Opinion on Sealing Leak Around Thru-Hull Exhaust Fitting

[Judge]

My boat was water-tight during the first 15-hours of use.... even after I installed Lectrotabs and a Garmin transducer before the boat ever hit the water. Then after about 15 hours I started getting water in the bilge. It was happening when the boat was tied up to the dock more than when I was underway.

I started worrying my Lectrotab or Transducer install was the cause but after close inspection everything I did is water tight. But today I think I found the culprit. I had the marina take my boat off the storage rack and put it on a maintenance rack so I could do a few things. As I was looking around the back of the boat around the transom, I think I found my leak problem.

I saw something that looked like a stick hanging out of the starboard exhaust port. Upon further inspection I found it was a large piece of of sealant that was pulling out around the thru-hull exhaust port and transom next to the pump. It is about a 6" long section so this has to be where the water started coming from all of a sudden.

I took some of the bees wax I had and tried to force it in around the exhaust port where the sealant was pulling out at the transom as a temporary fix. I'm hoping my YES warranty will cover this since I am past the initial 12-month warranty so I can have the dealer handle it. If YES won't cover it, I may just try taking some 4200 and putting a bead around the exhaust port. Trouble is that it is fairly tight in that area to get good access because of the pump.

I can't pull the pump myself to get better access because we are not allowed to do major work at the marina and I no longer have access to do it anywhere at home. I could probably use a syringe filled with some black 4200 fast cure or use a brush to brush it around the fitting and get it sealed up fairly well.

According to the schematics there is an "Exhaust Valve" which seems to be held into a "Thru-hull Exhaust" elbow by three bolts. The schematics doesn't show a gasket or sealant between the exhaust valve and the thruss-hull elbow so I have to assume the sealant I found hanging out is sealing the thru-hull elbow.

But the more I think about it..... I may just remove the loose sealant..... clean the area as good as I can.... and then take some 4200 with a brush and brush it around where the exhaust fitting comes through the hull. That should seal it up permanently.

Anyone ever have a leak with the thru-hull exhaust fittings or have an opinion on my thoughts of brushing fast-cure 4200 around the thru-hull fitting to try and seal it up? Or just have the dealer look at it?

I'm one of those guys who tends to do his own repairs whenever possible and use the dealer as a last resort or to maintain the warranty integrity.

 

[Murf'n'surf]

Your dealer should repair any thru-hull fittings if they are leaking because once you seal it, YOU assume responsibility. Let them fix it under warranty.

 

[Judge]

Your dealer should repair any thru-hull fittings if they are leaking because once you seal it, YOU assume responsibility. Let them fix it under warranty.

That's what I was thinking originally..... just not sure if that will be covered under YES or not.

I will probably ask them and show them the pictures I took and see what they say about it.

 

[Dixemon]

Lots of folks here have witnessed the AKA "afterbirth" on there boats. I believe it to be understood that it is normal. I never have really made the determination that it was a leak source because we don't keep the boat in the water that often. So I contribute any water entry to the other usual suspects. It would be really cool if you could video the water coming in from those exhaust outlets from inside the clean-out access hatch. It would be interesting to see what your dealer says about it.

 

[Judge]

Lots of folks here have witnessed the AKA "afterbirth" on there boats. I believe it to be understood that it is normal. I never have really made the determination that it was a leak source because we don't keep the boat in the water that often. So I contribute any water entry to the other usual suspects. It would be really cool if you could video the water coming in from those exhaust outlets from inside the clean-out access hatch. It would be interesting to see what your dealer says about it.

So here's the $64,000 question.......

This "afterbirth" seems to be regular marine sealant based on its texture. This type of marine sealant is not meant to be used below the water line so why would they be using it there?

Why wouldn't Yamaha be used 4200 (on the off chance the exhaust port has to be removed) or even 5200 since it is likely the exhaust port would never need to be removed?

 

[Murf'n'surf]

The sealant is likely approved for its use. There may be an issue with the 3M sealants and heat, therefore its not used in the exhaust.

 

[Scottintexas]

Then after about 15 hours I started getting water in the bilge. It was happening when the boat was tied up to the dock more than when I was underway.

how much water are we talking about, is your bilge pumping water ? do you remove the manhole cover and see some water down there ??

as stated above,, there are many posts about excess silicone working it's way out of the exhaust, we've not heard that it's caused any issues, it could be that your's tore and did in fact cause a leak but that's not what we've seen in the past,

are you sure the garboard drain plug isn't the culprit ??

if it's mainly happening when docked you could take and spread some powder in the bilge to maybe help see where the leak is coming from,

 

[Judge]

how much water are we talking about, is your bilge pumping water ? do you remove the manhole cover and see some water down there ??

as stated above,, there are many posts about excess silicone working it's way out of the exhaust, we've not heard that it's caused any issues, it could be that your's tore and did in fact cause a leak but that's not what we've seen in the past,

are you sure the garboard drain plug isn't the culprit ??

if it's mainly happening when docked you could take and spread some powder in the bilge to maybe help see where the leak is coming from,

It has become intermittent. When ti first happened I was getting a gallon out ever 15 - 20 minutes. Over the past few weeks it is far less than that amount and frequency.

I can see quite a bit area on the starboard side when I pull the inspection covers and things appear dry. I can several of the screws from jy Lectrotabs and they are all dry. I can't see every screw for my trim tabs but all the ones I see are dry so I am 99% sure the water is not coming from them.

I thought I could see a little water on the port side but it is much difficult to see inside on that side that way it is laid out.

I will have to do some more looking around to see if I can find where water may be coming from.

 

[Judge]

So an interesting twist to the leak I was chasing in this thread.

I'm getting ready to schedule my 50-hour service and was going to have the dealer look for the leak. I'm at 58 hours and figured I would take it in between 60 - 65 since the first service was at 15 hours. I was also following a thread about another 275 that was taking on much more water than I was so I was going to have the dealer look at something the other 275 owner found.

I haven't been out in the boat too much this winter because El Nino put a real damper on boating in Southwest Florida with a lot of rain for the dry season and much cooler temps than normal. We have also been doing some remodeling so that has dry docked me as well.

The last time I had the boat out was about a month ago. As has been the case the past few months after my 15-hour service...... when they took the boat off the rack and launched it for me when I got down to the boat I hit the bilge and a fair amount of water was pumping out for the short time it was in the water. As the day wore on there seemed to be less water getting into the bilge.... but some would still pump out. That was what I had been seing.

We have some family in town and yesterday was a beautiful day..... in the mid 80's with light winds so we hit the water. When I got down to the boat about 30 minutes after they launched it from the rack I hit the bilge pump....... and no water came out..... zilch! That hadn't happened since the first few times I took the boat out.

After we loaded up and started idling out of the channel about 15 - 20 minutes later I hit the pump again...... no water!

We cruised around for about 2 hours and then dropped the anchor for lunch. After floating for an hour or so I hit the pump...... no water!

It was pretty choppy on the way back to the marina and I had one big spray come over the bow that got us all pretty wet and a couple smaller ones. As we got back to the channel to get to the marina I hit the pump again...... I got a small amount of water out.... not that much because it was spitting in a short amount of time. But after being out for over 5 hours, I was pretty happy even though a little water came out.

Once we docked the wife and I spent about 30 minutes cleaning the boat with salt away and hosing down the interior and drying eveything. Before I had them put the boat on the rack I hit the pump one last time....... no water!


So I'm not sure what changed. I haven't done anything with the boat in the past month or two. Almost seems like something "swelled" and whatever was the issue sealed.

Or...... I'm wondering if the service tech over-greased the intermediate bearing during the 15-hour service and perhaps it was causing the seal to leak water into the bilge. Then after 40 hours of running the seal re-resealed itself? Could water leak in if the shaft was not turning because water was getting in when the engine wasn't running for sure.

Anyway..... I'm hoping to get out again next week so I'll see how things look again the next time in the water.

 

[FSH 210 Sport]

I forgot, is your rack storage indoor or outdoor?

Glad there was little to no water on your last outing either way!

 

[Judge]

I forgot, is your rack storage indoor or outdoor?

Glad there was little to no water on your last outing either way!

It is stored outdoors..... top rack...... cover on...... plug out...... each time it is stored.


Oh..... and the advantage of the top rack outside...... my solar setup is the bomb! I have had zero battery or battery power related issues in 6 months of never having my onboard charger plugged in!

 

[FSH 210 Sport]

Okay, it sounds like there is a possibility of the staff inadvertently getting water in your boat? Don’t they flush it and wash it down for you when you bring it back in each time ?

 

[Judge]

Okay, it sounds like there is a possibility of the staff inadvertently getting water in your boat? Don’t they flush it and wash it down for you when you bring it back in each time ?

Nope....... they only wash the boat hull form the rub-rails down. I've watched them washing the boats..... plus the drain plug is out as well.

They flush the engines as well but based on where the flush ports are located the water would run off the swim platform of there was a leak at their hose. I have also flushed the engines with Salt-Away a couple times and never had a problem with flushing leaks inside the bilge area.

I'm about 99.99% confident the staff is not getting water in the boat.

And.... there is no water coming from the engines themselves. They are bone dry when running or off.

After the 15 hour service I could pump it out..... wait 15 minutes.... and then get more water out of the bilge if I turned on the pump again. The boat was getting water in it from being.... in the water. Yesterday..... it was not.

 

[FSH 210 Sport]

Hmmmm well leaks don’t generally fix themselves…. Do you put the cover on before they take it to the stack or do they put it on and then take it to the stack?

 

[Judge]

I usually put it on halfway and they do the rest.

It has rained a ton the last month…. and the plug is out when stored anyway.

Plus…. I have had the boat put on a wash / maintenance / rack to clean it and there has never been anything in the bilge when it goes from the rack to a wash / maintenance rack.

On top of all that...... if I pump it out and then leave the boat in the water overnight, when I come back the dock is wet from the bilge running over night or when I hit the pump, I got a fair amount of water out the next day.

 

[FSH 210 Sport]

I usually put it on halfway and they do the rest.

It has rained a ton the last month…. and the plug is out when stored anyway.

Plus…. I have had the boat put on a wash / maintenance / rack to clean it and there has never been anything in the bilge when it goes from the rack to a wash / maintenance rack.

On top of all that...... if I pump it out and then leave the boat in the water overnight, when I come back the dock is wet from the bilge running over night or when I hit the pump, I got a fair amount of water out the next day.

Okay, did you ever seal up the anchor locker drain?

That much water coming in overnight is troubling.

If you suspect the exhaust flange, take a blue paper shop towel and lay it underneath the exhaust flange then check it later to see if water got onto it. This method is a good way to check for leaks as is tossing a little baby powder on the inner hull to see if water has passed over it. Have you checked the deck drain thru hull fitting and the associated clamps and hoses? The only other thru hull fitting I can think of besides the exhaust flanges is the transducer.

Looking at the pics in your first post, I think that string of silicone sealer is the excess of sealer that squished out during assembly on the inside of the flange that is exposed to the exhaust flow. There has been several people who have seen this, sometimes it’s a doughnut looking piece and it gets removed in the early hours of operation.

 

[Judge]

Took care of the anchor locker drain before it ever saw water. Same with the cup holders on the swim platform and anything else I didn’t trust Yamaha to seal well at the factory.

i know it’s not my trim tab installation because I can see more than half the screws and not a drop of water is coming from them.

I dropped the exhaust port as a possibility since most people said they also saw sealant coming off around them shortly aftet a few outings.

I’ll see if it stays dry next time I have it put in the water. I probably won’t be leaving it overnight for a while so that will be a key test if my next time out stays dry.

 

[FSH 210 Sport]

I found ALL of the cup holders on my boat were not sealed up and those were a source of water in the hull for me as I wash my boat down on the water before pulling it out for the day, or if things get messy on the boat, or it rains.

Your issue is quite vexing, but, once you find the source it will be an ah ha! moment.

 

[Judge]

I found ALL of the cup holders on my boat were not sealed up and those were a source of water in the hull for me as I wash my boat down on the water before pulling it out for the day, or if things get messy on the boat, or it rains.

Your issue is quite vexing, but, once you find the source it will be an ah ha! moment.

When I pulled my cupholders the sealing was horrible. I have mine sealed up very well now and they won't leak.

When I pulled them to clean off the factory sealant and reseal them, I found Yamaha did not put the drain tubes in so they will drain when water washes over the swimplatform. Instead they filled the void between the bottom of the cupholders and the swimplatform drain hole with 5200. I ended up putting a small diameter nylon tube thorough the 5200 and out the bottom of the swimplatform for them to drain. It works but they drain very sloooooooowly.

I may tell the dealer about it at my 50-hour service and see if YES will cover them doing it the way it was supppsed to be done at the factory.

 

[Judge]

So it's been two weeks since my last outing and we went out yesterday for a few hours. The bilge remained bone dry again. That's two in a row over a span of about two weeks..... and after doing or changing anything.

Something definitely was leaking fairly consistently and now its not. It was so repeatable after I had my first service at 15 hours and now I am at 60 hours. I'm getting ready to schedule my 50 hour service and was going to have them look for the leak but now I'm not going to bother with it.

In any case..... now that I have 60 hours on her I am pretty pleased overall with the boat. The layout is great for us and both motors are running well.... even though she's a gas hog. The computer consistently averages about 1.4MPG so I get about two outings between fill-ups. I've not sucked up any seaweed or anything else running in the Gulf and intercoastal so that's a bonus.

I do wish Yamaha would have changed to a closed loop cooling system like the Scarab so I didn't have to worry about the marina yard guys flushing it well enough to get all of the salt water out. Once a month or so I'll have them pull the boat off the rack and put it on a wash rack and I'll flush it with Salt-Away. Sometimes I notice the pressure is too low from some of their water outlets to get water flowing out the pissers. I'm going to get a garden hose Y-adapter off Amazon so next time I flush it I can tap into two different water outlets to try and get more water through the system when I flush it.