Transom Plate Water Leak

[davebuc]

Hi,
I am trying to get a sense of what's causing this water leak.
23' Glastron
5.7 Mercruiser
Alpha One Outdrive
The slow stream of water enters the boat at the bottom and center of the inner transom plate between it and the transom wood.
All my bellows were new in August 2009. In July of 2010, I hit a rock, taking the skeg off the bottom of the lower unit. Local Shop pulled drive, checked everything out at that time when lower unit was replaced. Water accumulating in the bilge seems more this Spring than what I remember last Fall.
The bolts on the transom plate are not super tight. I could turn them each another full rotation with a wrench if this would help.

Thank you,
Dave

 

[Bondo]

Re: Transom Plate Water Leak

The bolts on the transom plate are not super tight. I could turn them each another full rotation with a wrench if this would help.

Ayuh,... Sorry Dave, but the odds are, the transom wood is Rotten, causing yer problem...

Tightening the bolts ain't gonna fix it...

 

[Fishermark]

Re: Transom Plate Water Leak

Well Dave, sorry to be the bearer of bad news, but you have a rotten transom.

The wood has turned soft and allowed the transom bolts to be loose. The only real solution is to rebuild the transom. You can verify by drilling small holes inside near the bottom. You will find wet mush instead of dry sawdust.

 

[davebuc]

Re: Transom Plate Water Leak

Hmmmm..just got back from the boat.

Drilling small holes around the transom plate produced sawdust, even right next to the spot where the water comes in. Perhaps the rot is minor and contained to the edges of the transom cut-out? Perhaps the problem is something else?

 

[davebuc]

Re: Transom Plate Water Leak

btw, I also took a box-end wrench and banged on the transom all over it. The sound is the same throughout, and I did not hear that dull thud-like sound I have heard in YouTube vids of people banging a wrench on Rotten Transoms and Stringers

 

[Bifflefan]

Re: Transom Plate Water Leak

While I do agree with the others about the transom being bad, it could be where the exhaust bolts to the transom plate. If thats loose or the O-ring is bad it will leak the same way.
Try these things.
1) run the boat in the driveway on the hose and see if you get water in the bilge. If yes, possible an exhaust problem.
2) Make sure the bilge is dry, put the boat in the water but do not start it. Just let it sit for an hour, then check the bilge for water. If yes, probably transom.
One of these should produce a result. To fix either you have to pull the engine, so you have that to look forward to.
I had to to both last year, I have pics posted of this in my profile. Feel free to take a look.
Good luck.

 

[Silverbullet555]

Re: Transom Plate Water Leak

I'm going to say your pulling the engine. I'm getting ready to do the same.

May not have rot, but if not repaired correctly, you will.

Before doing that I would do as suggested and run on the muffs to see if you get water in the bilge then put the boat in the water without running it. That could help you determine the problem area as the motor/exhaust or water coming through the transom.

 

[Bt Doctur]

Re: Transom Plate Water Leak

pull the drive first to check the boot for water, inspect the shift boot for cracks/tears,
could be the Y pipe had corroded thru , if these are eliminated than a rotted transom is the suspect.
A severe strike could have loosened the outer plate, but the only way to be sure is spraying with a hose from the outside, looking for drips inside.Only fix is to remove the motor and transom and re-install using a new gasket.

 

[davebuc]

Re: Transom Plate Water Leak

Ahhh,
When I originally found the leak, it was having just put the boat in the water, not having run the engine. I will run it with the muffs and see what that gets me.

Today I put the plug in and filled the bilge with water up to 1.5" above the bottom of the inner transom plate. I went to the stern of the boat and pushed and pulled on the outdrive, especially trying to lift it upward. No water came out the back of the boat anywhere. Perhaps the transom leaks above the point to which I filled the bilge?

dave

 

[Bifflefan]

Re: Transom Plate Water Leak

Ahhh,
When I originally found the leak, it was having just put the boat in the water, not having run the engine.

But was it dry before you put in? Are you positive?

Today I put the plug in and filled the bilge with water up to 1.5" above the bottom of the inner transom plate.

Thats not the same pressures. And plain just not a good idea.

 

[davebuc]

Re: Transom Plate Water Leak

But was it dry before you put in? Are you positive?

Yes. With the boat dry on the ramp, I got in the bilge, and dried any water, let the boat sit for a minute to make sure that no more appeared and then had my wife back the boat into the water while I laid in the side of the bilge, and watched the water come in at the bottom center of the transom plate.

 

[Bt Doctur]

Re: Transom Plate Water Leak

page 23 has a pic of the inner plate, not many places to leak water.
exaust
shift boot
bellows
trim/tilt wiring
trim/tilt hyd. connector block/gasket
water inlet tube
speedo inlet
http://www.boatfix.com/merc/Install/gas/86419602.pdf

 

[Brentathon]

Re: Transom Plate Water Leak

Don't forget the possibility of an Upper Swivel Shaft Seal leaking.......although, you would have to have a "stern heavy" boat, where this seal is sometimes below waterline.

 

[davebuc]

Re: Transom Plate Water Leak

I was finally able to pull the outdrive and engine...

Those betting on "rotten transom" are the winners.

I still need to figure out where the water leak is / was that caused this.

For now, I am focused on chiseling out the rotten transom wood down to the fiberglass skin.