pagoda
Well-Known Member
Cautionary tale of pipework.
I got a stronger than normal whiff of diesel recently, and found about a litre (?) in the bilge. Not the below engine bilge, but midship adjacent to the chart table/diesel tank area.
This was after a fairly strenuous North Sea crossing to Norway, so my initial thought was cracked tank or loose fitting?
Looking at the base of the tank it was dry, as were visible fittings and the tap. Nothing dripping from behind the tank out of sight either.
I took up the cabin sole boards to investigate further, and found the diesel had come from under the chart table foot rest. That is not very accessible, as though partly screw and panel pinned, it's been assembled as a box and the seams glassed before mounting. All good and solid, but an utter pain to investigate/dismantle (1988 Jeanneau Sunrise- mostly traditional GRP work, all the internal furniture seams are glassed over out of sight.)
Chisels and a thin sawblade got me access, and I pulled off the offending panel.
Out of sight (and truly inaccessible!!) one of the two copper fuel pipes was weeping ever so slightly. With a bit of checking I discovered it was the diesel return line.
The way it was routed, it had little clearance between the inside of the hull and a protruding part of the chart table furniture frame. Glass is harder than copper, and I suspect the recent rough passage had just accelerated the wear rate. Ergo pinhole forming.
The main diesel feed line has a tap, which is great - but useless in this case.
The return line does not have a shut off tap. SO had the leak got any worse, I could not have prevented the entire tank emptying into the bilge!
I crimped the line shut and sawed off the offending short section. The temporary fix is a bridge of thick walled fuel quality hose, well padded and away from sharp edges. I have also put in a small fuel non-return valve as a precaution against any further similar problem. The return line goes into the tank at the same level as the outlet, so there is enough head in the tank to keep the NRV shut. It takes virtually no effort to make the valve pass the other way (easy to blow through prior to mounting it). It's now sorted at the moment. I will replace the lot with Kunifer tube when I get the chance. It's less easy to work than copper, but much tougher. The wood panel hiding the scene of the incident is back, but with some screws rather than pins and glue.
So gents, I suggest you go and have a look at your fuel tanks, and think about what would happen if you had a return line leak somewhere out of sight?
And what you might do about it? (next winter?). How much of your fuel lines can you see? Are they still good?
I got a stronger than normal whiff of diesel recently, and found about a litre (?) in the bilge. Not the below engine bilge, but midship adjacent to the chart table/diesel tank area.
This was after a fairly strenuous North Sea crossing to Norway, so my initial thought was cracked tank or loose fitting?
Looking at the base of the tank it was dry, as were visible fittings and the tap. Nothing dripping from behind the tank out of sight either.
I took up the cabin sole boards to investigate further, and found the diesel had come from under the chart table foot rest. That is not very accessible, as though partly screw and panel pinned, it's been assembled as a box and the seams glassed before mounting. All good and solid, but an utter pain to investigate/dismantle (1988 Jeanneau Sunrise- mostly traditional GRP work, all the internal furniture seams are glassed over out of sight.)
Chisels and a thin sawblade got me access, and I pulled off the offending panel.
Out of sight (and truly inaccessible!!) one of the two copper fuel pipes was weeping ever so slightly. With a bit of checking I discovered it was the diesel return line.
The way it was routed, it had little clearance between the inside of the hull and a protruding part of the chart table furniture frame. Glass is harder than copper, and I suspect the recent rough passage had just accelerated the wear rate. Ergo pinhole forming.
The main diesel feed line has a tap, which is great - but useless in this case.
The return line does not have a shut off tap. SO had the leak got any worse, I could not have prevented the entire tank emptying into the bilge!
I crimped the line shut and sawed off the offending short section. The temporary fix is a bridge of thick walled fuel quality hose, well padded and away from sharp edges. I have also put in a small fuel non-return valve as a precaution against any further similar problem. The return line goes into the tank at the same level as the outlet, so there is enough head in the tank to keep the NRV shut. It takes virtually no effort to make the valve pass the other way (easy to blow through prior to mounting it). It's now sorted at the moment. I will replace the lot with Kunifer tube when I get the chance. It's less easy to work than copper, but much tougher. The wood panel hiding the scene of the incident is back, but with some screws rather than pins and glue.
So gents, I suggest you go and have a look at your fuel tanks, and think about what would happen if you had a return line leak somewhere out of sight?
And what you might do about it? (next winter?). How much of your fuel lines can you see? Are they still good?
