Author Topic: Lister SR2 fuel filter  (Read 297 times)

nssc

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Lister SR2 fuel filter
« on: September 22, 2021, 03:55:18 PM »
Hi all,

I've just got a share in a narrowboat fitted with a Lister SR2 engine. There are 2 fuel filters as per the picture attached, but I'm not convinced the filter cartridges and/or "O" rings have been replaced correctly - there has been a deal of leakage, both of air in and fuel out. Does anyone have a definitive drawing of the internals, please? I think I can see where most of the "O" rings are supposed to fit, but I'd like to be certain, and I'd also like to be sure I have the paper cartridge in the right way round, as they're different in the two filters. If it's not clear from the picture, the filters have the securing bolt fitted from underneath the bowl.

Thanks in advance,
Trevor

cobbadog

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Re: Lister SR2 fuel filter
« Reply #1 on: September 23, 2021, 07:48:04 AM »
Do you know exactly where the fuel is leaking from. If it is leaking from the large "O" ring that sits between the housing and the bowl then it is either cracked, broken or not seated properly. If it is leaking from the fuel lines in or out then tell us what type of fittings are there. If there are olives then maybe they need to be replaced. If there is a flare joint then look for any cracks in the flare.
Finally the air bleed screws if the "O" rings if fitted are damaged or simply they are not screwed up firm enough but do not over tighten. Can't remember what the filter itself looks like but I didn't think there was a top and bottom to them. Would need a pic of what you have and of up inside where it sits to confirm.
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cobbadog

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Re: Lister SR2 fuel filter
« Reply #2 on: September 23, 2021, 07:50:42 AM »
Something that just came to mind about the bleed screws. Some do need an "O" ring and some do not and are a tapered fit so look closely to what you have. Some times after market replacement filters come with an assortment of gaskets, seals and "O" rings and sometime not all are needed. I know when I do an oil change on our beavertail truck that I end up with a seal and "O" ring too many for the job.
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nssc

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Re: Lister SR2 fuel filter
« Reply #3 on: September 23, 2021, 01:17:23 PM »
That's really helpful, thanks - especially about there being more "O" rings than needed! The leak was from the large "O" ring that the bowl seats against. Whoever fitted it hadn't seated it properly in its groove and one side was crushed. I replaced the "O" ring and now the leaks have stopped.

I'm still unsure which way the filter cartridge is supposed to sit in the bowl. The centre holes are different sizes, and I don't know which is the top (see the pictures - I hope). And is there supposed to be a steel washer on the centre bolt as well as the rubber "O" ring?

Many thanks for your help.

nssc

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Re: Lister SR2 fuel filter
« Reply #4 on: September 24, 2021, 09:16:11 AM »
I've found a drawing of the fuel filter internals and it shows that both my units have parts missing, namely the internal spring and washer which I assume is to keep the filter cartridge pressed up against the inner "O" ring. These filter assemblies were both fitted by a boatyard here in the UK, one which we'll never use again. I've attached the drawing in case it's of interest/help to anyone else.

Many thanks for your help on this cobbadog.

cobbadog

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Re: Lister SR2 fuel filter
« Reply #5 on: September 25, 2021, 11:59:58 AM »
Now that diagram is a huge help. That is not the first time that so called professionals have stuffed up. They are not always helpful with these older engines and possibly never stripped one. I had an apprentice stuff up a simple tune up on a chain saw once. Then before leaving I had a quick inspection of it as I knew it still was not right and found a few mistakes which he denied. I gave him a piece of my mind and it was not nice for him which bought the boss out of his office and I showed him what his unsupervised apprantice had done and told him to wipe his @rse with the bill as I wont be paid.
Sorry, back to your little problem. With the metal washer it might fit onto the bolt that holds the bol to the body and the "O" ring fit between the washer and body.
For the missing spring. Fit the filter with the large hole facing up but no "O" ring ontop of it and measure from the top of the bowl to the top of the filter. This is or should be an ideal length spring you need to buy. It does not need to be very strong just enough to hold some pressure against the filter body. We have a hardware chain here that has a section of both extension and compression springs of various gauges and lengths. If you find a light spring and is too loong an angle grinder sorts that out quickly. I have just done something similar recently with a throttle return spring in a Mk2 Villiers carby. Have a close look up inside the body where the filter with the "O" ring should fit to mke sure there is not a step that will require the new spring to be shorter again.
It may also be an idea to check both of your filters to make sure they are both complete. I am not sure why you need 2 of these filter set ups so maybe one is enough for your new to you, narrow boat. Would like to see a pic of it too one day.
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nssc

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Re: Lister SR2 fuel filter
« Reply #6 on: October 04, 2021, 04:14:42 PM »
Quick update - this is a shared narrowboat and the hive mind decided to buy two new filters complete. I'm probably going to do the job next week. Thanks for your help cobbadog - your input helped convince them. I've also ordered some Dowty washers for the banjos.

Now my question is what's the best thread sealer for diesel fuel lines? There seem to be a few options, and I've been warned off ptfe tape by a BSS examiner. Back in the day I'd use red Hermatite (sp?) but that was really a liquid gasket rather than a thread sealer, and I seem to remember it needed to be warm to cure. One of the filters - the primary - is bolted to a bulkhead, away from any engine heat.

cobbadog

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Re: Lister SR2 fuel filter
« Reply #7 on: October 05, 2021, 11:25:27 AM »
If the threads are in good condition no sealant is required. I have been in the situation where a sealant had to be used so I used a product calle STAG Joint paste. I applied it to the thread and tightened the joint and left it 24 hours to sure and that worked fo me.
With the banjo fittings the new soft fibre washers are what makes the seal not the thread so again with the washers no sealant required.
Some fuel lines use an olive fitting which compresses onto the fuel line when you tighten it up. If the fuel line is sitting square in the hole and the seats for the olive to sit into are clean then this should seal fairly well with a slight chance of a leak past the thread.
That was very good advise to NOT use the PTF tape it is not recomended on fuel systems.
Other products are out there and from memory the Loctite range have a very good sealant which is like a gel and use it as directed and it will work.
Is there any reason why thi engine has 2 in line fuel filters? I believe that one is enough.
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nssc

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Re: Lister SR2 fuel filter
« Reply #8 on: October 05, 2021, 03:13:17 PM »
Seems to be fairly standard practice on narrowboats, the first one in line they refer to as the primary and allegedly acts as a water separator too. The one attached to the engine comes after the fuel pump and is also the bleed point. Belt and braces perhaps, or maybe mucky diesel is a thing on UK canals.

I'll check out the Loctite stuff, thanks, though I'll leave the banjos just with the Dowty washers.

cobbadog

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Re: Lister SR2 fuel filter
« Reply #9 on: October 06, 2021, 04:32:33 AM »
Sounds fair running it with 2 filters. I have a large tropical high speed 8hp Lister that had no filters.  So I fitted a water separator and filter from a truck. This gives me the chance to see any water in the glass bowl and easily drain if I ever see any. So really any sort of fuel filter will work on these brilliant engines so long as they are replaced as required. Good luck with your repairs and let us know how you get on.
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