Water in deisel tank and black primary filter.

steve yates said:
I like the idea of a vacuum gauge, it seems a very useful tool. Would I place it after the primary filter?
I presume they come in different dimensions depending on the size of fuel lines hose etc?
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Yes, you simply tee it in to the fuel line between the primary filter and the engine. It then measures the amount of suction needed to pull fuel through the filter. They tend to use standard pipe sizes, but it's easy enough to make up an adaptor.
 
yodave said:
Hi Steve,

I've just gone through the process of cleaning out the tanks. See here; https://macwester.wordpress.com/2017/03/20/fuel-system-overhaul-2017/

It was a pain, but now that it's done I have a lot more confidence in the fuel supply. Not convinced that alternatives like fuel polishing will deliver that same peace of mind.
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Thanks Dave, just read that post. Interesting that you have sailed since 2011 with that crud at the bottom of your tank with no problems :) I do wonder how many tanks out there are in a similar state. Presumably the filters are doing there job.

A new tank in the winter is definitely on the cards though.
 
steve yates said:
I like the idea of a vacuum gauge, it seems a very useful tool. Would I place it after the primary filter?
I presume they come in different dimensions depending on the size of fuel lines hose etc?
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For mine I put a T-piece in the line between the primary filter and the lift pump on the engine. You need to find the diameters of the fuel line and line to the gauge in order to find the right sized T-piece. The vacuum gauge itself cost, IIRC, €7 from Banggood.
 
I replaced my steel fuel tank when I got my Moody 33 several years ago. The tank was/had been leaking so that was the first job when I bought it. The only way to remove the tank is to remove the engine then the tank ... So I cut it into 3 places insitu, revolving the tank which I suspended from the boom. I used a recriprocating saw - very quick. I replaced with a Plastic tank, Plastimo from memory, 91 litres, to replace a tank about 3 times the volume! This gives me about 30hrs + of motoring, more than adequate(25hp Beta). I dose with Marine 16 at every fill up and even now find traces of gunge in the primary filter each year.


a new tank in the winter is definitely on the cards though.[/QUOTE]
 
Just looking at the yanmar diagram, and what I am calling the fuel filter, which was black, seems to be some kind of primary filter, fitted into the fuel line before it reaches the engine. The fuel filter itself, what I called a secondary filter which was in not too bad a state, is longer and slimmer and situated up on the engine, up above the dipstick and impeller.
 
That's the same terminology I use. Secondary filter is the one on the engine, with a finer filter. Primary filter is, in my case, a CAV before the fuel gets to the engine.
 
Ok, so we are going to add a delphi/cav water separator to the fuel line before it even reaches that primary filter, are they purely to filter out any free waer or do they filter crud too,so effectively having double filtration before the actual fuel filter on the engine?
 
They filter out most of the crud, bug etc. The secondary filter is a finer one to catch what gets through. so multi-stage rather than double filtration, if you know what I mean.

The CAV type filters usually separate out water too
 
steve yates said:
Ok, so we are going to add a delphi/cav water separator to the fuel line before it even reaches that primary filter, are they purely to filter out any free waer or do they filter crud too,so effectively having double filtration before the actual fuel filter on the engine?
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The water separator primarily allows water to separate out. Any significant bits of crud should settle out too, but there's no filter function as such.
 
pvb said:
The water separator primarily allows water to separate out. Any significant bits of crud should settle out too, but there's no filter function as such.
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The one we have selected is a Delphi filter element above a deepish glass bowl which should be easier to inspect than the shallow ones, we did consider just the bowl (sold as a 'sedimenter') but since the problem is more bits than water now, decided the third filter (10 micron) might help. it will be outside the engine compartment before anyone chides me for using glass.
 
Quandary said:
The one we have selected is a Delphi filter element above a deepish glass bowl which should be easier to inspect than the shallow ones, we did consider just the bowl (sold as a 'sedimenter') but since the problem is more bits than water now, decided the third filter (10 micron) might help. it will be outside the engine compartment before anyone chides me for using glass.
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That's not what people call a water separator then. CAV used to describe it as a filter agglomerator. Be sure to plumb it correctly, following the arrows cast into the head. 296 filters are as cheap as chips, so get a few spares as it's going to catch all the muck.
 
Couple of useful wee videos on servicing CAV and Racor filters on the Seastart website, they cut the top off a big plastic coke bottle to contain the fuel. There is no doubt that Racor 500 series is the bees knees but at ten times the price for the assembly and the elements , (the replacement elements are dearer than the whole CaV kit) hard to justify. Plumbing connections are also harder to fathom.
There was a Racor 500 on the Nimbus I owned briefly last year which impressed me for convenience until I found out the price. Steve's CAV will be on a bulkhead in a locker behind the engine so relatively easy to reach.

I just used the terms used by SSL diesel on their website, They seem to sell a lot so I thought they might know what to call it, or if not might be using a description in common use.
 
I'm considering the design of fuel tanks in general. Most authorities seem to recommend the take off an inch or so off the bottom but this allows crud to build up below this which can then be disturbed by rough seas and stop the engine at a very inconvenient time. This has happened to me personally, a couple of sailing friends and on a blog i watch (svdelos.com) so it's fairly widespread. So would it make more sense to have the take off at the base of the tank avoiding having a dead space where debris can accumulate and a seperate sump with drain so that the dregs can be removed periodically. This together with duplicate filters in parallel and regular dosing with bug preventer should prevent most problems.
Also an inspection hatch is essential but not easy to provide on many boats.
 
I think that will be a mistake, if you have water or dirt in your tank why do you want to move it toward the engine. A sump or low corner from which you can pump out the heaviest part is a good idea but in boats draining that by gravity means constraints on location or size of the tanks and still could be a messy job.
My solution would be to use materials that do not rust, buy clean diesel or pass it through a filter, keep water out, keep the tank as full as possible, use Soltron and if you do not manage all of this, sample the bottom of the tank by regular (annual) extraction from the lowest corner into a clean white bucket, tilting the boat can help with that.
I have a simple plastic hand pump with a long semi rigid inlet pipe which is kept for sampling diesel from boat tanks, I also have a clean white plastic bucket to pump it in to, water or dirt is easy to spot in it.
 
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I like the idea of drawing fuel from the sump.
It means the inevitable small amount of water is removed as quickly as possible, to the filter bowl where it can be seen and removed.
It's not rolling around the bottom of your tank having surface contact with lots of your diesel.

It's similar to what happens in cars, and I've never known a car get diesel bug.
 
It would obviously be easier to do so there must be a good reason why no boat builders want to do it, most diesel vehicles are used more frequently and not many are laid up for half the year or sometimes longer.
 
Quandary said:
It would obviously be easier to do so there must be a good reason why no boat builders want to do it, most diesel vehicles are used more frequently and not many are laid up for half the year or sometimes longer.
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My old Hallberg-Rassy had, as a standard fitting, a little brass pump mounted in the engine compartment, fixed to a pipe which drew from the very bottom of the keel tank, so any water could be drawn off easily.
 
Quandary said:
It would obviously be easier to do so there must be a good reason why no boat builders want to do it, most diesel vehicles are used more frequently and not many are laid up for half the year or sometimes longer.
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I suspect the water and bug aren't supposed to reach the dip tube until the boat is out of warranty?
Obviously in the short term it means the system won't be stopped by a few litres of water from a bad fill or a leaking deck filler.
In the medium term, leaving water in the tank is a breeding ground for diesel bug and additive salesmen.
 
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