Fuel leak repair

[Sneaks]

As you can see from the photos below, I have a mystery leak.

Apparently something is spraying fuel either when I'm in bumpy water or on the road. Unfortunately, it's dry as a bone sitting here at home. With the large number of owners here, somebody surely has seen this type of spray pattern before. My fear is, of course, making headlines while trying to isolate the leak with a full tank in choppy water. The stainless clamp seems tight but there's no real effective way to pressurize the tank.

Is there a product I can apply to the tank fill joint which will seal the area? My concern is the actual fill tube/tank interface which seems like the logical location if the fuel line itself isn't leaking.

Don

[rogerbum]

Are you sure that stain is from fuel and not just from the corrosion of the fittings caused by water?

[Sneaks]

Pretty sure. Looks like Stabil (which I use). Not like rust, not on the other tank, and smells like a petroleum product. Boat is 18 months new.

[Sea Wolf]

Don-

How far does that nipple extend up into the hose? Isn't stuff like this supposed to be double clamped on first class boats?

How much tension can you get on that clamp's screw head the way it's turned (toward the tank bulkhead)?

If the fitting with the exposed threads was cracked along a thread line, it would be next to impossible to see w/o tilting it sideways and adding a lot of magnification....note that the threaded area is "dirty" with the leaked material resideue, the top fitting clean........l


Could you "somewhat" seal off the tank vents, spray the affected area with soap solution (like they use for natural gas and propane) and gently pressurize the area with lots of low pressure air?

Joe.

[lloyds]

If I was to guess I would guess a hairline cracked fitting. Take the fittings all off and start over with new, and you should have a double clamp on the hose.

[Sea Wolf]

Unfortunately, the threaded fitting looks like it's molded into the tank during manufacture.

The fuel supply line works under negative pressure, so wouldn't spray. But it would leak fuel if the crack were large enough or when turning off the engine, fuel pump, and suction, in that order.

Is that lower fitting threaded both on the inside and outside? Might make for some pretty thin walls!

The hose and other fittings have quite a bit of leverage when magnified down on to the tank and final fitting.

What's the chance it's leaking AROUND the final fitting between it and the plastic tank?

Joe.

[Dora~Jean]

Don,

I agree with Joe, use soapy solution (or gas leak detector), try to seal off the vent(s) then gently use compressed air to provide positive tank pressure. Looks like a leak, my guess is the plastic tank to fitting interface -- not sure how to fix though? Keep us posted.

[thataway]

There should be a dip tube going almost to the bottom of the tank. The fule is sucked up--and any fuel which is spilt here is probably from around the tube, whiich is brazed into a nipple, interfaces with the plastic tank. Although pressurinzing the tank, may show where the leak is (no more than 1 to 2 PSI)--you will have to seal the vent and fill lines.

I would tend to clean and rough up this area slightly, Then put JB weld or other epoxy filler all around, including on the poly and lower part of the fitting. I suspect that with a good build up of epoxy it will solve the problem An underlying concern for me is also that there is a lot of leverage on this tube, and I wonder if there is enough flexability between where the fuel tube is fastened and the feed tube--ie a little "S" in the tubing for flexability.

[lloyds]

More I look at it, it looks like maybe a crack in the actual tank material. Motion would cause the pickup tube to wiggle, and/or the hose to wiggle which would allow fuel to slop up and leach out of a crack in the plastic around the fitting.

[Sneaks]

Update: Tuesday is "Sonny-do" day here, chauffeuring a Little Old Lady (the real "Jenny B") to her appointments etc., so not much got done in the way of troubleshooting. Did send the photos to C-Dory and Bret immediately responded. I have the old style 25 gallon tanks. He is sending me two new tanks (different manufacturer) to replace the old ones, under warranty.

Bret agrees with you Joe, and Steve as well. He's seen this pattern before and thinks the "plastic weld" (his term) between the metal tank fitting and the tank has cracked. With the tank near full, any surges from trailering or boating on choppy waters will spritz gas.

Bob, I don't think JB Weld will adhere to poly tanks too well, but your suggestion was right up there on my short list of repair solutions. In fact, while out with mom I picked up a fuel tank patch kit as well as some JB Weld and I'm going to try it anyway so I can burn off the fuel rather than transfer it

[Sneaks]

Another update:

I took some carburetor cleaner to the tank fitting and tank itself to clean up the fitting and the stains and prepping to put a temporary patch on. Definitely found the answer.

The early 25 gallon tanks have a brass threaded tube "plastic welded" into the tank itself. The inside is threaded as is the outside, and an aluminum "street L" is screwed into the end. A brass 3/8" barb is screwed into the street L and the fuel hose is clamped to the barb. You can see all that on the photo.

Whoever screwed the aluminum street L into my tank fitting must have overdone the torque because the brass is split vertically right down into the tank. Since I'm a cheap old phart, I had pulled the boat out of the water and really topped off with gas at the marine base gas station. First time the tank has been that full since new. I suspect vibration and tank surges just made the problem worse.

I don't know if the manufacturer supplies tanks complete with everything but the fuel hose or if C-Dory adds the fittings later, but it's a good thing to occasionally check your fittings.

Gonna try JB weld and now have an excuse to go burn off 20 gallons of fuel.

[westward]

I have had a similar leak situation which I discovered quite by accident. I had the original 75 gallon mono fuel tank replaced with twin poly tanks I thought to be 30 Gal. tanks. During my initial fueling with the new tanks, gas sprayed all over the place as I passed 24 gal. on the pump, mainly out of the vent hole. Once I (frantically) reduced the fuel level I noticed fuel still trickling out of the inlet/hose connection which I thought was due to undertightened clamps. Not the case. Further inspection revealed tiny pin holes in the tank itself, right near where the filler neck protrudes from the body of the tank. Both tanks turned out to have the holes. The factory unhesitatingly replaced the tanks, but the replacements also had the pin holes. Apparently there was an ongoing QC problem with the fuel tank vendor. This is a very long winded way of suggesting you check the tank itself, particularly near the base of the filler neck, for small pinholes which were a manufacturer's defect for a time. The factory's support in my case was excellent. Good luck. Mike.

[Byrdman]

Bad to know there is this issue....good to know we are getting quick factory response. I would like to see some answers to Don's questions as to who does what parts of the assembly process. what are the brand of tanks going into the C-Dory boats? Or... I guess they could change vendors as they wish. Interesting read.

Guess it would be a good time to stur up that old thread on who smokes and allows smokers on their C-Dory boats... Na... just kidding.

[Sneaks]

Update as of 6/12 Received new Moeller tanks from the mothership and after emptying the tanks, pulled them for replacement.

Surprise surprise, the new tanks are 2 1/2" wider than the old, but fortunately only the side hold downs had to be re-positioned along with my fuel filter, though I also moved the Starboard brand shields inboard by 2.5" and repositioned the strap holder at the same time.

Not so surprising, a close examination of the old tanks showed split brass fittings on both the fuel and vent fittings due to neanderthal torquing. No wonder the factory switched manufacturers.

Two tips and a conclusion:

The tanks are a fairly loose fit. Make sure there is a little clearance between the hold-in strips and the tanks then only loosely tighten the strap before initial fill and if you can, let it sit for a day or two before cinching the strap down tight so most of the "swelling" is done.

Don't bother to disconnect the fill and vent lines until the tank is loose and can be lifted over the side hold down and tilted partially. MUCH easier to manipulate the hoses and slide them loose. Same for reinstalling.

The Moeller tanks are definitely higher quality.

This is for 2005 and earlier C-dorys that do not have the new fiberglass hold-in strips, by the way.



Don

[Sealife]

On my old Sealife, I upgraded to the newer style tanks from the factory, installing them myself. Oncel installed I filled each tank with 5 gallons of fuel. That's when the fun started. I noticed fuel dripping out of my stern drain tube...panic!! Put a bucket under it and frantically started siphoning out the gas from the leaking tank. After removing the restraining panel and strap, I saw a pinhold at the point of one corner leaking gas. Got all the gas out and the tank removed without blowing myself up, but then discovered gas still running out of the boat. The other tank also had a similar pinhole. Now I'm exhausted and faced with another tank to empty and remove, without blowing myself up. Got it done safely, called the factory, and they sent me out two new tanks. I think what had happened was in shipping. The factory had re-boxed the tanks for shipping, and it looked like they were dropped on their corner, and a box staple may have punctured them. Since then, they have changed suppliers. The new tanks, supplied with my new boat, are a bit more rigid.