mystery water in bilge!

nextboat1 · May 8, 2013

Hello, I took the boat out today and noticed that water was starting to accumulate in the bilge, enough to kick on the pump a couple times in about an hour span. I first suspected the bellows, which I changed a couple weeks ago. I pulled the drive and everything was dry as a bone. While on the water I crawled in the bilge to look around and could not see a source for the leak. All the hoses look good, block plugs look good, manifolds and risers look good ect. I do not have any thru Hull fittings (transducers ect.) The boat is a 21ft cuddy with a mercruiser 5.7 and an alpha Gen 2 drive. It also has thru Hull exhaust. The y pipe is still installed and capped inside the boat. Any help would be greatly appreciated.

Don S · May 8, 2013

Re: mystery water in bilge!

If you can't find the leak, what makes you think it's an engine or drive problem?

You have to first find a leak and know where it's coming from before you have a chance of fixing it.

nextboat1 · May 8, 2013

Re: mystery water in bilge!

I agree with you Don, however, without being able to locate where the water is coming from I cannot rule any possibility out yet. Thus, I post on iboats to look for pointers and advice on where to look next.

Don S · May 8, 2013

Re: mystery water in bilge!

Put the boat in the water in a very quiet place get in there and listen. You will find it.

nextboat1 · May 8, 2013

Re: mystery water in bilge!

Thanks Don. Just out of curiosity, if it were the y pipe, which is what I think it is, would I be able to block the exhaust port (where the bellows attach) on the transom plate to stop the leak. I know that I should install a block off plate in place of the y pipe but would this work until I have the oppurtunity to pull the engine and fix it correctly?

500dollar744ti · May 9, 2013

Re: mystery water in bilge!

How could the Y-pipe be leaking water? You said it is capped off, if it's capped off, you don't need a block off plate.

Even if the exhaust bellows is completely missing, no water should be leaking in.

Why was the thru-hull exhaust installed anyway?

nextboat1 · May 9, 2013

Re: mystery water in bilge!

The exhaust bellows are not installed, and the y pipe is capped off with rubber caps and hose clamps. I thought that water might travel through the transom plate into the y pipe and leak into the boat via a faulty gasket. Just a thought. The thru Hull exhaust was installed by the previous owner, I'm unsure as to why.

fat fanny · May 9, 2013

Re: mystery water in bilge!

Is your bilge plug seaping water via the threads and or it's seal it's self?

nextboat1 · May 9, 2013

Re: mystery water in bilge!

That thought crossed my mind, however, I could hear a drip coming from somewhere.

500dollar744ti · May 9, 2013

Re: mystery water in bilge!

nextboat1 said:
The exhaust bellows are not installed, and the y pipe is capped off with rubber caps and hose clamps. I thought that water might travel through the transom plate into the y pipe and leak into the boat via a faulty gasket. Just a thought. The thru Hull exhaust was installed by the previous owner, I'm unsure as to why.

There's only one seal where the y-pipe goes to the transom plate and it does not usually fail. You said that you replaced the drive bellows but have you inspected the shift cable bellows?

I would definitely be checking the shift cable and bellows before anything else.

If the shift cable bellows is cracked, I would consider replacing the cable along with the bellows, especially if it is original. That will certainly let water dribble in at a slow rate as you describe.

nextboat1 · May 9, 2013

Re: mystery water in bilge!

Shift bellows, u joint bellows water intake hose, and the shift cable were all replaced a couple weeks ago. I will have to check the shift bellow again to be sure but I believe its OK.

As for the y pipe, rather than jumping to conclusions and pulling the engine to remove it, what I want to do is cap off the flange on the out side transom plate where the exhaust bellows would attach. This should keep the water from entering into the y pipe thus stopping the leak. If I still have a leak after that then I will know its from another source, correct?

wgl333 · May 9, 2013

Re: mystery water in bilge!

Another option is to add water to the bilge while on the trailer and inspect that entire area to see if you can find water escaping....

500dollar744ti · May 9, 2013

Re: mystery water in bilge!

nextboat1 said:
This should keep the water from entering into the y pipe thus stopping the leak. If I still have a leak after that then I will know its from another source, correct?

I'm pretty sure it will still be leaking after that. The y-pipe is designed to be half-full of water with the engine stopped.

Can you tie the bow to something strong and put it in reverse gear, then watch to see if the rate of water entering increases?

I am wondering if the previous owner installing a thru-hull exhaust has any relation to the issue you're having now.

nextboat1 · May 9, 2013

Re: mystery water in bilge!

I sure can. If the flow increases what would this indicate?

Thanks to everyone for all the help thus far.

Hoosmatroos · May 9, 2013

Re: mystery water in bilge!

wgl333 said:
Another option is to add water to the bilge while on the trailer and inspect that entire area to see if you can find water escaping....

You have to put in a lot of water to rule that out.

My suggestion, clean and dry everything and than follow Don S.'s advise

You can put some paper towels on the floor/inner transom plate to see where the leaking starts.

mystery water in bilge!

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