transom leak

[Don't Panic!]

1987 Searay Seville 19', OMC 4.3 Cobra.

So after a minor freshen up last fall of new bellows and shift cable adjustments, the boat was taking on water. I could see when filling the bilge with water, it would drip out at the bottom of the transom seal. I assumed rotten transom, and slowly over the last few months have pulled things apart.

So where I am at now is I have the engine/outdrive out of the boat, have removed the transom plate, and everything has looked good every step of the way. There is no visible rot in the outdrive cutout. Whacking around with a hammer doesn't reveal any soft spots. A drill down into the core comes out nice and clean. There clearly are signs that water was making it's way past the transom seal, but no obvious explanation as to why.

I did not find any loose or missing bolts, and everything looks solid. That's all the good news. The bad part is what do I do? Just reinstall and hope it's ok?

What else should I replace/look at while in at this level?

 

[Scott Danforth]

tap test wont show anything (it never does)

never fill the bilge with water

where did you drill, and how deep? i would drill into the transom about an inch deep, up an inch from the inside of the hull, starting at 2" from the drain plug and moving outward every 4 inches.

post a pic of your keyhole and bilge

 

[Don't Panic!]

I drilled straight down into the plywood core of the keyhole about an inch. Will do more tests like you suggest and grab a few photo's tonight. It looks real clean.

 

[Don't Panic!]

I did a few test drills into the transom from the inside, it is solid. Here's a few pics (assuming I got the picture thing working...)

outside:
View attachment outside transom.jfif
inside close:
View attachment inside transom.jfif
inside further back:
View attachment inside transom farther back.jfif
clean shavings:


transom plate:
View attachment transom mount.jfif

 

[Don't Panic!]

so I got all the parts in I think I need to reassembly, I plan to get going on it this weekend. So far I only filled in the test holes with epoxy, and smeared a coat over the exposed wood in the keyhole.

I'm debating whether to install the transom seal dry, or with a sealant. Thinking of using a little of the Permatex stuff that is used on all the other bolts and gaskets. I thought briefly of putting in a bead of 5200, but that seems like a bad idea. Any thoughts?

 

[cptbill]

Did you look at the "Y" pipe and the seal for it really good? You probably did but just asking, I've had that problem before and it took me forever to figure it out, I thought oh no transom and as I was pulling the engine I found corrosion and a split seal. This was on a 5.7 gsi w/dps-m

 

[Don't Panic!]

so I finally got the transom plate back on, engine installed, and all the wiring/steering stuff back together. I was about to put the outdrive on when I saw a puddle of oil under the outdrive that had been sitting for a few months. It was hanging from the eye hook, but a bit loose and tilted forward a little. Nothing more than it would be if it were on the boat though. I hoisted it up by the eye hook till it was hanging, and more oil drained out through the prop.

This does not seem good... I've never had a leak here before, could this happen from sitting off the boat in the garage for a few months? So frustrating, thought I was almost done.

I assume a bad prop seal? Is there something else I should check first before assuming that?

 

[Don't Panic!]

many months later...., I had someone do a pressure test and take a look at the drive leg, he says it's definitely leaking (i know this, lol) but it is not coming through the seal at the prop. He thinks the bearing carrier, or lower leg housing, is cracked. His suggestion is to buy a new lower unit. This seems absurd to me, especially in light of the fact that I don't think I can even buy one. I've seen a few used legs, but folks who have them want a lot of $$.
Is a cracked lower bearing carrier a thing? What causes it? The leg was not leaking until it sat in my garage off the boat for about a year. What else could be the issue? Seems unlikely to me that it broke. I'm not buying a new leg, but would be willing to sink in some labor if it's a diy kind of thing. Any chance it's a seal between the upper and lower units or would the leak not manifest in this way?

 

[Bondo]

I had someone do a pressure test and take a look at the drive leg, he says it's definitely leaking (i know this, lol) but it is not coming through the seal at the prop. He thinks the bearing carrier, or lower leg housing, is cracked. His suggestion is to buy a new lower unit. This seems absurd to me,

Ayuh,..... Sounds like the guy is a hack,......

With a spray bottle of soapy water he shoulda nailed down Exactly where it's leakin',.....

 

[Don't Panic!]

yeah, I was not impressed. He had some bad information about the OMC shifting issues too (that I already know about from researching it and adjusting everything last year).

It's rough right now, everyone is busy and doesn't want to work on old stuff. This guy was someone off Craigslist, no shops around are interested in working on my 35 year old boat with an obsolete drive unit. Go figure lol.

 

[hugh g]

I had a leak like you describe on my 3.0. Turned out to be prop seal. I had never done one but with an OMC shop manuel to guide me along I took care of it. I'm sure seal kits for your 4.3 are still available.

 

[hugh g]

yeah, I was not impressed. He had some bad information about the OMC shifting issues too (that I already know about from researching it and adjusting everything last year).

It's rough right now, everyone is busy and doesn't want to work on old stuff. This guy was someone off Craigslist, no shops around are interested in working on my 35 year old boat with an obsolete drive unit. Go figure lol.

The old timers who knew OMC are for the most part gone. The labor rate is the same on a 35 yr. old boat or a 2 yr old one. A lot of shops won't touch OMC because parts can be hard to source & the company is history.

 

[kenny nunez]

I might be the “O” ring that seals the shift shaft.

 

[Don't Panic!]

Just popped in here to research something and did not realize quite how long it's been since I took this thing apart! Anyway I finished putting a new SEI lower unit on it last weekend and it fired up with no leaks or weird noises on the earmuffs in the driveway. Just a few more small things and it'll be ready for another sea trial.

Turns out I could buy the SEI lower for less than it would cost someone local to go through the old Cobra and refresh all the seals. Crazy. The new one does shift a lot easier (just doing it by hand while turning the output shaft) and it spins smoother, so I do think something is funky in there. So I'm not too sad to just replace the whole lower unit. I am a bit pessimistically waiting to see what the next thing to fail is though... my money is on the carb needing a rebuild after sitting so long, but it started/idled fine so maybe I'll get lucky.

 

[Lou C]

Your transom basically looked like new, as if it was done a couple years ago!
I am also running a Cobra (original) and picked up a spare from ebay, about $950 for a nice one. Also have a spare transom mount complete with the trim rams etc.
I'll keep them going as long as I can then figure out what to swap it to, for however long I want to keep running this boat.

 

[Don't Panic!]

quick follow up. It's several months later and though I essentially did nothing to fix the leaking transom seal, it is better now. I did pull EVERYTHING out, and used a little shoe-goo around the new transom seal when installing it, and of course torqued everything nice and tight. I let the transom assembly sit for a few days and re-torqued before installing the engine (not on purpose, just how things went at that time) and am hopeful to get another few good years out of this boat.

I was meticulous about breaking in the new SEI lower unit, was kind of cool to cruise up and down the river at low speeds for a few hours. Never done that before! It's working great so far.

I've done a bunch of 1-2 hour rides so far and had exactly zero water in the bilge. Boat runs sweet, if not for the difficulty of shifting out of gear I'd be 100% happy.