Leaking Transom - outboard mounting bolt...

[bigjimmcbob]

I normally trailer my boat, so it never sits more in the water than a fishing outing.

This weekend had her in continuously for 3 days.

With no rain, I noticed some water in the bilge. Maybe 1 or 2 liters for 12 hours in water.

 

It's a fiberglass boat, so the only holes I can think of are transom holes - 2 below water line mounting holes for the outboard, and the drain plug.

 

I troubleshooted the leak to the port side mounting bolt for the outboard. Not sure how long its been leaking (4 year old boat), but I haven't noticed any water from the bilge on the day trips before, so I suspect its a recent problem.

 

Can I fix this myself without having it sent in to remove the whole motor.

Can I just remove the bolt and put a bunch of 3m 101 in there to try to stop the leak?

 

If I do have to bring it in, seems like a simple job to me, remove the motor, clean the wholes reseal and remount the motor + test.

How many hours should this take?

 

thanks!

[DRIFTER_016]

A bunch of sealer in the hole and some under the washer on the inside should fix it up. I would do both lower bolt holes. You should leave the bolts out long enough for the core of the transom to dry out and then seal up. You don't want it rotting out on you.

[HTHM]

Check the transom VERY carefully. If it is at all wet, have it dried out completely before remounting the motor.

[bigjimmcbob]

Check the transom VERY carefully. If it is at all wet, have it dried out completely before remounting the motor.

 

So when I remove the bolt(s) inspect the hole and check the wood core if its wet, if so wait until dry, filler up with 301 sealant and the washers and re-bolt?

 

Can I assume if the wood core at the hole perimeter is dry the interior wood is also dry?

 

I think its only started this year and it's only been in the water for a few times.

 

I don't understand why anyone would trust just the sealant?

Wouldn't it be more professional to drill the holes slightly larger, 5200/4200M seal the hole and insert a bolt through hole stainless steel housing that is completely sealed. Then thread the bolts through that with a sealant. Just like the drain plug housing is done?

That way odds are water would never touch the wood core and you'd just have to seal the ends.

 

I guess if different motors have different mounting hole pattens, but how often do you replace a motor?

Edited July 4, 2010 by bigjimmcbob

[bigjimmcbob]

So when I remove the bolt(s) inspect the hole and check the wood core if its wet, if so wait until dry, filler up with 301 sealant and the washers and re-bolt?

 

Can I assume if the wood core at the hole perimeter is dry the interior wood is also dry?

 

I think its only started this year and it's only been in the water for a few times.

 

I don't understand why anyone would trust just the sealant?

Wouldn't it be more professional to drill the holes slightly larger, 5200/4200M seal the hole and insert a bolt through hole stainless steel housing that is completely sealed. Then thread the bolts through that with a sealant. Just like the drain plug housing is done?

That way odds are water would never touch the wood core and you'd just have to seal the ends.

 

I guess if different motors have different mounting hole pattens, but how often do you replace a motor?

 

Also do you know if I have to have a certain amount of torque on these mounting bolts?

 

thanks again!

Edited July 4, 2010 by bigjimmcbob

[NANUK]

Once you remove the bolts and are sure that the inner core is dry, fill the holes and cover the bolts with 3M 4200 adhesive, insert bolts and when tightening make sure you only turn the nuts NOT the bolts(very important), use flat over size washers inside the transom and regular size washers & lock nuts on the motor side, whatever adhesive oozes out just leave it alone, don't wipe it off, you can always cut off the access when dry, I wouldn't even bother.

those bolts will not leak again for the life of that boat.

[fish_fishburn]

As for torgue on your motor mounting bolts. Just snug them up firmly but don't tighten till your blue in the face. You can crack the gelcoat if you tighten too much.

[bigjimmcbob]

I removed the bolt, and the transom is a little wet. Just looks like wet wood, no rot in the hole.

I can see why the water penetrated. They drilled the hole about 1/2mm skewed to the upper left.

The proper size mounting bolt fits perfect but you can see the gel-coat is just ever so slightly not shown in the upper left part of the hole, its there but looks like the water path came from up there and penetrated around the bolt.

Also there didn't seem to be much 101 sealant around the bolt at all. Looks like to me they did a piss poor job of mounting this motor.

I'm gonna pull off the other one after and reseal it too just in case.

 

How long should it take to dry out that hole? Should I wait longer to ensure it'd dried. I have no clue how far the water has penetrated, my guess is not that far. (Been in the water a total of ~52hrs this year)