What to use for sealing transom motor bolts

Scaaty

Scaaty

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Whats the best sealant for sticking in the bolt holes (with bolts) of mounting a motor? Two holes will be under water when sitting . Used to just use silicone, but I think there would be a possible separation issue. This will be a big old Tower of Power on a 16 foot Flatbottom, and it will rock and roll around back there a touch slamming back down on the waves, etc. I have some unopened 5200...don't know if thats right for this application.Thanks
 
Chinewalker

Chinewalker

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Re: What to use for sealing transom motor bolts

I've always used white LifeCaulk, as did the marina I used to work at...
- Scott
 
Mark42

Mark42

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Re: What to use for sealing transom motor bolts

Another product is Boat Life sealer. I used it on my motor mount bolts (40hp) three seasons ago. No sign of leaking. And it stays fairly flexable, won't get hard and brittle. It is designed to seal marine applications that you will have to get apart eventually. It is NOT silicone, and takes almost a full week to cure, but I think it is a great alternative to the adhesive type sealers.

Before you mount your motor, consider drilling the bolt holes 1" oversize. IE for a 5/8" bolt, drill a 1 5/8 hole. Then fill the hole with epoxy. Add filler to the epoxy if you like. Then after cure, drill the 5/8" mounting hole through the epoxy. That way, even if there is a leak around the bolts, the water cannot get inside the transom because of the solid epoxy "plug".
 
Plainsman

Plainsman

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Re: What to use for sealing transom motor bolts

3M 5200 is a permanent soluton, 4200 is not. I wold use the 4200 if that is the route you wish to go.

I like that idea mark. I am sure I will use it in the future.
 
M

ManOfwar690

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Re: What to use for sealing transom motor bolts

best to use cavasill and resin then a small patch of glass on both sides cavasil is a glass based powder that u mix with resin and just a drop of hardner and the fill the holes wiht putty knife pushing it in all the way thru one side to the outher so as not to get a void u dont have to glass it eather as ( cavasil) it is a permanant fix just gell coat with a waxed jell coat and done and for ever and is very cheep to do
 
Scaaty

Scaaty

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Re: What to use for sealing transom motor bolts

Thanks for the great replies, and Mark, thats GREAT idea! This has already had a Merc of it, with 2 piece aluminum transom plates, and the holes are there from before So its either LifeCaulk, Boat Life sealer, or 4200. Check it out when I stop by the boat store tomorrow. I didn't think 5200 was a good answer after reading the directions. Thanks again guys...Robby
 
A

andy6374

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Re: What to use for sealing transom motor bolts

Glad to see you are not going the 5200 route. 3m 101 is another way to go, it's the same stuff as life caulk
 
tomynoks

tomynoks

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Re: What to use for sealing transom motor bolts

Mark,

That's a GREAT idea!!! It's too bad I just finished rebuilding the transom on my '74 Starcraft today!! What luck! I'm not about to take it apart and start over. There's always next time though.
 
JasonJ

JasonJ

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Re: What to use for sealing transom motor bolts

Just use the 5200. I use it, it keeps the water out, and it is not so "permanent" that you can't get the bolts out. Whenever I wanted to remove the bolts I just remove the nuts and run the bolts out with a ratchet or air wrench. No big deal.
 
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