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Lister SL3 fuel leak


SweetPromise

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Hoping someone might be able to shed some light on a fuel leak we have. 

 

When we bought the boat, we didn't have any leaks at all. Then the mechanic came and replaced the diesel filter and the leaks began. It started with a leak from the filter to the pump, then he changed the brittle rubber hose that was connecting the filter to the pump with a copper pipe, and a new leak appeared from the pipe to the pump. Now there's three leaks, both the entry and exit points from the pump and the exit point from the filter. We had to leave the area where we were so the mechanic never came back to sort it out. 

 

We've tried tightening the nuts a bit but it hasn't helped. Does anyone have any ideas please? When we cruise, diesel spurts out all over the wall and it's leaking into the sump constantly. Someone has mentioned olives, could it be to do with them? 

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IF he tried to tight the adapter into the filter head or the lift pump body then they look tapered so he may have split the aluminum bosses.

 

If the lift pump can be fed by gravity then make sure the rubber seal under the lift pump cap and the soft washer around the center bolt is not leaking.

 

I think all the pipes are sealed to the adapter by olive and the one on the filter head and one of the lift pump ones look as if the olives may have been crushed. I don't understand why a proper olive seal needs PTFE tape. It looks like a bit of bodging has been going on. It might be a good idea to inspect the olives.

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I agree overtightening is likely to damage a casting or strip a thread.  Especially as that is the area where work was recently attempted.

However, I'm also puzzled how diesel is finding its way into the sump!?  That would suggest another issue where the feedline attaches to the rail that feeds the injector pumps.  This would be a major issue as diesel diluting the lubrication oil is to be avoided at all costs.

 

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If the threads in the pump or filter are only damaged a suitable plug tap will clean them up.  They may  be 1/2 x20 tpi UNF, BUT  CHECK, against the thread on the fittings.  Seal the fitting in with Tru Blu from toolstation, or Heldite, which looks like it has already been used.  Tracy Tools are good suppliers for taps.

 

If the pump or filter is cracked, then the body at least will need to be replaced.

 

I would try to source three new fittings with new brass olives.  If the pipe has been crushed where the olives fit then you will also need to start again with an un-crushed pipe. 

 

N

.

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42 minutes ago, BEngo said:

If the threads in the pump or filter are only damaged a suitable plug tap will clean them up.  They may  be 1/2 x20 tpi UNF, BUT  CHECK, against the thread on the fittings.  Seal the fitting in with Tru Blu from toolstation, or Heldite, which looks like it has already been used.  Tracy Tools are good suppliers for taps.

 

If the pump or filter is cracked, then the body at least will need to be replaced.

 

I would try to source three new fittings with new brass olives.  If the pipe has been crushed where the olives fit then you will also need to start again with an un-crushed pipe. 

 

N

.

On soft copper pipe such as this, then copper olives are the thing to get a good seal, preferably with inserts to avoid crushing the pipe.

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4 hours ago, Ex Brummie said:

On soft copper pipe such as this, then copper olives are the thing to get a good seal, preferably with inserts to avoid crushing the pipe.

Disagree.  On soft copper pipe brass olives are much harder so reduce the likelihood of crushing the pipe.  I have never seen an insert for copper pipe.

 

On half-hard pipe, then copper olives are fine, because the stiffer pipe resists crushing better than soft pipe.

 

In the OP's case, I suspect the original pipework involved brazed ferrules and  sleeve nuts, but these are not as easy to come by as once they might have been.

 

 

N

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Thanks for all the input. Sounds like I could try a few things out.

 

5 hours ago, Steve56 said:

Interesting that he has a mix and match of imperial and metric fittings, or it certainly looks that way. I know people try to do this but it is bad practice and never really successful.

Funny you mention this, the mechanic did say something about this and didn't have the right spanners for the job as a result. The whole engine seems to have been a bit of a bodge job here an there. The mechanic found a tin can being used between the exhaust pipe and silencer, and a hessian bag as lagging for the exhaust pipe. So I'm sure there's still lots of fun things to discover...

 

 

11 hours ago, BEngo said:

 

 

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2 minutes ago, SweetPromise said:

Funny you mention this, the mechanic did say something about this and didn't have the right spanners for the job as a result.

 

For goodness sake, what type of inland boat mechanic who does not carry set of imperial spanners as well as metric ones. I know most car mechanics, especially younger ones, probably don't have or need imperial spanners but a lot of older boat engines use imperial spanners. If the mechanic is not a car or truck one doing you a favor it may be time to look for another one.

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10 minutes ago, Tony Brooks said:

 

For goodness sake, what type of inland boat mechanic who does not carry set of imperial spanners as well as metric ones. I know most car mechanics, especially younger ones, probably don't have or need imperial spanners but a lot of older boat engines use imperial spanners. If the mechanic is not a car or truck one doing you a favor it may be time to look for another one.

I agree. I've since contacted someone who appears to specialise in listers which I think is a far better option! 

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1 minute ago, SweetPromise said:

I agree. I've since contacted someone who appears to specialise in listers which I think is a far better option! 

 

Good, from memory I think the SLs used imperial nut sizes, probably AF rather than BSF/Whit. That means three sets of spanners needed, metric AF & Whitworth to match all engines properly.

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Many older engines end up with a mix of fittings as things get changed, or slightly damaged and bodged back together in a hurry to get moving and the bodge holds up so never gets changed. It does help to take them all back to the same standard over time as it makes work easier, but it isn't impossible to work with a mixture and sometimes it is nearly impossible to do otherwise (try finding 5/16" fittings for example when 8mm fittings are a near-perfect match).

 

With regard to the current leaks, some good advice has been given. A few things which I would add from my own experience.

 

Diesel creeps a long way. That can make it difficult to work out exactly which joint it is coming from. Cleaning and drying everything and then checking which end gets wet is a good start. So, for example, on the filter fittings you need to find out whether it is leaking from the joint between the filter body and the adaptor, or the adaptor and the copper pipe, or both. If it's just one then for now you can leave the other alone.

 

How practical are you? If reasonably so then damaged threads are fairly easy to repair. If you can get the thread to hold with a tap then great, but otherwise there are cheap helicoil copy kits on Ebay which work perfectly well. The challenge is to then get a seal - the original metal to metal won't work round the helicoil but you can seal it effectively with various things - a couple have been mentioned, to which I would add Wellseal as an alternative option. If you are not so practically inclined then finding a replacement filter body would be easier. It is likely to have the part number stamped or cast on it somewhere and a search on Ebay, Midland Chandlers or L&S Engineering are all good bets for finding a matching one. Any filter body will work, but the mounting and the pipework are designed to fit this particular one.

 

Replacing olives - copper pipe is pretty cheap - measure the outside diameter to find what you need and buy a short roll. Olives come in packs from either a plumber's merchant or Ebay. They are handy to have around. I tend to use brass olives on fuel pipes. If you haven't installed an olive before, it's very easy. Cut the pipe end square across, clean off the burrs on the inside and outside (there are tools for this but it can be cut with a hacksaw and deburred with a craft knife, or even a kitchen knife, with care) and check that the pipe and the olive do not have scratches or other damage on them. Slide the nut up the pipe, then slide on the olive. Push the pipe firmly into the fitting to make sure it's properly in, slide the nut and olive up against the fitting and screw on finger tight. Check it's aligned squarely in the fitting and then tighten up with a pair of spanners (one on the nut, one on the fitting), making one full turn. Check whether that has sealed and if not, add a quarter turn. It should not be gorilla-tight! Things not to do - tightening the nut with a single spanner on the nut when the article the other side of the fitting is an aluminium casting as it will probably strip the threads.

 

Hope that helps!

 

Alec

Edited by agg221
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I am far from sure it is a good idea to advise Helicoiling the lift pump or filter head bosses if they have split. I would certainly say it would be bad practice.  If they have split then a new pump body or filter head is the way to go in my opinion. Otherwise tightening the fitting into the Helicoil is likely to just expand the split.

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Just now, Tony Brooks said:

I am far from sure it is a good idea to advise Helicoiling the lift pump or filter head bosses if they have split. I would certainly say it would be bad practice.  If they have split then a new pump body or filter head is the way to go in my opinion. Otherwise tightening the fitting into the Helicoil is likely to just expand the split.

 

Agreed. My suggestion to helicoil was a solution to a stripped thread rather than a split boss.

 

Alec

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8 hours ago, agg221 said:

Many older engines end up with a mix of fittings as things get changed, or slightly damaged and bodged back together in a hurry to get moving and the bodge holds up so never gets changed. It does help to take them all back to the same standard over time as it makes work easier, but it isn't impossible to work with a mixture and sometimes it is nearly impossible to do otherwise (try finding 5/16" fittings for example when 8mm fittings are a near-perfect match).

 

With regard to the current leaks, some good advice has been given. A few things which I would add from my own experience.

 

Diesel creeps a long way. That can make it difficult to work out exactly which joint it is coming from. Cleaning and drying everything and then checking which end gets wet is a good start. So, for example, on the filter fittings you need to find out whether it is leaking from the joint between the filter body and the adaptor, or the adaptor and the copper pipe, or both. If it's just one then for now you can leave the other alone.

 

How practical are you? If reasonably so then damaged threads are fairly easy to repair. If you can get the thread to hold with a tap then great, but otherwise there are cheap helicoil copy kits on Ebay which work perfectly well. The challenge is to then get a seal - the original metal to metal won't work round the helicoil but you can seal it effectively with various things - a couple have been mentioned, to which I would add Wellseal as an alternative option. If you are not so practically inclined then finding a replacement filter body would be easier. It is likely to have the part number stamped or cast on it somewhere and a search on Ebay, Midland Chandlers or L&S Engineering are all good bets for finding a matching one. Any filter body will work, but the mounting and the pipework are designed to fit this particular one.

 

Replacing olives - copper pipe is pretty cheap - measure the outside diameter to find what you need and buy a short roll. Olives come in packs from either a plumber's merchant or Ebay. They are handy to have around. I tend to use brass olives on fuel pipes. If you haven't installed an olive before, it's very easy. Cut the pipe end square across, clean off the burrs on the inside and outside (there are tools for this but it can be cut with a hacksaw and deburred with a craft knife, or even a kitchen knife, with care) and check that the pipe and the olive do not have scratches or other damage on them. Slide the nut up the pipe, then slide on the olive. Push the pipe firmly into the fitting to make sure it's properly in, slide the nut and olive up against the fitting and screw on finger tight. Check it's aligned squarely in the fitting and then tighten up with a pair of spanners (one on the nut, one on the fitting), making one full turn. Check whether that has sealed and if not, add a quarter turn. It should not be gorilla-tight! Things not to do - tightening the nut with a single spanner on the nut when the article the other side of the fitting is an aluminium casting as it will probably strip the threads.

 

Hope that helps!

 

Alec

Thank you very much for this easy to follow info. I'm no mechanic but I'm fairly practical so I'll give it a go before paying someone!

 

I'm going to take on board what everyone has said, really appreciate all the help. 

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This is a good place to start on maintenance. The parts are a sensible size with easy access - not small and fiddly or large and heavy - and you can see what you are doing. Success is pretty self-evident and you are unlikely to set yourself up a whole series of later problems by not quite getting it right. Also, they are fairly cheap if it goes wrong!

 

Some other points which might help, since you can't necessarily assume that the correct fittings have been used to start with. It has been mentioned above that this engine was originally all imperial but is currently a mix of metric and imperial. There are three dimensions on a compression fitting - the OD of the pipe (and the corresponding hole through the top of the compression nut and the olive), the thread on the nut and the dimensions across the hex which determine what size spanner you need. The pipe can be metric or imperial, typically 1/4", 5/16", 3/8", 8mm or 10mm. Bigger fittings are likely to be found on the cooling water system but don't worry about them for the moment. The thread on the nut is likely to be 1/4" BSP or 3/8" BSP. If you measure across the outside of a 1/4" BSP thread it is just over 13mm whereas a 3/8" BSP thread will be just over 16.5mm (I am assuming you are measuring with a ruler rather than verniers so the numbers are approximate, but they are close enough to be confident in what you have).

 

The copper pipe and the corresponding other holes are fairly close between imperial and metric. 1/4" pipe is 6.35mm so you can get 6mm pipe to fit through the hole but you have to excessively crush the olive to create a seal and it doesn't work well. You can't get 1/4" pipe through a 6mm fitting but fortunately these don't turn up too often as they are generally only found in microbore gas plumbing. 5/16" pipe is 7.94mm which is so close to 8mm that it is within the pipe tolerance. These can therefore be interchanged, which is good because genuine 5/16" pipe and fittings are quite difficult to obtain whereas 8mm is relatively easy. 3/8" is 9.5mm so this time you can get it to fit 10mm fittings but it doesn't seal easily. What is more common is people trying to get 10mm pipe through a 3/8" hole which doesn't really work and often ends up with scratches/gouges on the pipe end, causing it to leak. As an aside, in an extreme need this can be dealt with by drilling out the hole in the back of the nut to 10mm and it will then fit but the data imprinted on the nut will then be wrong which could cause a headache for someone down the line. You can't bodge a 3/8" olive onto a 10mm pipe with any hope of success.

 

Another key point to look at is how the seal is actually supposed to be created. There are three distinct options. One is to seal on the olive/nipple - these have a male cone on the outer end, fitting in to a corresponding female cone on the part or the adaptor - check that there is a female cone present otherwise it's the wrong type of fitting and won't seal (note, the other seal on these fittings is to the pipe - an olive seals by compression whereas a nipple is brazed/silver soldered on so the internal of the nut is a female cone for an olive to compress the olive whereas the internal of the nut for a soldered nipple is flat as it just has to push it on to the fitting, the seal having been created by the filler metal). The second option is to seal on the thread. Parallel threads have a leak path all the way up the spiral so fittings designed to seal on the thread are tapered - you can see the slight taper on the male thread and it is easily measured. They can be identified by trying to screw them in and finding they only go so far. Tapered threads are simple but not very efficient on sealing area, so are usually used with PTFE tape. Three turns of tape CLOCKWISE on the thread before insertion is ideal - clockwise because then it winds it tighter as you insert the fitting, rather than trying to unwind it and balling it up. Alternatively there are PTFE pastes such as Black Swan which are easier to use and can also be used on other plumbed parts to make the threads run smoothly. Taper threads act like a wedge so can crack thin castings as has been mentioned above so the third option is a face seal. You can spot these because there will be a flat face on the part, designed to seal with a fibre or copper washer. The face could be either at the bottom of the thread or on the outside. For this to work you need a fitting which has a corresponding flat face - if it is internal the thread needs to be long enough to reach the bottom; if it is external the thread needs to be short enough to not reach the bottom. For an external seal you usually need the hex section to be a bigger size to create a flat area between the hex end and the thread. This third type is a good option on things like the adaptors for your your fuel filter and lift pump for example, although it doesn't look to be what is currently fitted.

 

That's probably enough on fittings before you are bored to death, but it's actually quite simple, there are just several options which have been available over the years and when they get mixed and matched it causes problems, so knowing what you have helps.

 

One other observation - your lift pump has AC visible on it, which I suspect means it was made by AC Delco. Your fuel filter unit looks like it might be a CAV one (check the code on the filter element if you can't find one on the unit itself as that will pull up the unit type the other way around as the filter description will include which units it fits). If they are damaged beyond repair then this should give you a starting point in finding replacements.

 

Alec

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Here's a diagram of what would of of originally been fitted. As you can see the fitting had a male cone on it, which would form a seal in the pump. All pipework would originally have been 5/16" which is still readily available. If you need any of these fittings or any other parts then it may be worth talking to Marine Engine Services (Midlands) who I'm sure can give good advice.

Screenshot_20221130-164750_Adobe Acrobat.jpg

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and I think the fitting that should go into the filter head was "different" as well. I recall it used a plain pipe and a sleeve nut with a taper at the end that clamped down onto the pipe to seal when tightened. I am not sure some filter heads did not come with an AF thread, but can't be sure.

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4 hours ago, Tony Brooks said:

and I think the fitting that should go into the filter head was "different" as well. I recall it used a plain pipe and a sleeve nut with a taper at the end that clamped down onto the pipe to seal when tightened. I am not sure some filter heads did not come with an AF thread, but can't be sure.

Many filter heads were 1/2" UNC threads. Not interchangeable.

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