked out one that was almost brand new for $20 that had new flappers in it! Boy, did I luck out.

 

[zbnutcase]

Re: Hole in Exhaust Y-pipe

My thought on it was a failure due to corrosion as well; this is a fresh water boat only, but knowing that part is cast iron it can/will still rust. I think we may try to get a patch on it first...knowing we are prolonging the inevitable, but just trying to avoid having to have him pay to pull the engine and all that...they have a tight budget right now.

It is NOT iron, it is cast aluminum, and will corrode even in certain freshwater types

 

[Mike_Maranto]

Re: Hole in Exhaust Y-pipe

The Y-Pipe has flaps, it may be a possiblity you have damaged flaps that some how contributed to problem.
I had the same issue like the hole in Y-Pipe, my flaps were good. I tried JB weld and other epoxies but they only lasted few hours. The right way to do is to take the engine out and replace the Y Pipe.

 

[mmajor97]

Re: Hole in Exhaust Y-pipe

You may be able to get by with a stainless repair clamp like we use on high pressure water lines where I work. Its a stainless band that wraps around the pipe and has a rubber gasket inside of it. Pretty easy if it will work. Just thinkin out loud. Just call the city that you pay your water bill to and they should be able to give you some info on where to get one from in your local area.

 

[wire2]

Re: Hole in Exhaust Y-pipe

You may be able to get by with a stainless repair clamp like we use on high pressure water lines where I work. Its a stainless band that wraps around the pipe and has a rubber gasket inside of it. Pretty easy if it will work. Just thinkin out loud. Just call the city that you pay your water bill to and they should be able to give you some info on where to get one from in your local area.

Good idea. Should work, as long as the hole is on a straight section.
Any industrial plumbing supply house will have those.

 

[dvan1901]

Re: Hole in Exhaust Y-pipe

mmajor97; good idea, but it is not on the straight part really. It is where the two "arms" come together, just before it bolts to the transom assembly.

Cast aluminum...ok, that makes sense based on the fact that I didn't see any rust on it.