LEAKING IN FROM LOWER TRANSOM PLATE BUT NOT ROTTED

[appel1978]

OK so title says not rotted but Im not 100% sure that that would be the cause. I have tapped around the transom with ball pin hammer and its has solid spring and doesnt have flat sound or rotted. The fallowing is what ive done so far.
Took the outdrive off and there was lots of water in the gimbal area with lots of calcium build up and rust on knuckles so im assuming this has been leaking for a while. I am replacing the gimbal bearing and seal obviously along with all gaskets, bellows water inlet hose and o-rings. While im in there im changing out the shift cable. If anyone thinks i should do anything else then let me know.
Ok so that all being said do you think the gasket or bellows was the cause of the water leaking in from the bottom transom plate drain hole? Or do you think i have a rotten transom? I took a hammer and tapped all around and got solid spring back from the taps so dont sound like any dead spots. But the only way that i can tell in transom is rotted is to remove motor and look behind transom plate from inside. And I REALLY dont want to do that just to find out its fine. Any suggestions? Also there is a very very tiny pin hole at bottom corner of the part of the outdrive that is attached to the transom it self is that normal or if not can i repair that with some form of epoxy from the outside without removing it. Because i again might need to remove engine to do that.
Pic is of where water is coming in through the drain hole (NOT to be confused with drain plug which the hole is directly above by a few inches) on the lower transom plate. from what im told this holw is to let water out that has gotten between transome to help prevent rot.

 

[kenny nunez]

If it was possible to watch the leak and it was coming from a higher spot just under the drive shaft then the source will be the bellows. Now if the transom was soft this is also where water will show.
You can try to check some of the nuts inside the transom that you can reach. If any are real loose you might get by for the season by tightening them, and seating around the outer plate.
Good luck

 

[rickasbury]

I have an express cruiser and had a leak from the transom asy. I have a mercruiser i/o. I did have to pull the motor, clean everything up and re assemble. The seal design kind of sucks...but it seems to be fine now...ruff job!

 

[appel1978]

Still leaking but really narrowed it down.
Ok so what I've done so far.
New
* bellows
* Lower Shift Cable
* tore apart entire stern drive replaced all seals and gaskets
* pretty sure I did all seals and gaskets on transom assembly
* new gimble bearing and seal
* removed old caulking and replaced around transome assembly

Think that's it and still leaks just as bad as before. Transom is a little soft only bottom right corner. Just on edge of assembly hole. If I SQUEEZE my hand down there i can feel its soft on inside edge but ita still farely strong only a inch or two in from edge. but there is no way itscoming from there. With the new 3m marine adhesive 5200 that **** isn't letting anything in even of transome was rotted badly not at least the first dip to test at ramp.

So here is where I'm at leaks just as bad as before which is a steady stream through hole not a small drip. Can't be from any of the things I replaced. Can't be transom (at least te outside edge). I found out that it is leaking just about where the exhaust bellow opening on transome. I found this out by slowly putting it in inch by inch and checking for leaks. It just started dripping not pouring yet but dripping at that point. Is there a gasket between outer transome assembly and how the exhaust meets up inside boat and is there a way for water to leak there. The only other place it would be leaking that low would be the hole for the shift cable BUT that hole should have still been just above the where the water line was at the time of the test

 

[Bondo]

Ayuh,..... As I mentioned over at that other forum,......
It is possible that the shutters got damaged, dropped into the y-pipe, 'n the bits wore a hole through the y-pipe casting,.....

 

[Horigan]

Pull the drive and look in the exhaust port for signs of old flappers or other debris. The surfaces should look relatively smooth. Then put some water flow with a hose in the exhaust outlet (not so much that it goes up the risers and into the exhaust manifolds) and look for any water coming into the boat. The water should only come back out the exhaust outlet.

The shift cable enters the boat through an interior hose that extends up behind the engine and well above the water line. It's possible the leak source is where this hose connects to the transom.

 

[appel1978]

Exhaust pipe flange was broken on one corner so I'm bleeding that was it. I got it welded and new hole drilled. Put it back on torqued to 50lbs. Really didn't feel to tight but left it at 50lbs. New oring seal and gasket sealant before seal on transom assembly flange , on seal and on exhaust flange. It's still leaking just half as much. Did I over tighten it or do I need to tighten it more. I do have the 1990 omc so I might be wrong but I believe on this year I csb go tighter due to having helocoils on this year. Correct me if I'm wrong

 

[appel1978]

Ok so half the issue was the exhaust pipe obviously but I found under very close inspection a pin hole on the bottom corner of transom assembly. Wasn't sure it was leaking there till I had my daughter blow compressed air through it and I could see air flow from inside so if air is getting through water obviously is. So I think I finally narrowed down the last leak. Instead of buying a hole new/used assembly I'm just gonna use a dremel out the hole a little bigger and scuff it up then use JB Marine Weld to fill the hole and feather it out on outside the after that cures cover that with 3m Marine adhesive sealant 5200. That really should take care of it for as long as I own it. And if the 5200 ever gets compromised I'll just reapply or if need be buy the assembly then. I'll keep you all updated.

3M Marine Adhesive Sealant 5200​

 

[appel1978]

In these pics I first dremeled out the pin hole very slightly so I could push some Jb marine weld through the hole and then cover outside. Let that curw for a day and the I added a layer of the 3m marine adhesive 5200 (fast dry version) should be ready to get wet in 7 hours for hopefully the final leak test

 

[appel1978]

Finally No more leaks. So to recap, there is two faults, one pinhole in the bottom right corner of the transom assembly. And a broken nut on the bottom right side of the exhaust flange, both contributed to the leak. It did have a small leak when I bought the boat which Was originally probably the pen hole. I just wanted to make sure I came back and gave the final outcome. Too many time these threads get started and the OG poster never gets back after they fix it. The whole purpose of these forums are not only to get help for yourself but to help the next person who might benefit from you trials and errors. God bless you all.

 

[88 Capri (2022 SOTY)]

I'm glad you got her watertight, enjoy boating