Leak At Bottom Of Transom

Stamey

Petty Officer 1st Class
Joined
Aug 7, 2010
Messages
286
I have a leak at the bottom of my transom, into the boat. This leak was happening last year but I didn't realize it was a transom leak, and it still leaks at about the same rate this year, after I have replaced all bellows in April. I used my snake inspection camera to try to see where its coming from and it look like it is leaking in through where the trim hoses go through the transom.It appears to be running out of the recess where the hoses go into the inside transom bracket, and down the transom to the bilge. Now, I can't be absolutely sure of where its coming from besides what I can see.

After googling images of the inside of the transom for a mercruiser I am wondering about the exhaust port, but am not sure. In an effort to test the exhaust port I plugged up the exhaust holes in the transom, that come out diagonally on either side, then, as I have the exhaust tube, I put a hose in that and turned it on a little, to try and fill up the cavity, pushing the exhaust tube up as much as possible to retain the water. I had the GF looking in the bilge to see if any water was coming in and she said there was not. Now, I do not know if this is a valid test, because I cannot see if the water level is getting high enough to cover all of the port area. I obviously do not want to completely seal off the exhaust hose because I don't want the water level getting high enough in the exhaust system to go into the engine.

Any ideas of where the water is getting in, and how to further test for it on the trailer will be appreciated. Note, I have tried filling the bilge with water to see if it leaks back out, and either I didn't get enough in there because I can't tilt the boat back far enough to keep from filling the entire bottom of the boat, or I was worried about getting to the to starter before I got the the level of the leak on the inside.

Thanks,
Chris
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,079
Re: Leak At Bottom Of Transom

I have a leak at the bottom of my transom, into the boat. This leak was happening last year but I didn't realize it was a transom leak, and it still leaks at about the same rate this year, after I have replaced all bellows in April. I used my snake inspection camera to try to see where its coming from and it look like it is leaking in through where the trim hoses go through the transom.It appears to be running out of the recess where the hoses go into the inside transom bracket, and down the transom to the bilge. Now, I can't be absolutely sure of where its coming from besides what I can see.

After googling images of the inside of the transom for a mercruiser I am wondering about the exhaust port, but am not sure. In an effort to test the exhaust port I plugged up the exhaust holes in the transom, that come out diagonally on either side, then, as I have the exhaust tube, I put a hose in that and turned it on a little, to try and fill up the cavity, pushing the exhaust tube up as much as possible to retain the water. I had the GF looking in the bilge to see if any water was coming in and she said there was not. Now, I do not know if this is a valid test, because I cannot see if the water level is getting high enough to cover all of the port area. I obviously do not want to completely seal off the exhaust hose because I don't want the water level getting high enough in the exhaust system to go into the engine.

Any ideas of where the water is getting in, and how to further test for it on the trailer will be appreciated. Note, I have tried filling the bilge with water to see if it leaks back out, and either I didn't get enough in there because I can't tilt the boat back far enough to keep from filling the entire bottom of the boat, or I was worried about getting to the to starter before I got the the level of the leak on the inside.

Thanks,
Chris

No, that's not any kinda valid Test,... Go pull yer spark plugs, 'n make Sure ya didn't flood the motor,...

There's a hyd. manifold under there, lay on yer back behind the hull on the trailer, 'n look Up,...
It's gasket could possibly be leakin',...

Another option is to back the hull into the water at the launch, 'n inspect it closely on the wagon,...

Given the vintage,... I'm guessin' yer gonna find a rotten transom,...
 

Stamey

Petty Officer 1st Class
Joined
Aug 7, 2010
Messages
286
Re: Leak At Bottom Of Transom

The test for a rotten transom is standing on the stern drive and bouncing a little, right? I have done that and there is no flex in the transom.
I am going to see if I can get more light down there to see what's going on better.

Thanks,
Chris
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,137
Re: Leak At Bottom Of Transom

Mine was the fitting plate for the trim hoses.easy fix!
Grub
 

Stamey

Petty Officer 1st Class
Joined
Aug 7, 2010
Messages
286
Re: Leak At Bottom Of Transom

Mine was the fitting plate for the trim hoses.easy fix!
Grub

Wow, I have looked at that block under the stern drive briefly, but was not aware that it could leak where it is mounted. This is good to know. I'm gonna be doing my best to get more light down there and snaking the camera back in to see if I can determine the exact location of the leak.

Thanks,
Chris
 

bone1960

Cadet
Joined
May 30, 2013
Messages
7
Re: Leak At Bottom Of Transom

try slapping some Gluvit around that block and maybe along the rivets at the bottom of the transom, stuff works great.
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,137
Re: Leak At Bottom Of Transom

You can see the block the trim hoses go to from the outside under the drive,right by the transom on the gimble housing.
Grub
 
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