Mercruiser 120 G1 A1 - Transom Seal

[peters715]

On this particular outdrive, the trim limit switch is located in the top of the gimbal ring. The only practical way to replace this switch is to remove the gimbal ring. This turned out to be an adventure resulting in the complete removal of the outdrive from the stern.

That said, I am now in the reassembly phase. The replacement transom gasket I have is cork. Would there be harm in adding a bead of silicon or RTV to the mating surfaces of the gasket to aid in sealing? And if so, is there a proper or preferred sealant to use in this type of application?

 

[kenny nunez]

The cork gasket is a dry fit. Clean all surfaces with alcohol first. Do not use any sealer on it. After the housing is bolted on you can go around the housing with RTV if you want. Torque the mounting hardware to 10 ft. Lbs in stages several times to let the wood in the transom compress.
I hate to tell you this but it will be a miracle if the limit switch lasts more than a year. That is their life expectancy. They would die just after the 1 year warranty ended.

 

[peters715]

Any thoughts on what causes the switches failure?

 

[Scott Danforth]

Any thoughts on what causes the switches failure?

because they are cheaply made to meet what the market is willing to pay. no one wants to pay $400 for a switch that wont fail.

 

[peters715]

Thank you for that info.

 

[tank1949]

Any thoughts on what causes the switches failure?

age!

 

[peters715]

Thank you for the information. Kenny Nunez stated the switch fails in about one year. I don't think a one year old switch would be considered old, but I've been wrong more than once today.

 

[JASinIL2006]

Unless Alpha One Gen 1 switched fail at a dramatically different rate than Gen 2 switches, I think the one year life span may a bit of exaggeration. I'm starting my 12th season with the same boat and I've only replace the limit switch once. It probably depend a bit on the environment in which the boat is stored (e.g., trailered in a garage vs. moored in salt water).

 

[peters715]

Yes, I suspected some hyperbole was in play. I'm not sure where a point if failure may exist however I can take a guess or two where water could maybe get in. So I will use some RTV around those areas to enhance the sealing.

Thank you for your useful/helpful information.

 

[kenny nunez]

There are 2 pointed copper contact points with a inverted copper cup that connects them together, over the time the cup expands plus the marine environment does it’s thing.
The original trim control panels used the exact same contact buttons, sometime up to 67 -68.
I used to disassemble them, clean the points and fold the inverted cup inward which worked for a while with silicone grease. Every time the button gets pushed it tends to expand the inverted cup.