WATER, WATER AND MORE WATER. Transom leak at exhaust, Please Help.

[covertcombatant]

So yesterday we were out for the boats maiden voyage on the lake. Everything seemed to be fine, the carb would load up at idle so I knew I needed to adjust the carb. Had fun otherwise.

When we got back to the launch ramp and pulled the boat out I noticed we had taken on what seemed like an enormous amount of water. The bilge never kicked in on auto and the manual wasn't working. No big deal I'll fix it.
So today I go with the vacuum guage and go to tune the carb with the boat in the water with it on the trailer. I pulled the dog house, rear seat and rear cover over drive Shaft so I could see everything. So I get the carb tuned, and notice water coming in fast in the bilge area but it's coming from the drivers side stringer under the floorboard where the plastic foot rest it. It's coming out of a chrome tube and it's flowing pretty good. I finally realize that it must be an exhaust leak and it's filling the drivers side stringer with a ton of water. I did notice that the drivers side seemed a little heavy yesterday but figured it must have been my big lunch.

Now my question is I got home and tore the back seat out. I see the gas tank which is full of fuel and a plastic looking black box underneath it. That black box is surrounded by water. Can anyone guess what my problem could be.
The water is trapped in the stringer and not leaking back out of the boat where the exhaust comes out of the transom so I can assume I'm not taking on water there and that it muse be from the exhaust. Any help would be appreciated.

It's hard to see in the photo but that's the black box surrounded by water.

[Jetlink]

Can you take another picture further away so we can get a better reference. My first reaction is that your thru hull exhaust is not sealed properly. Before you go sealing it up though, make sure you get as much water out of there as possible first.

Again, a broader angle picture will help as well.

[covertcombatant]

Here is the drivers side rear transom. Water is not leaking back out of the transom to exhaust coupler so I'm hoping it's not the seals that go through. I wasn't able to attack this project till right now and got the gas tank and everything out of the way.

Has anyone ran straight stainless pipe instead of the (mufflers) / resonators?
I'm hoping that those are the problem since it would be a simpler fix. Let me know what you think. As always thanks everyone for your help.

First thing in the morning I'm going to run the boat down the street and throw her in the water and see where the source is. Just started raining, lucky me.

[Cusefan78]

Check the bottom side of the silencer. Last year one of mine had a small opening from it rubbing around over the years. I had the same deal. Water coming in on one side. They can be repair with resin

[covertcombatant]

What kind of resin did you use for it?

[Cusefan78]

3m all purpose. Had some laying around. Has held up with zero problems

[covertcombatant]

So here is a video of the boat in the driveway running with the raw water put into a bucket. Doesn't seem like anything is leaking that I could see.

https://youtu.be/7L_TzxT7uLI

[covertcombatant]

Here is video of it on the launch ramp at a pretty steep angle. Sucking water from the lake and the boat submerged. Didn't see anywhere at the rear where it could be leaking and coming in. At the end of the video you can see water coming out of the chrome tube that connects under to the drivers floor. Possible that the bow foam is saturated and when at a steep angle is draining back to the drivers side area? Going to have to throw it back on the launch ramp and see where the water is draining from without the black tray in the way.
Here is the video
https://youtu.be/kFZxwmHsug0

[covertcombatant]

I think the water that was spritzing was just the water that was trapped and the vibrations making it do that. It never really got higher.

Still curious about the bow foam and maybe that it's saturated and leaking back down.

[covertcombatant]

Ok, so digging deeper. The boat has a heater in the bow, maybe that is leaking. Time to climb under and check it out

[covertcombatant]

So it doesn't seem to be leaking from the heater. Might go get 5/8 heater hose plugs and just plug it anyway.
Under the drivers feet is where there is quite a bit of water. When I push on the floor under the black plastic tray, you can hear water. Carpet almost up to the front of the bow is wet. Nothing on the side is wet up the wall.

[Jetlink]

Is your bilge hose all intact? I know it sounds like a silly question but that area is below where the bilge hose is routed. Also, if you have wet carpet under the helm side of the ski locker divider, that foam goes all the way up to where the chines start from the bow and run down below the floor. That is usually where a bunch of water will pool in the foam and just sit there and fester because it has nowhere to go.

[covertcombatant]

I did check the bilge hose when I was under there and saw it. I laughed cause it would have been funny If it was that easy. But it's me and nothing could be that simple. Going to take it back to the launch ramp in a little bit and see if I leave it at a steep angle if that water drains that way. I'm wondering if it filled with water when the previous owner had it. And it's just stuck up there. I'm hoping that's the case and I will maybe put a 3 inch hole under the bow and suck all the water out. I don't know what to think right now.

[2500HD]

A couple of other thoughts are the caulking between the cap and hull as well as the bow loop for tie down on the trailer. I had a boat that the loop was not tight and it let in a surprising amount of water.

[Jetlink]

Good luck sucking up any water with a wet vac. You could spend months applying suction and still not get it all out. The only way to remove water from foam is to remove said foam. Sorry if that is not what you were hoping to hear but that is most likely the case.

[covertcombatant]

Thanks 2500 I will check that when I get home.

Jetlink, I had a sneaky suspicion that was the case. I'm just really surprised by the amount of water in the boat with what seems like no rot anywhere. Everything feels pretty damn solid as far as the floors and the stringers. So I don't know if the problem is recent or has been there for awhile. Thanks for all your help.
Is there any chance that the exhaust can leak from where it connects to the pipe that runs under the floor? Is that solid or is there connectors under the floor that can fail?

[Jetlink]

I'm just really surprised by the amount of water in the boat with what seems like no rot anywhere. Everything feels pretty damn solid as far as the floors and the stringers.

I'll stop you right there. There is rot, the problem is that the very thing that caused the rot is also masking it right now. If I were to bet, your floor feels solid because it was either redone, just the floor or you are walking on rotted wood that is now being supported by the water logged foam. Do your engine bolts tighten into your stringers?

[covertcombatant]

Motor mounts "seem" solid. You can torque down on them and it bites into the wood. Same with the transmission mounts and the gas tank straps. Everything has been sealed with some sort of caulking or epoxy where the bolts go in to the wood. I bought this from the original owner and have the original purchase receipt from the Los Angeles boat show in 1988. He never mentioned of the floors being redone, I'm going to call him today and ask.

[K_Dubbs]

Did you find the leak? If not take the boat out have some fun let it fill up. Do not pull the plug or run the bilge(if you fixed that yet) Dry the outside of the hull and wait until you find the smoking gun. First suspicion is check all the running gear. If after some time it does not reveal itself it is coming from inside the boat I.e. exhaust manifolds, water pump heater..... good luck keep us posted

[Salty87]

Temperature of the water will tell you if it's coming in from the lake or engine/exhaust. You could also fire it up on the hose and see if the level gets higher. If it's not the exhaust then it's the lake otherwise the engine would pump water into the main bilge channel. Do you have flaps or traps on the transom? The platform brackets on a comp are probably below the floor level. Check the brackets to see if they're attached to the transom solid or if they're a little loose.

As to removing the water, unfortunately your foam is never going to let all of it go. The foam isn't a solid block filling all of the space under the floor. There are voids and depressions that will trap some of it. The foam doesn't stay closed-cell forever, too. At this point try to suck as much out as you can. You could drill holes in the stringers but neither of these options will get all of it.

It sucks but it's rare to have an old Supra that doesn't eventually need new stringers. You could get years of use before you need to face that situation.

[covertcombatant]

I think I found the leak. I'm still guessing it was (is) the heater core up front. I think it was leaking and dripping into the carpet and gravity led it towards the foot rest tray area where the driver sits. The fiberglass under the tray wasn't 100 percent water tight and water went under the fiber glass and into the foam and I believe worked it's way back from there. I bought 4 feet of 5/8 heater hose and just bypassed the whole heater core.

I decided to run it like you said and threw the gas tank back in and all the interior. Getting on the lake tomorrow.

The temperature of the water was cold once it got back to the tray area after making its way through the carpet. Still guessing. I made a nice exploratory hole in the fiberglass under the foot rest area and found quite a bit of water. Thinking of pulling the whole foot rest area out and pulling all the foam but won't let that keep me off the lake and will do that in my free time.
Here is what my hole looked like today.