Fuel leaking from Breather

[CB77]

Hi,

I have just bought a 2003 Haines Signature 550c.

I towed it back to Brisbane from Taree when I got home I could smell fuel & noticed fuel running out of the breather down the transom.

The previous owner had filled the tank full before I picked it up and I thought the bouncing around on the shit Northern NSW roads had just pushed the fuel back through the breather.

Since Ive been home ive noticed the fuel again running out the breather again late in the afternoon while its stationary.

When I open the tank filler cap there is a fair bit of pressure released.

Does anyone know how to stop this occuring? a couple of people have suggested to lengthen the breather hose and put a large loop in it? or put a T piece in and add an extra breather in the transom?

Is this a common problem?

Any help would be appreciated.

[mik01]

is it sitting in the sun?

[Any_Weather]

Craig, mate I dont think this is really a concern as I suggest the tank is just overfull. If the breather outlets in the tank are covered in fuel, this will not allow gas to escape therefore pressurising the tank (this is why it leaks after expanding in the heat of the day) and blowing the fuel through the breather pipes which is its easiest escapre route. I would recommend draining a little bit of fuel if you can or use it as an excuse to take it for a run and use a bit. The only other reason would be insufficient breathers on the tank. Lets say there is only a breather on the port side and you park the boat on a slight angle and cover this breather the same thing will happen. I would think with the experience that signature boats have and the age of your boat this would not be the case.
This is only my interpretation of events that may be occurring but I may be incorrect.
Good luck
Lee

[CB77]

Yes I guess it could be just an over full tank & something I will have to monitor.

I have had other boats in the past and never had this problem.

Its not really in a full sun position & i dont think the days are hot enough at the moment to really cause a problem if so then it will pour out a lot more in summer.

Craig

[Roughasguts]

Lower the trailer at the front so the bum of the boat sticks up.
You will have more expansion room then and less likely to vent fuel.

Or drain a few gallons out.

[finding_time]

Craig

As Roughasguts alluded to your fuel tank probably only has a breather from one end( probably rear) so with an expanding air pocket at the front of the tank with the bow raised it will always have a tendancy to to blead fuel until the air pocket runs the whole length of the tank! A simple solution is to lower the bow but if the boat is out in the open , water will always collect in the bow . the other solution is more complicated , and involves getting a breather fitted at the front of the tank , pain in the @rse yes, but you'll end up with a better boat.

Ian

Ps. it will also make fill with fuel easier!

[BM]

Not uncommon for most boats to discharge fuel through the breather. Even one of my customers with a 34 Mustang when that is fueled it will vent a little bit of fuel.

[gofishin]

Craig,

ULP has a fairly high coefficient of cubical expansion, or the rate its volume/density changes with relation to temperature changes. Your problem is a combination of your tank being to full, and/or tank design, and/or attitude of the boat (tank) and the afternoon temperature.

In the afternoon the fuel will be at its hottest state - read largest volume. If there is insufficient space to accommodate this 'volume growth' above the liquid level in the tank, the tank will pressurise at the liquid escape height head (breather) from where fuel will come out the breathers.

The easiest fix is too remove some fuel, and not fill it up so much in the future. If your fuel filler cap is higher than you breather (at the attitude your boat is stored) you could try cracking this, but be aware that if your breather is blocked fuel could escape out thru the filler cap.

FYI...This is a common problem in Oz as there are no mandatory regulations governing tank design. From memory ABYC regulates a tank design fill level allowing 10% expansion, hence its physically impossible to overfill the tank.
cheers

[ozbee]

that's not a bad problem to have just thinking about the 500 dollars i have to spend to get mine to behave like yours................................$$$$$$$$$$$$$ $$$$$$$$

[CB77]

Hi,

I lifted the floor to check the tank, the breather outlet is at the front of the tank so I should lower the rear rather than the front which I have done.

The biggest concerns are the smell, fire hazard and Ive just noticed fuel in the bilge.

The fuel is running out the breather and back into the boat from the filler tube.

I guess I will have to seal between the hull and the filler tube.

[mik01]

Hi,

I lifted the floor to check the tank, the breather outlet is at the front of the tank so I should lower the rear rather than the front which I have done.

The biggest concerns are the smell, fire hazard and Ive just noticed fuel in the bilge.

The fuel is running out the breather and back into the boat from the filler tube.

I guess I will have to seal between the hull and the filler tube.

mate - I had a cracked O ring on my filler cap (underfloor tank) and leaked about 10L into the bilge when I had it parked downhill on the diveway!

it may freak you out a bit, but it's no big deal and won't catch fire unless you stupidly light up near it.

you should be able to jack up the jockey wheel, remove the bungs and put a bucket at the back under the bungholes and let it run out. i would then run a hose around the fuel tank and the bilge and flush it a bit more.

then just leave it to dry (bow cranked up high). the remaining fuel will evaporate and won't be a problem. as mentioned above, either don't fill it so high, or you could release the filler cap slightly so as to let gases escape and therefore reduce pressure buildup.

not sure if this will cause any other issues, but just remember to tighten it up when you head out!!

ps - my breather is at the front also, and you really should have the bow higher than the stern

[CB77]

thanks,

Thankfully I only had about 500ml fuel in the bilge so I just mopped it up and degreased it to get rid of fuel smell.

I spoke to northside marine yesterday & they also recomened to put the loop in the breather hose. last night I put the loop in & sealed the filller cap base where it meets the the hull, I guess i will find out soon enough if it worked.