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Fuel leaking from return pipe connection


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You can easily repair the cracked flare nut by removing ,gripping in a vice and putting a bead of weld on the crack.............without seeing it apart,its possible  threads are mismatched,and the nut has cracked from being forced onto the wrong thread.......Another difficulty I see ,is the fitting appears to be welded/brazed into the tank.....so if the threads on that fitting are wrecked,its a fair job to fix it.

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OK, got more info, hope its useful!

 

The thread out of the tank appears to be ~14mm

the fuel pipe measures 7.9mm so assume 8mm?

 

the other fuel feed to the tank has what seems to be a 1/4 ball valve but that doesn't seem to equate to 14mm?   the screw threads out of the tank for both seem to be the same.  does this help??

i can take photos etc if this makes things clearer - thanks for the help to date!

20220614_075545.jpg

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Thread on the tank is 1/4" BSP Male.

Union is 5/16" compression.

 

So you need a 5/16" compression union to 1/4" BSP FEMALE  fitting.

 

Some pipe sealant suitable for diesel, like Hylomar Blue on the male thread will seal it. Do Not overtighten else you will split it again, the thread is tapered.

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one last point then i'll leave this as i have to use up the fuel before i can do anything.... excuse for a cruise?

 

if i want to fit a ball valve is there a certain type?  keen to keep in with any safety etc.. ones i've seen are gas/hydraulic?

 

rob

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As a side note, got to love the desperation of swinging on that joint in an effort to stop the leak to the extent of splitting the fitting!

Never going to work.

This was a GAS pipe joint in my gas locker to a bulkhead connector. Desperate pipe crushers R us Tut-tut. I wonder how many times that was nipped up a bit.

IMG_20160706_145655228.jpg.32066f10a8f83aca3b1dc55aa2d69dc9.jpg

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36 minutes ago, robtheplod said:

one last point then i'll leave this as i have to use up the fuel before i can do anything.... excuse for a cruise?

 

if i want to fit a ball valve is there a certain type?  keen to keep in with any safety etc.. ones i've seen are gas/hydraulic?

 

rob

I looked for one suitable for oil, diesel etc but i’m Sure the gas ones are the same. To be safe i would go for a full not reduced bore valve as i’ve Been told restrictions in the return line can cause problems

if you fit it in line a 8mm pipe slicer is handy. When you tighten the nuts hand tight + one full turn 

when you remake tank compression fitting you could use ptfe tape or sealant the flow is going  back to the tank not to the injectors

 

good luck I had to use up 6” fuel to drop  the level. In my boat that is around 50 litres or 50 hours.

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6 hours ago, Steve56 said:

Definitely imperial as indicated with the shoulder at the top. Metric fittings have the shoulder at the bottom. On odd occasions some of the manufacturers nowadays don't seem to bother with this. The pipe in the photo is probably 5/16. Don't mix and match metric and imperial fittings, it's just a bodge and is asking for problems further down the line. I would say the problem you have is that the pipe coming from the tank has a tapered thread and your fitting has a parallel thread. Obviously been forced on and caused the split. As someone else has already mentioned you should really have a ball valve fitted in the return line.

Screenshot_20220614-084326_Chrome.jpg

Screenshot_20220614-084403_Google.jpg

 

Thanks, I didn't know that, thats useful info.  I suspect this is true of proper wade fittings (plus the thread info that I mentioned earlier) but if you get cheapo fittings of eBay then nothing is certain.

 

I suspect that putting a female union onto a steel male taper is asking for splitting failures so fitting a steel stop valve would have another advantage.

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7 hours ago, john.k said:

You can easily repair the cracked flare nut by removing ,gripping in a vice and putting a bead of weld on the crack.............without seeing it apart,its possible  threads are mismatched,and the nut has cracked from being forced onto the wrong thread.......Another difficulty I see ,is the fitting appears to be welded/brazed into the tank.....so if the threads on that fitting are wrecked,its a fair job to fix it.

 

It looks like brass to me 😀,

Even if it was steel welding small components can often compromise the thread, and then forcing it on might damage the thread in the welded on bit.

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The ball valve needs to be advertised as suitable for diesel.  The particular bit affected is the seal between the ball that rotates  and the main body of the valve.  It is usually some sort of plastic and if it does not suit diesel it either swells, seizing the valve, or dissolves, meaning no shut off.

 If you cannot find one on line,  a central heating plumbers merchant should be able to find you one suitable for a central heating oil tank.

 

Do not use ordinary  PTFE tape to seal diesel.  The diesel slowly destroys it and it will start to leak.  Blue Hylomar is OK, Heldite is good, so is the blue stuff Screwfix sell.

 

If the tank stub threads are rough, or weld-spattered look out for a thread file.  These are designed for repairing damaged threads- you will need one for the correct number of tpi for a 1/4 BSP thread.

 

Alternatively look for a 1/4 BSP die nut.  Tracy Tools or the Tap and Die Co.  You will not need a HSS one- carbon steel will do.

 

You may even get away with cutting 3 or 4 hacksaw slots in a suitable threaded steel or malleable coupling and working it on gently with plenty of oil.

 

N

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55 minutes ago, BEngo said:

The ball valve needs to be advertised as suitable for diesel.  The particular bit affected is the seal between the ball that rotates  and the main body of the valve.  It is usually some sort of plastic and if it does not suit diesel it either swells, seizing the valve, or dissolves, meaning no shut off.

 If you cannot find one on line,  a central heating plumbers merchant should be able to find you one suitable for a central heating oil tank.

 

Do not use ordinary  PTFE tape to seal diesel.  The diesel slowly destroys it and it will start to leak.  Blue Hylomar is OK, Heldite is good, so is the blue stuff Screwfix sell.

 

If the tank stub threads are rough, or weld-spattered look out for a thread file.  These are designed for repairing damaged threads- you will need one for the correct number of tpi for a 1/4 BSP thread.

 

Alternatively look for a 1/4 BSP die nut.  Tracy Tools or the Tap and Die Co.  You will not need a HSS one- carbon steel will do.

 

You may even get away with cutting 3 or 4 hacksaw slots in a suitable threaded steel or malleable coupling and working it on gently with plenty of oil.

 

N

Brass Ball Valve 1/4" BSP Female Each End (Lever Handle) (asap-supplies.com)

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11 hours ago, Steve56 said:

Definitely imperial as indicated with the shoulder at the top. Metric fittings have the shoulder at the bottom

Many decades behind me and still learning new things.

Never knew that.

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3 minutes ago, reg said:

Many decades behind me and still learning new things.

Never knew that.

I've spent my whole life as a marine engineer. I certainly wouldn't claim to know it all. You can always learn something new, or a different way to go about things. If someone claims to know it all there probably best avoided.

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Posted (edited)

Thanks to everyone who's given advice on this!

 

I'm ordering bits and so far have:

  • 1/4" BSP Female (both ends) ball valve (full flow) - rated for oil/water/gas
  • HYLOMAR Universal Blue non-setting Instant Gasket Jointing Compound Sealant 40g

Got both the below so i can be sure one will fit. As I understand it i test the screw thread to be 100% sure which to use:

  • 8mm COPPER COMPRESSION FITTING to 1/4" BSP MALE
  • 5/16" COPPER COMPRESSION FITTING to 1/4" BSP MALE 

as the compression fittings come with olives I'm guessing I don't need to look into any sort of 'flaring' tool for the ends? - just like working on standard miniature copper piping?  I've got a pipe cutter.....  Do I apply the HYLOMAR liberally or just a smidge?

 

I've got the diesel level down below the fitting now so its no longer dripping which is great. I've now got a Jerry can full of dodgy diesel as I've taken it from the bottom using my heath robinson siphon pipe! (looks mainly small rust flakes) so now need to polish that up!

 

thanks!

Edited by robtheplod
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No need for flaring the copper pipe. It's like 15mm copper, but smaller😊.   Do ensure the pipe is fully into the fitting before you compress the olive, and do not over tighten. Hand tight plus half a turn.  For the pipe to ball valve fitting, choose the one with the olive that is the best fit on your pipe.  Either are likely to be quite OK as there is bugger all in it between 8mm and 5/16 in. Just less than 2.5 thousands of an inch.

 

If you need to bend any existing copper pipe, anneal it where you want to  bend first.  Get it just red hot (so you can barely see red in a dim light)  and allow to cool. A DIY shed canister  blowlamp will do the job, so will a gas ring. New copper pipe is likely to be OK to use.

 

 

 Apply sufficient Hylomar to fill the threads on the male component, only.  Wait 5 minutes for the solvent to evaporate and the surface to become less sticky.  Fit the female part.  Do not over tighten onto a taper thread male fitting as you are likely to split the female, especially if it's a brass female thread.  

Do not apply Hylomar to olives or compression fittings.  They do not need it and if is usually a bodge to cover up an over tightened fitting.àq

 

Either cellulose thinners or meths will remove surplus Hylomar.

 

N

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6 minutes ago, BEngo said:

No need for flaring the copper pipe. It's like 15mm copper, but smaller😊.   Do ensure the pipe is fully into the fitting before you compress the olive, and do not over tighten. Hand tight plus half a turn.  For the pipe to ball valve fitting, choose the one with the olive that is the best fit on your pipe.  Either are likely to be quite OK as there is bugger all in it between 8mm and 5/16 in. Just less than 2.5 thousands of an inch.

 

If you need to bend any existing copper pipe, anneal it where you want to  bend first.  Get it just red hot (so you can barely see red in a dim light)  and allow to cool. A DIY shed canister  blowlamp will do the job, so will a gas ring. New copper pipe is likely to be OK to use.

 

 

 Apply sufficient Hylomar to fill the threads on the male component, only.  Wait 5 minutes for the solvent to evaporate and the surface to become less sticky.  Fit the female part.  Do not over tighten onto a taper thread male fitting as you are likely to split the female, especially if it's a brass female thread.  

Do not apply Hylomar to olives or compression fittings.  They do not need it and if is usually a bodge to cover up an over tightened fitting.àq

 

Either cellulose thinners or meths will remove surplus Hylomar.

 

N

All excellent advice. I put a felt tip mark on a flat so I can see how many flats i’m giving it as I tend to lose count in the heat of the moment!

 

good luck it sounds like you are getting all your ducks in a row. 

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1 hour ago, robtheplod said:

The pressure is on, if i mess this up then i can't show my face around these parts again!  :)

I’m still on and i’ve had my share of o shit moments. It definitely pays to give the job a good “coat of looking over” before wielding the spanner in my case!

i had a stem gland leak a couple of weeks ago which was cured thanks to Tracy for suggesting checking the engine alignment which had never occurred to me despite it being obvious. 

In amongst it all  you can get a lot of sound, helpful advice from people that know.

i’ve not admitted to a weedhatch leak as well yet which took me a week to identify.....

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Posted (edited)

Hi All, visited today and was able to sort with all the parts and all the great help you gave.... all connections are fine although my compression joint leaks ever-so slightly.. happy to give it some time to see if this resolves or i need to redo - don't want to over tighten!

 

thanks for everyone who helped me!!!!

 

rob

 

 

20220625_095213.jpg

Edited by robtheplod
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I can see  nothing immediately wrong  in your picture but the compression joint is not likely to stop weeping without you doing something.  Undo and lift  the nut without moving the pipe.   Look at the olive.  There should be a uniform, very tiny parallel gap between the olive and the fixed part of the fitting. The pipe should not be crushed by the olive.  If the pipe is off line the olive will struggle to seal and the gap will not be parallel.

  There is a pic of a badly crushed pipe/olive up thread a bit. If not as it should be you will need to redo, but a short term bodge is to give the olive and the pipe either side a dollop of Hylomar and fasten it all up again.

Clean any excess Hylomar off the outside, so the bodge is not obvious!

 

If it is OK reassemble as now, then tighten the nut, one flat at a time checking to see qq the leak stops.  Do not exceed a total of one full turn from hand tight.

N

 

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7 minutes ago, BEngo said:

qq

Typo?

Or something else I don't know?

 

Good info by the way. I'm never sure how tight to make a joint so I probably err on the side of over tightening.

Edited by reg
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