Water leak - 1995 Comp TS6M

We recently picked up a reasonably clean but needing some TLC 1995 Comp TS6M with ~400hrs on it. Part of the reason we were OK with the project was that research indicated that this rounded-windshield model had the composite stringers, so wasn't prone to the rot that took place on the earlier wooden stringer versions.

Boat has the PCM GT40 Pro Boss SEFI Ford 351W engine, which I'm quite familiar with.

Repairs performed so far:
- Blower replacement (one was seized)
- Throttle Position Sensor replacement to resolve surging issue
- Oil pressure sender replaced (gauge was jumping 0-40psi)
- Shifter linkage realignment
- Cable disassembly, cleaning, lubrication
- Packing for drive shaft replaced
- New stainless mufflers installed (original ones were rotten)

Current issues:
- Transmission fluid leak causing slip when it gets low
- Fuel level sender needs replacement, always shows full
- Engine temperature "limp mode" switch needs replacement, currently bypassed
- Heater hoses bypassed (assume the core leaks)
- Horn doesn't work
- Interior lights don't work
- Significant leak behind the drivers-side stringer that spills into the main bilge, significantly more when under way under load

This thread is about that last issue.

Reading through this forum and what I've found on google, it seems somewhat common for there to be leaks around the flaps on the rear of the boat. I was only up to the cottage for the weekend and when we pulled the large 3-man tube, we got significant accumulation (like to the floor) of water, which was made worse by an acorn shell fragment plugging up the bilge pump. Seems to be less of an issue with less load (just the boat, with people, no tube). It was originally taking in water around the driveshaft but that's been resolved and this "other" leak appears to be a bigger source.

Of significance: The water entering is quite warm, appearing to have come from the engine or having been in contact with the exhaust. This makes sense, given the compartment/location the water appears to be coming from.

One of the lag bolts for the right-rear motor mount is missing (there were several missing when we bought the boat, they've been all replaced except this one) and this is where significant water is coming through into the main bilge. Once the boat is settled into the slip and no longer being used, this leak turns into a drip. When you first get back and when you are under way it is quite the significant amount pouring through this hole. The bolts all bite into the stringers without issue, not sure why they were missing.

My current plant is to lift the boat in the slip with straps and see if I can see water coming out around the flaps or some other location. That failing, put some water into that area with a hose and see if I can make it leak.

Engine runs like a Swiss watch with the TPS replaced, and there are no visible leaks on or around it with it running.

Thoughts, feedback?

My first thought is the heater core. How was it bypassed? Almost sounds like could be leak in one of the hoses(supply or return). Warm to hot water while running makes me think this.

Quote:

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Originally Posted by NoWake

My first thought is the heater core. How was it bypassed? Almost sounds like could be leak in one of the hoses(supply or return). Warm to hot water while running makes me think this.

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This bypass was done by the previous owner or his/her mechanic. It appears they've taken a cut out of the longer section of hose that feeds the heater core and simply looped it from the hot water output on the side of the block back into the return on the bottom of the water pump.

Darn, cheapest fix would have been a new bypass hose. Next guess exhaust system. Muffler and/or exhaust hose leak? Hope you want to replace the carpet anyway as you might have to pull up part of the floor? Let us know how your leak test works. For that much water coming on board you might want a backup bilge pump in case the 23yr old one takes a dump.

Quote:

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Originally Posted by NoWake

Darn, cheapest fix would have been a new bypass hose. Next guess exhaust system. Muffler and/or exhaust hose leak? Hope you want to replace the carpet anyway as you might have to pull up part of the floor? Let us know how your leak test works. For that much water coming on board you might want a backup bilge pump in case the 23yr old one takes a dump.

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My guess is exhaust system as well. Doesn't appear to be any sort of leak at the coupling/muffler interface and the mufflers are brand new stainless ones. I'll double-check where it meets the pipe as it passes through the floor but my impression is that it is further along, probably near the rear of the boat.

And I hear you on the bilge pump, we ended up using a 2nd one "on a stick" to aide the original when it was plugged to get things dried out.

Out of curiosity, have you checked the underside of the rub rail along the sides and stern of your boat for gaps? I had an issue where I would get water in my hull and I could not figure out where it was all coming from, checked exhaust hose fittings, the through transom fittings and such, turned out I had water running into the boat along the rub rail at the aft three or four feet or so. As soon as I sealed that up the problem disappeared. It should be easy to check and address if necessary.

Quote:

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Originally Posted by Jetlink

Out of curiosity, have you checked the underside of the rub rail along the sides and stern of your boat for gaps? I had an issue where I would get water in my hull and I could not figure out where it was all coming from, checked exhaust hose fittings, the through transom fittings and such, turned out I had water running into the boat along the rub rail at the aft three or four feet or so. As soon as I sealed that up the problem disappeared. It should be easy to check and address if necessary.

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I ran my finger along a bit and it felt OK, but I haven't given it a solid look. I did that after I think I saw you mention it in another thread. My guess is that, since it still leaks while it sits stationary, albeit, not as much, that this isn't the primary source of the water if it is an issue.

Quote:

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Originally Posted by Jetlink

Out of curiosity, have you checked the underside of the rub rail along the sides and stern of your boat for gaps? I had an issue where I would get water in my hull and I could not figure out where it was all coming from, checked exhaust hose fittings, the through transom fittings and such, turned out I had water running into the boat along the rub rail at the aft three or four feet or so. As soon as I sealed that up the problem disappeared. It should be easy to check and address if necessary.

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So, I want to thank you formally here. I lifted the boat out of the water this past weekend to check the exhaust. There was zero leakage from the exhaust, even when I tipped the boat back. I also put a ton of water in the bilge to see if I could get it to come out, but none did. I snugged the clamps on the flaps, as they were a touch loose, but that's of no consequence.

With it in the air I got a good look at the under side of the rub rail. There was a significant gap on the right-hand side, and a bit of one on the left. It looks like it had been filled using cheap clear silicone and it had come out, and had separated away from the rub rail, some of it completely gone.

Hit up a local marina that actually had the nice white 3M Rub Rail sealant and adhesive and did about the last 4' of the boat and 1' around the back (the whole boat needs to be done, but this was the area I was concerned with) and took the kids out for a tube. Boat stayed dry! Didn't take on ANY water.

Also, worth noting, the front-most fin; the fin just below the tower, was extremely loose. I tightened it down as well as part of this. I assume this was my persistent leak when the boat was sitting. It appears to be staying dry now.

So, that problem is solved! I'm going to start a separate thread about the transmission, as that's our remaining issue with the boat.

Thanks again!