Leak around the transom

Jamz3333

Seaman
Joined
Oct 12, 2010
Messages
72
I have a leak coming in around the bottom of the transom it just trickles in. I replaced the drive bellow last year and the shift cable looked good. I may have not got the drive bellow sealed correctly, but if it was the drive bellow wouldnt it leak in around the drive shaft? It comes in at the bottom of the transom plate. Any suggestions?
 

Fishermark

Vice Admiral
Joined
Oct 19, 2003
Messages
5,617
Re: Leak around the transom

Is this a Mercruiser? The bad news? Chances are good your transom is rotten and leaking. :(

Could also be the lower bolts - which are an aluminum alloy - are corroded out and leaking. But if they are, then your transom itself is probably shot too.

It could also be the exhaust pipe - where it connects with the transom plate.... but either way, the engine has to come out to fix.
 

proshadetree

Lieutenant Commander
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Jul 19, 2008
Messages
1,887
Re: Leak around the transom

Thats what happened to my baylinner. When I pulled her apart rotten at the lower section. I hape its you exhaust gasket or a lose bolt.
 

Bondo

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Apr 17, 2002
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70,465
Re: Leak around the transom

Ayuh,... 9 times outa 10, it's a Rotten transom....
 

Jamz3333

Seaman
Joined
Oct 12, 2010
Messages
72
Re: Leak around the transom

Yes it is a mercruiser, is there anyway to tell if the transom is rotten or if the exhaust pipe is bad with out taking the motor out? I just dont want to put alot of money in it but if its something some what easy to fix I would do it.
 

fishrdan

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Jan 25, 2008
Messages
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Re: Leak around the transom

Take a mirror and poke it around by the suspect area where it's leaking and see if you can find it,,, while the boat is in the water. If a mirror is too hard to see that far down, try poking a digital camera down there and snap a bunch of pics.

As for the leak, I don't think you have an easy fix there... bellows, transom seal/rotted transom, exhaust seal. None of these are easy fixes. About the only "easy fix" would be if the tilt-trim hose manifold is leaking, but that would be on the bottom of my list of suspect areas.
 

proshadetree

Lieutenant Commander
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1,887
Re: Leak around the transom

I put mine nose up and filled the bilge with water. Did not come even close to the drive shaft. It leaked on the outside at lower transom. Took it apart and it was rotten.
 

Jamz3333

Seaman
Joined
Oct 12, 2010
Messages
72
Re: Leak around the transom

It very well could be the transom because this fall when i noticed it leaking it was trickling in between the inner plate and the transom. I figured if it was the drive bellow leaking then it would come in around the drive shaft. Just the joys of owning a boat...lol:facepalm:
 

Brentathon

Petty Officer 1st Class
Joined
Dec 29, 2009
Messages
385
Re: Leak around the transom

I had a very small trickle leak that I was barely able to see....it leaked from the very bottom of the transom plate.......YET, it is simply the Upper Swivel Shaft seal that's leaking, as it's wet in the area where the steering lever goes through the transom....the water just happens to run down (I don't know exactly how), and appears to leak from transom plate.
 

scubapro69

Cadet
Joined
Jun 19, 2010
Messages
8
Re: Leak around the transom

I have a 1990 17' sunbird and i had the same probem when i bought the boat. I took to several shops and they said the transom was great. Thank god. I went ahead and opted to seal around the drive with a sealer called Thermo Plastic by a company called Nuflex instead of pulling the motor and drive. Has worked excellent for over a year.
 

Don S

Honorary Moderator Emeritus
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Aug 31, 2004
Messages
62,321
Re: Leak around the transom

I went ahead and opted to seal around the drive with a sealer called Thermo Plastic by a company called Nuflex instead of pulling the motor and drive.

That is a bandaid stuck on a bullet wound. Fixes nothing, but may of stopped the bleeding for a short time.
The only way to fix the problem is to pull the transom shield and put in a new seal.
It's also very possible the exhaust Y has corroded through where the seal ring goes, or a tab has corroded and broken off. Either way the engine has to come out to actually locate the problem.
I have pulled many engines, put the drive back on. Plugged the exhaust Y, strapped the boat to the trailer and backed them down in the water and crawled into the engine compartment where the engine was and actually looked for and found the leaks.
 

Jamz3333

Seaman
Joined
Oct 12, 2010
Messages
72
Re: Leak around the transom

Ok I have got some good things to look at as soon as the weather gets a little better. More than likely I can rule out the drive boot and the shift cable boot leaking right?
 

proshadetree

Lieutenant Commander
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Jul 19, 2008
Messages
1,887
Re: Leak around the transom

Raise front of boat. Water the bilge, and look in the back. Dont go over the lower access of the drive shaft. I have found several leaks this way. and I dont have to haul to lake.
 

StevNimrod

Petty Officer 1st Class
Joined
Dec 13, 2008
Messages
343
Re: Leak around the transom

I had a very small trickle leak that I was barely able to see....it leaked from the very bottom of the transom plate.......YET, it is simply the Upper Swivel Shaft seal that's leaking, as it's wet in the area where the steering lever goes through the transom....the water just happens to run down (I don't know exactly how), and appears to leak from transom plate.

+1. This was my leak. Well, one of my leaks.
 

Jamz3333

Seaman
Joined
Oct 12, 2010
Messages
72
Re: Leak around the transom

Ok well I finally got my boat in the shop and was working on it trying to find out where my leak was coming from. After checking the bellows and other items I found that one of my bottom transom plate bolts was about a quarter of the way loose. I haven't put it in the water to check it yet, but I'm almost certain that is why it was leaking. Thanks for everyones help and advice.
 

Junkiexp

Seaman Apprentice
Joined
Jun 11, 2010
Messages
31
Re: Leak around the transom

But why is it loose, thats the question you have to ask yourself.
 

Fishermark

Vice Admiral
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Oct 19, 2003
Messages
5,617
Re: Leak around the transom

one of my bottom transom plate bolts was about a quarter of the way loose.

I've never seen one simply come loose. I have seen them get loose because the transom was rotten and soft enough to compress.... that causes the bolt(s) to be loose. Sorry. :(
 

fishrdan

Admiral
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Jan 25, 2008
Messages
6,989
Re: Leak around the transom

What are you working on there, a Mercruiser yes, but what is the year or better yet, what is the S/N?

I found that one of my bottom transom plate bolts was about a quarter of the way loose.

My .02$ guess is the lower bolt is corroded and broken. If that's the case, I bet the transom is shot.

But, that's just a guess as we don't know exactly what you are working on; M1, Alpha1, Alpha1 GenII, Bravo 1-2-3 :confused:
 

Jamz3333

Seaman
Joined
Oct 12, 2010
Messages
72
Re: Leak around the transom

It is a mercruiser alpha one gen 2. I have never dealt with a rotten transom but when I tightened the bolt up the transom didn't give at all it just tightened back up. I'm not sure if that means anything or not. It is also a 1991.
 
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