Fresh water leak 390 EC

Bull53

Bull53

New Member
Jan 11, 2018
11
Clear Lake, Texas
Boat Info
1989 390 Express Cruiser
Engines
Mercruiser 454
I have discovered fresh water in the storage bins in my salon and galley floors in my 1989 390 EC. My fresh water tank is showing at least 2/3rds full and I am also connected to fresh water supply at my slip. I need advise on how to approach finding what is leaking and especially how to access the fresh water tank without cutting into the sole. Any experience out there?
 
I'd start by immediately disconnecting the shore water. Then dry everything out and see if the problem recurs. Place paper towels under every water connection you have access to, and monitor closely.

If the problem recurs its prolly coming from the fresh water tank.

Also watch your usage patterns. Do you shower often on the boat. Use the galley sink more than the head sink? This may yield a clue. Does the problem occur only after filling the fresh water tank? I had an issue where I got water in the bilge every time I filled the tank. The tank had a 4" inspection port on top which would leak once water reached the top of the tank.

Is your slip covered? If not has it been raining or snowing? Any water leaking in from the outside will eventually make its way to the lowest point. Strategic placement of paper towels is as called for here as well.

Not sure where the tank is located on yours, It's somewhat easy to access on mine by removing the cushions in the mid-cabin.

never leave the slip water connected when you are not at the boat. Having an endless supply of water attached to your boat with no-one around to monitor is a really bad idea.
 
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When you say storage bins which do you mean as there are 3. Then long narrow one in the galley area usually has the vacuum cleaner hose and attachments. The other 2 are one the center line of the boat but sit higher than the water tank when the boat is in the water so a leaking water tank shouldn't cause water in any of the in floor storage compartment other the water tank compartment itself. So therefore water in the in floor compartments can come from the shower sump leaking/overflowing, the shower or sink drain hoses or even the anchor locker in the locker drain hole is clogged. Another possible source is the side windows that can leak around the edges or where the window panes are fitted to the frames. BTW the only water tank access is in the rear under stairs by removing the risers. Removing the tank requires cutting out and removing a sizable section of the cabin sole.
 
Thanks. All good advise. Tank is centered under salon sole between salon sole storage bin and the engine room bulkhead. Hoping to hear from other 390 owners if there is way to inspect.
 
Bull53 said:
I have discovered fresh water in the storage bins in my salon and galley floors in my 1989 390 EC. My fresh water tank is showing at least 2/3rds full and I am also connected to fresh water supply at my slip. I need advise on how to approach finding what is leaking and especially how to access the fresh water tank without cutting into the sole. Any experience out there?
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Bull53 said:
I have discovered fresh water in the storage bins in my salon and galley floors in my 1989 390 EC. My fresh water tank is showing at least 2/3rds full and I am also connected to fresh water supply at my slip. I need advise on how to approach finding what is leaking and especially how to access the fresh water tank without cutting into the sole. Any experience out there?
Click to expand...
This seems to be a common problem in the 390EC and in various years i have friends with the 1985 ,1986 ,1987 ,and 1988 models all having the same problem. In one of the 85's we cut the floor removed the tank Then had a new one made and replaced it. Checked all connections, hoses and water lines. "WE TOOK CARE OF THAT PROBLEM" NOPE! Some time later water showed up again. So it's not the water tank
 
Thanks hottoddie I knew the pump was under stairs but didn’t think about accessing tank area there.
 
Thanks 390 Express. I intend to check hoses and connections first (start with the easiest solution). Have heard all about replacing the tank and don’t wanna go there.
 
The 100 gal. aluminum FW tanks on these boats were natorious for developing pin holes in the bottom of them. There is no magic solution ... you need to change out your tank.
 
Wet vac storage area. There is a board covering front portion of tank, remove it. Continue to vac. Take a flashlight and peer alongside water tank. You should shortly see water seepage alongside the tank. Hurry and replace that 30 yr old tank. Summer is almost here...
 
I owned a 390 ec for ten years,, been in same situation.

do what Jeepers said above, and also what hotoddie said about removing the steps and the risers so you can look down behind the tank and dry out that area.(it will be lowest part of that compartment thus water usually appears there first.)

from there you can also see the vent and fill hose.
 
Years ago, I took my FW tank to a local "Line-X" dealer who was also a fellow boater. He dipped my tank in an acid etching solution, welded up my pinholes, prime painted the tank and double coated the bottom and sides with their truck bed liner coating. He had done this with his own water tank several years before with success so I did the same. I layed 1" wide rubber spacers every 12" across the underside of the tank to keep it up off the floor and 10 years later it is still going strong.
 
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electricaldoctor said:
Years ago, I took my FW tank to a local "Line-X" dealer who was also a fellow boater. He dipped my tank in an acid etching solution, welded up my pinholes, prime painted the tank and double coated the bottom and sides with their truck bed liner coating. He had done this with his own water tank several years before with success so I did the same. I layed 1" wide rubber spacers every 12" across the underside of the tank to keep it up off the floor and 10 years later it is still going strong.
Click to expand...
 
There is no short cut. I removed the carpet and cut open the plywood floor. I also had to remove the fridge and stairs. When I removed the fridge, I noticed that the fridge was draining directly on the floor, so I ran a 1/2" Pex pipe back to the shower sump pump box while the floor was open and the tank was removed.
 
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