More Bleeding Problems

[Talbot]

For those who were interested in my saga of air in the diesel lines, I thought I would up-date you. I used a piece of transparent hose and connected it into the lines between the tank and the final transparent fuel filter, slowly moving the tube between the various parts of the system. This way I was able to find out that the air is actually coming into my system via the water seperator/main filter (a delphi) I tried tightening all the connections on the filter and replacing the filter element, but it doesnt make any difference. As soon as I rev up the engine considerable amounts of air seem to be sucked in (very visible through the transparent tubing) At least this was the cheapest part in the whole system to replace!!!!!!! I am now more than happy that I know how to bleed my system!!!!
Why cant they add a decent smell to diesel fuel, it stinks.

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[aztec]

make sure your tank is vented properly. if it's not it'll try to develop a partial vacuum with the motors running. another cause of air getting into the pump.

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[Oldhand]

Haven't had a problem with my Delphi yet, I wonder if overtightening distorted something. Racor make good alternatives to the Deplhi and some have a little hand pump which can be a great bonus in hard to bleed systems.

At least the stink of diesel should warn you there is a leak!

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[Talbot]

Stink of diesel was from all the pulling apart of the system and relocating the transparent pipe to different sections of the system. Everytime some diesel was spilt. Will look at the racor as it would enable me to get rid of one part of the system.

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[pvb]

Water separator/fuel filter...

The CAV/Lucas/Delphi type of water separator/fuel filter is very common and reliable. Filter elements are cheap and readily available. Racor filters are very good, but the elements are not as easy to get hold of in the UK.

If your filter is allowing air to enter, there are only 2 main possibilities. It's either a leak on one of the pipe connections on the filter body, or it's a leak at one of the rubber seals.

You can easily undo and reassemble the pipe connections, using a proprietary sealant. You should do the same with the blanked-off connections.

As far as the rubber seals are concerned, a new filter should come with a set of new seals. Have you replaced all of them? Did you put the very tiny one on the central bolt in the right place - you put the washer on the bolt first, then the seal. With a water separator, you also need an additional rubber seal, which has to be bought separately. Have you also checked the plastic drain-off tap on the bottom? If you double-check all these points, there shouldn't be any air getting in at the filter.

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[roger]

Re: Water separator/fuel filter...

There's also the bolt that holds the whole thing together and the connections that are just blanked off. If desparate try covering these connections with some suitable wug.

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[seaboy]

What ever you do, do not replace any part of your fuel pipeline with the clear type of piping with cotton braiding as this will harden with age and start to cause more problems.

One method of testing any fuel line for leaks section by section. Is to fit a vacuum gauge with a suitable connection and check to see that you hold a vacuum. This also checks that your lift/fuel pump is working correctly drawing fuel from its tank.

Have you checked to ensure the fuel line within the tank has a filter, if so, is it restricted causing the fuel line to cavitate creating air.

seaboy

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[clio]

you say youjust installed a new fuel tank? is your fuel return submerged, you may be airiating the fuel in the tank, with the return fuel, thats what it sounds like to me.

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[TheBoatman]

You can buy a CAV water separator/diesel filter for about £50. The filters are cheap and easy to install and readily available. On a boat engine it is unlikely that you will need to change them (filters) every 3 years or so? because you can't get enough diesel to flow through them, don't forget that they are made for diesel trucks and they are doing about a gallon / 10 miles run.
Go buy a new filter/seperator, at least you'll know that, that part of the system is OK.

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[dickh]

Boatman,
I also have the CAV seperator/filter, but you DO sometimes have to change the filters yearly or sooner. I have religiously changed both this filter and the engine filter at every layup, yet mid summer I lost revs, changed the seperator filter and it was back to normal. I cut the old filter open and it was full of crud. I then decided to investigate getting a coarser filter for the seperator/filter but all you can get are 5/7 micron ones - which is the same rating as the engine filter.....
You should have a coarse filter initially and then a fine filter on the engine but the only people(that I've found) who can supply a coarse filter is Racor - for which you need a second mortgage.
I obviously have crud in my tank, and before you ask, no I can't remove it to clean it out as I would have to remove the engine first, and I have used Soltron to get rid of bugs etc. So, I'm resigned to renewing the initial filter more regularly now.


<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[Paul_H]

Talbot

I had exactly the same problem after replacing an old CAV jam jar with a Delpi. Engine would start but revs wouldnt run up. Using clear plastic pipe I could see clean fuel going in and bubbles coming out. Tightening fittings didnt help. I traced the problem to the parallel threads used for the pipe connections . The pipe couplings need decent sized flanges with a fibre washer behind to make a good seal. Trying to seal the thread alone doesnt work (eg. ptfe tape or gunge). Visit your local hose supplier to get the right bits.
PS. I agree that plastic pipe is only for diagnosis, use solid copper or proper rated rubber for real installation.

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[chriscallender]

I would change the fuel filters a lot more than every 3 years - precisely because the fuel sits in the tank unused there are a lot more probs with mositure, bugs & crap in the filter than you would expect on the truck.

As they only cost a couple of quid the only deterrant from doing it is the labour involved in bleeding afterwards, which if the system is well set up should only be 10 minutes worth.

I'm planning to replace my CAV filter with one of the ones with a built in priming pump, hopefully then the 10 minute filter change will be a reality.

Chris

Chris

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[pvb]

Keep dosing it...

Soltron will get rid of your diesel bug problem, but you need to keep adding it every time you add diesel to the tank. It doesn't hurt to double-dose to get the process moving. I seem to have finally cured the bug problem in my tank, but it's taken over a year. I still routinely add Soltron every time I re-fuel.

An alternative to doing regular "just in case" filter changes is to add a vacuum gauge. This will show an increased reading as the filter progressively clogs up, and indicate when it's necessary to change the filter.

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[TheBoatman]

Chris
I didn't say but my engine is only a yanmah 20 so the fuel flow is very low. I do take precautions i.e. keep tank topped up where possible espacially over winter. I try to buy my diesel from sources that I know don't have a water problem and so far the current filter has been in the line for 3 years. I do check it every winter and touch wood no probs yet!

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[saturn]

just some info for fuel leaks,do not use ptfe tape it looks ok initially but soon after will start leaking,its only to be used on air or water.
after removing unions with parallel threads always new copper washer .
if you can, when making up new fittings, use taper thread with a decent hydraulic sealant only.

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[Chris_Robb]

Re: Racor Filters

These filters are available from A S A P - tel 01502 716 993 will arrive probably before you have ordered it - they are very quick.

The Racor filter system is the bees knees

ASAP have a huge range - worth getting their catalogue. Generally good value too

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[DepSol]

Re: Racor Filters

and they sell Soltron too!

<hr width=100% size=1>Dom

<A target="_blank" HREF=http://www.soltron.co.uk>the website</A>

 

[Chris_Robb]

Re: Racor filter price

ASAP charge £8 for 30 micron filter. My mortgage is a tad more!

As to the crud in your tanks - will you not find that in prolonged bad weather, you will pick up more than your filters can handled in a 24 hour period?? Trouble is - as you say - how do you get it out - . Could you not place a long narrow tube down the filler pipe - and suck out at a high rate. If the pipe was drawing off the deapest part of the tank - would not a considerable quantity of gunge be removed?

There might be a case for setting up a second filter that you can just switch over to in the event of a blockage at sea.

Only happened to me once - when I had just bought the boat and was bringing it back in string westerlies from Holland. Silence as water and shit blocked everything. Swore I would never ever suffer again. Luckily the tanks have large inspection hatches, so cleaning can be done annually as a quick job. I think designers/builders who don't allow provision for cleaning should be shot.

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[Chris_Robb]

Re: Racor Filters

Might try some - though I am not sure I need to. I take a litre out of the bottom of each tank every winter - and its absolutely clean. Do I need to use as a preventative - or is this like mis-use of antibiotiocs??

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[david_bagshaw]

Re: Racor Filters

I havnt used solotron so cant comment, have used yachticon, available in europe, which does kill bug.

The real problem when taking fuel off the bottom of the tank is that it onlly takes the crud near the pipe end , so you get an unrealistic idea as to how dirty the tank realy is, leading to a false impression it is clean, soon dispelled after a rough passage when all has been stired up, particularly when the tank is wide & long and not high, so there is a large bottom surface area.


The only way to be really sure is to drain and inspect.



<hr width=100% size=1>David
<A target="_blank" HREF=http://www.euroboating.net>http://www.euroboating.net</A>