Alpha one transom plate gasket replacement?

[Fiat4Fun]

I have a 1986 Mercruiser with a 260HP motor and alpha one. I am getting a bit of water in the bilge, and can't see where it's coming from. The bellows have all been replaced, and wondering if the transom plate gasket is something that should be changed after a certain time or hours? Boat has about 900 hours on it. I doubt the transom plate has ever been removed.
Just wondering if this is considered a maintenance item?
Any advice would be great
Thanks

 

[Scott Danforth]

99% sure its a rotten transom on your 33 year old boat vs the transom gasket.

put boat in the water, get back there with mirrors, camera, etc. and look. lower the drive down to the point you hit bottom and lift the back of the boat a bit with the motor. if the leak increases, most likely you have a soft transom.

 

[alldodge]

Agree, if gasket is leaking then the transom is soft. Take a phillips screw driver and try had to push it into the inside of the hull around the motor. If screw driver goes in its soft

If it turns out to be solid look at the trim line manifold, also the upper steering pin.

 

[Fiat4Fun]

Thanks so much for your response. I did try the screw driver and tried with a pick, and it would not go in. There is glass inside the transom ( Chris Craft) , so i pushed pretty hard. Took it by a mercruiser dealer when it was on the trailer, and he moved the drive around, up and down, and didn't think the transom was soft. He thought that maybe when the prop hit a rock it might of dislodged the seal a bit? I have looked everywhere to see water come in, and so far nothing. I did replace the clamp on the shift cable boot, as he thought that might be a issue. It seem to of helped,
Never thought about the trim manifold. I thought that went through the drive not the transom???
Thanks

 

[alldodge]

The trim lines go from inside to outside the boat, so they go thru the transom. There is more then one seal there depending on if you have a mercathode or not

 

[Fiat4Fun]

interesting......
Will go out and check that out..... Does the rubber seal wear out? Is it obvious? Is this something that should be replaced every so often? I need to get a inspection camera down there to see when it's in the water. Can it be seen from inside if there is a leak at this point on the transom?

 

[alldodge]

It normally does not wear out, but some will corroded enough to start leaking. Might see a seep leak at the bottom of the key hole. Only way it will be obvious is if its leaking quite a bit