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landry

Help - leaking transom motor bolt!

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I am getting water through one of my lower motor bolts on my transom (75hp merc optimax and Crestliner combo).

I am pretty sure I caught it early.

When I got home I checked and it was loose and so were the other three!!! I mistakenly turned the others thinking I was tightening them and the bolts spun.

Now I am concerned I have broken the seals on those too.

Was thinking I could take out the bolts one at a time and reseal them with 3M 5200 after letting any wet wood dry.

Or should the motor be taken off and resealed all over again by a professional????

any advice/tips??????

Thanks so much

Landry

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Make some rubber washers from an old tire tube, tight on the bolt and put them between the motor mount and transom. I have never had a leak in 20+ years.

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Just get some 3M 5200 or Sikaflex Marine Sealant and seal em up. No biggy.

Make sure to seal outer and inner.

Loosen bolt, pull it out and put some 5200 on the shank and slide it back in.

put a bead around the bolt on the inside, reinstall the washer and nut and torque to about 50 FT LBs.

Done!!

Edited by DRIFTER_016

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Remove one bolt at a time, fill the hole with 3M 5200 from inside and outside, coat the bolt with the same sealant, insert and tighten the nut, use lock nuts if you can,

when tightening, only turn the nut, make sure the bolt does not turn. let the access sealant ooze out. leave to cure.

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Thanks guys. I will use 5200 and your tips.

Glad I caught this early - I think I did anyways - although I thought I noticed the wood a little darker on that bolt last fall.

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Do u think I should soak in some sort of thinned epoxy or sealant in the wet hole once it is dried as an extra measure???

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Ok. Thanks again.

I'm gonna try to dry it out first for a few days with some heat cause I will worry otherwise. The bolt is exposed and not sandwiched by aluminum which will likely help.

There is no flex in my transom. Hopefully all is good.

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There was very little 5200 in the hole and none on the bolt or inside washer. Seems like Crestliner just put 5200 on outside edge of transom. Typical shortcut I am guessing.

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FishnSled just had his transom replaced on his Crestliner. The wood was soaked and the transom spongy.

if your is the same design, it will rot as well.

Crestliner puts a metal cap across the top of the transom, but does not seal the cap. After years of use, water splashing up would make it's way into the top of the transom and get stuck there.

It yours is the same design, I would highly recommend that you remove the cap, seal it with either a rubber gasket or calking.

HH

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I use 3M 4200 as opposed to the 5200. The 5200 is extremely adhesive and has tremendous tensile strength. That is not required for this application and can lead to damage when trying to remove it. The 4200 series has the exact sealing properties with 1/3 the tensile strength. This makes motor removal easier and safer later on. It also means the sealant is easier t get off the transom. Numerous examples of V6 outboards holding in place after the bolts have been removed using 5200. I just added a jackplate and used the 4200 with a 200hp. Up to you, but I'd google it first.

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Like previously said, use of 3m5200 and you're going to need one mother of a nut buster to undo it, 3m4200 is a little less tensile.

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Just went through this myself. Used 5200 as advised by OFC and worked perfect. 5200 has a long cute time. I was down to the hour before my fishing trip

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I resealed all the motor bolts today. Did one at a time and used 3M 4200. Put the lower bolts in from the outside as recommended by Mercury site. This way sealer is pushed inward into the hull. We generously slathered the bolts up and pushed them so that the excess would fill any voids on the motor mounting bracket.

I didn't put sealant in the holes first and now am second guessing myself. Should I be?

Edited by landry

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You should be ok as long as holes are sealed from outside,

I would have filled the hole from both sides first,

Sealant is cheap. And it's no good for next time once you open the tube.

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Redid all 4 holes today with sealant in holes first. I am sure they are watertight now.

Hopefully my transom is all good. Didn't see any rot in holes but there is about an 1/8"gap between wood and aluminum so I hope that is not due to delamination.

Gonna have it inspected this summer. Fish sled told me that The Crestliner transom caps are apparently not sealed. Hopefully I don't have rot there.

 

Thanks to Fishnsled and everyone else for their help.

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If you didn't see any then there is no rot,

At least the inside wood is exposed and you can air it out after each outing, just leave the back hatches open when not in use,

I know what you mean by transome cap not being sealed, but my boat is 12 years old and no sign of leak anywhere around transom cap,

Another spot to look is around the scuppers, there are 2 pieces on each scupper, just pushed in from either side, mine leaked when the boat was new, l pulled them out and reinstalled with 3M 5200,

You might not have the same design.

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