Fresh water leak – NT32

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    We purchased a 2000 32 in May.  Bilge was dry.  Now we have fresh water in the bilge under the engine.  The aft bilge is dry. The leak increases when motoring in rough conditions that are common in the run from Blaine to the San Juans. I have been unable to locate the source of the leak. Several gallons will accumulate during a five day cruise.  Any suggestions?

    Tom EasterbrookTom Easterbrook

    If the water is freshwater it must be coming from your freshwater system, or water runoff from the rain, boat washing, etc.

    There are 2 possible sources from the boat’s freshwater system that come to my mind. First, is the pressure relief valve on the hot water tank. Mine often vents some water (small amount) into the bilge (near the tank NOT under my engine) when heated, especially heated by the engine’s coolant (very hot, about 180 degrees F). The second source, is a bit harder to locate, as it could be from your freshwater plumbing. There are many joints and/or connections in the system, and any one (or more) of them could be leaking or a pipe could be cracked. Does your pump cycle on and off when there is no apparent demand for freshwater? If so, your water system has a leak somewhere.  Several gallons over 5 days seems like a fair bit. My water heater will put a cup or 2 in the bilge, not gallons.

    Likely locations for outside water leaks include the stanchion posts, cleats, deck penetrations, etc that may need rebedded.

    Good luck,


    • This reply was modified 1 month, 1 week ago by Tom EasterbrookTom Easterbrook. Reason: typo
    Doug FordDoug Ford

    There are not many fresh water sources around the engine so I wonder if it could be raw water?? The raw water pump on the 6BTA is problematic and hard to access, but I’d check it for leaks. Otherwise, follow the raw water route and examine hoses all the way to the exhaust elbow. Feel all around the elbow also for corrosion; they can fail and leak. All my advice assumes it is raw water so if you’ve determined it is fresh, then I really don’t know.

    Tom EasterbrookTom Easterbrook

    Unless I am losing my mind, I think I answered this earlier, but don’t see the response anymore.

    Anyway, if you are sure it is freshwater (follow Doug’s advice if it is salt),there are only really 2 sources, the freshwater plumbing or an external leak allowing rain water in. Internal options are the water heater pressure relief valve (mine sometimes let out a small amount of water – not gallons), a water tank leak, or (harder to find) a leak in the piping/fixtures somewhere.

    External sources could be very hard to trace and could include leaks around any deck penetrations like stanchions, cleats, railings, windows, portholes, etc., or leaks at the hull to deck joint, rub rail attachment, etc. , but here, I would expect it to be more saltwater based.

    Another comment following up on Doug’s advice is regarding the exhaust elbow. The original Cummins elbow that has the cooling water enter right up at (near) the turbo can turn out to be a real problem when they develop internal leaks. This will happen sooner or later. When mine did, I would not have known there was a problem except for the exhaust hose overheat alarm I had installed. All other temperatures looked good, and there were no visible signs of ANY leaking. The alarm sounded alerting me to high exhaust hose temperatures, hot enough that the hose could have been “cooked” if I had not caught it. Worse, the leaking saltwater could have entered my turbo (expensive) or worse yet entered back into my exhaust manifold and engine causing major problems (very, very expensive).  If your elbow does not have a heat blanket, then I strongly suggest checking your exhaust elbow this off season and replacing it with a custom made one (about the same price as the original) to address this potentially big issue. I can recommend National Marine Exhaust out of Marysville, as they made mine.


    Since I first posted, I’ve added green food coloring to the fresh water tank. The water in the bilge is now green. I think the source of the leak is the outlet hose on the starboard tank.  Of course it is hard to access.

    At least, I the leak isn’t from the raw water pump or the mixing elbow.  But I want to change the elbow, so greatly appreciate your advise and source for a new part.  The raw water is a beast to remove.  Any magical tricks to unbolting it?  Thanks.

    Tom EasterbrookTom Easterbrook

    I will try to answer again. I seem to be experiencing problems with disappearing posts on this site, but not on any other forums??

    Soak the bolts using something like PB Blaster. Spray some on and leave it for a few hours or overnight. Do this a few times. If then they are still too tight, you might try a bit of heat like a torch, or hiring a pro (mechanic) to remove. This is for the elbow.

    For the raw water pump, you will probably need to “jack up” the forward port corner of the engine (if your pump is located in the same location as mine) to just take the weight off the engine mount there. Temporarily remove the mount to gain better access to the lower pump mounting bolt. If rusted, PB Blaster may help. I am trying to attach a photo of my “new exhaust” to give an idea of the concept.

    Good luck.

    Exhaust Elbow

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