Slow leak from motor bolt on transom

[Drewsky2010]

Hello everyone, my first post, forgive me if I'm in the wrong section. I have a 78 glastron Carlson, outboard motor (85 hp Johnson) and there is a slow leak. It is on the transom below the waterline where the motor is bolted on. I can provide pictures if that would help. Anyways, I need to stop this from leaking, because pulling the plug and gunning it to drain all the water is getting to be less and less fun :lol: I've done some research and saw there is a sealant by 3m either 4200 or 5200 that should work. Do I need to pull the bolt and then seal it, then put a new bolt in, or could I reseal what is already there, and not remove the bolt. I tried to get it off, but it looks like a bigger project than I thought. On the inside there is a bolt on top of a little plate, then there is a nut on the outside. I tried loosening the outside, but it just spun. The Looking for some advice thank you.

 

[jigngrub]

Re: Slow leak from motor bolt on transom

How long has this been leaking? Have you inspected your transom for rot? Any leaks on a transom should be taked seriously and a rot inspection should be thorough!

Just the introduction of water through the hole has already wet the wood on your transom, and it isn't going to dry out. The fiberglass laminations work just as well to hold water in as they do to keep water out unfortunately.

Check your transom for flex and check it for rot, if you really love your boat you may want to make plans to replace the transom in the very near future, the wet wood is going to turn into boat cancer if it hasn't already.

 

[bakerjw]

Re: Slow leak from motor bolt on transom

Water in the transom can be very bad news. Not trying to frighten you but it is a 1978 boat. Old boats and water often spell trouble.

I know that 5200 will seal just about anything. We used it quite a bit on an ocean going ship that I helped refit. When my restoration gets put back together, everything will be sealed with 5200.

 

[pckeen]

Re: Slow leak from motor bolt on transom

Loosen the bolt - seal both sides, re-tighten.

 

[jigngrub]

Re: Slow leak from motor bolt on transom

Loosen the bolt - seal both sides, re-tighten.

Yeah, boat rot just happens to other people eh?

 

[Bob_VT]

Re: Slow leak from motor bolt on transom

The 85 Johnson is held to the transom with 4 bolts. The two top bolts control the height of the motor. You can and should just remove the two bottom bolts and inspect inside the bolt holes. Since you are already getting water intrusion I imagine your transom is wet too. All of the bolts should be removed (One at a time) coated with sealant 5200 (which will cure when wet) and re-installed. You may have discovered the tip of the iceberg.........

 

[Drewsky2010]

Re: Slow leak from motor bolt on transom

Thanks for the help, it has been there most likely since I bought the boat 7 years ago, but is leaking a little more now. I used to think it was from water coming in over the sides of the boat but now I know it leaks even if no water comes in from splashing. I have seen just a tiny drip where the bolt is at.

The transom seems very stable without any sign of rot, at least from the outside. The outside nut on the boat has some rust and could probably use replacing. I'm worried if I force the bolt off, I don't want to make it worse. And I'm not entirely positive a can get the thing off. The nut and bolt head keep spinning but not loosening. Any tips for getting it off? Do I need to worry about stability with only 3 bolts after I remove one, or could I remove it, take the nut and bolt to lowes, then replace it.

 

[Drewsky2010]

Re: Slow leak from motor bolt on transom

Here are pictures. Just a little drip on the inside. Let me know if these pics do not work.

http://db.tt/klouojJ5
http://db.tt/NuADbHKs
http://db.tt/rAClzui7

 

[jbcurt00]

Re: Slow leak from motor bolt on transom

It looks to me like there's already been some attempt to stop water intrusion w/ caulk/sealant of some type behind both bolts you posted.

As already mentioned I too suspect that the water at the thru bolt is the tip of the iceberg.

You can cut the bolt head or nut off, tap the bolt thru the hole & take it to get 4 new sets. If you're pulling them to inspect the interior of the hole (which is IMPORTANT), apply sealant & reinstall, and you have to go to HD/Lowes to get at least 1 bolt/washers/nut setup anyway, 3 more won't be cost prohibitive. It'd be cheap insurance.

Doing them 1 at a time may be possible. Depends on what you find when you pull the 1 rusted~frozen 1.

Let's get these pix over here where their easy to see:

Typically you'd use a wrench on the outside bolt head & the inside nut to loosen a thru bolt & nut. They both just spin?

The outside nut on the boat has some rust and could probably use replacing. I'm worried if I force the bolt off, I don't want to make it worse. And I'm not entirely positive a can get the thing off. The nut and bolt head keep spinning but not loosening.

So the bolt is sheered off in between somewhere?

Hit the bolt threads w/ a wire brush to clean out the threads (don't damage the threads).

Tap the bolt end at the nut w/ a metal hammer, liberally apply the penetrating lube of your choice (WD40 wouldn't be my 1st choice, but most people have some) to the nut as best as you can to both sides of the nut, tap the bolt again a few times. Just enough to get a vibration thru the bolt, NOT enough to damage the threads on the end. Repeat several times thru out the day(s).

EDIT: redacted by request

A few cycles of tapping & lube might free up the nut enough to loosen it.

I suspect that if you pull that lower port thru bolt & carefully inspect the condition of the transom, you'll find that you should probably pull the motor off, and do a much more thorough inspection of the entire transom.

BTW: What's that washer looking plug above the lower bilge drain plug socket in the last pix I posted?

 

[Grub54891]

Re: Slow leak from motor bolt on transom

That washer looks to be an anode,strange place for one,but maby it's bonded from the inside.
Grub

 

[Bob_VT]

Re: Slow leak from motor bolt on transom

Okay..... here is the suggestion. The boat is out of the water. Go to a garage and ask a mechanic to use a cutting wheel (not a grinding wheel) to slice off the lower two bolts. Or ask the mechanics to remove them with an air gun.

The bolts are all 1/2" stainless steel (Should be SS) x 4" long. "most" good ace hardware stores will have them in stock and buy some new ones, lock nuts and washers.

DO NOT heat anything since it can hurt the aluminum motor frame and the fiberglass on the transom. I know it goes against what was said above but even a propane torch can destroy the aluminum motor mount and since the aluminum is so conductive it will trash the fiberglass too

BTW when you re-install (possibly after a transom rebuild) .......the engine bolts go from the outside in so the nuts and excess threads are hidden.


Have you tried to put your weight on the motor while it is tilted up? Does the transom flex?

 

[Drewsky2010]

Re: Slow leak from motor bolt on transom

Let me clarify, the bolt and nut are frozen, and I can't get them to budge. I'm going to borrow a bigger wrench to see if I can get it off.

 

[Woodonglass]

Re: Slow leak from motor bolt on transom

If you know someone that has an impact driver I suspect it would make easy work of removing that bolt. Bob_VT suggestion to bounce on the Motor to see if the transom flexes is a good one. I'd also recommend drilling into the transom with a 1/4" drill bit and check the shavings. If they're dry then OK, but if they're dark and wet then you're prolly gunna need to replace the transom. If it flexes when you bounce on the motor then for sure you're gunna need to replace it.

 

[metriccrescentwrench]

Re: Slow leak from motor bolt on transom

I'd also recommend drilling into the transom with a 1/4" drill bit and check the shavings....

From the INSIDE of course.

From what you've described I'm betting on a wet/rotting transom. Been there/done that too many times now, it's just a fact of life with boats that unless any bolt or screw penetration into the transom is perfectly sealed you're going to get water into the wood.

 

[Drewsky2010]

Re: Slow leak from motor bolt on transom

That washer looks to be an anode,strange place for one,but maby it's bonded from the inside.
Grub

I am not sure what that is there, but it sort of appears to be some sort of ground. On the other side there is a wire attached to it. I've never had any problems from it.

 

[Coxwain]

any updates to this thread? What did you end up discovering or doing?

 

[GA_Boater]

any updates to this thread? What did you end up discovering or doing?

No. Closed, its ancient.