Diesel Fuel

[CoastalLiving]

Hi,
We filled our tank up to the very top, but now I'm reading that with an increase in temperature, fuel expands and you are not supposed to fill your tanks to the tip top. I now have a fuel smell. Could it be that we filled it up too much?
Thanks,
Isabel

[Capt.Alex]

Diesel does not expand much with temperature. You may get a little bit leaking from the fuel tank vent on the side of the hull. You may also want to look at the top of the tank. There are sealed openings on the top of the tank where the fuel gauge sending unit is installed or other access plates that have gaskets sealing them. If the gaskets are leaking, then a topped off tank could leak some fuel into the bilges until all of the fuel in the fill pipe has leaked out back down to the level of the top of the tank. Take the opportunity to track down any leaks, then fix them!

[djmarchand]

Diesel fuel expands about .0005 per degree F. So if the temperature of the marina's fuel tank were 20 degrees lower (possible because it is probably buried) than your fuel tank after it all comes to equilibrium over a few days, then the diesel will expand 20*.0005 = .01 or 1%. So it could overflow out the vent and that is why you are smelling something.

Also rough water could bounce the fuel level around and force some out of the vent.

David

[boatpoker]

Don't forget that the return line is sending hot fuel back into your tank from the engine and in my experience that additional heat and frothing will send fuel out your tank vent if the tank is full.

[CoastalLiving]

Thank you for this feedback. A challenge that I am running into because of the boats age, it is all a little oily. I think I need to clean all of the fittings, etc. first and then continue to hunt down the leak. I looked in the bilge and there is a little bit of residue, but nothing crazy. So maybe filling it to the top was not the best idea!!! I will continue to work on solving this quandry:-)
Isabel

[CoastalLiving]

Well, it is the fuel tank. We checked everything else and there is fuel in the bilge. We have a Catalina sailboat. Besides Catalina Direct, does anyone else know of any sites to look for new tank?
Thanks,
Isabel

[klmmicro]

Made a mistake and filled my tank to the brim ONCE...fuel odor from vent for about a 1/4 tank. Once the tank hit 75 percent, it seemed to subside.

Might check your fuel lines where they go through any sort or deck/rib hole. I have a new aluminum tank that I purchased local to me. Will hunt down the manufacturer's name for you when I am aboard in a couple of days.

[belizesailor]

Originally Posted by CoastalLiving

Well, it is the fuel tank. We checked everything else and there is fuel in the bilge. We have a Catalina sailboat. Besides Catalina Direct, does anyone else know of any sites to look for new tank?
Thanks,
Isabel

Tank itself is leaking? Not just a fitting or hose? How old is the tank?

Check fuel lines to/from the engine as well. I unknowingly damaged a line recently while doing other work and discovered a bilge full of diesel next AM.