Fuel separator or fuel filter as primary?

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blan321

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My yanmar 2GM20 has secondary filter on engine and a fuel separator as primary. Its a Lucas CAV with alloy head, alloy body with inverted cone and glass bowl below. Never had any trouble but on cleaning found black "soot" on bottom of glass bowl. No water. Tank had red diesel until refill Cherbourg July this year, after motoring back little use.
So I don't know whether I should stick with the separator or change to a primary device with a filter in it. The separator head has been stamped separator, so not sure if i can swap in a filter instead of alloy inverted funnel part.
Only owned boat for 18 months, clear glass when bought and checked.
Thanks!
 
I think it's worth having a primary filter, ideally with a bowl underneath to collect any water. Apart from anything else, filter elements can be a lot cheaper than the secondary filter fitted to the engine.
 
I had one with an element, glass below, and ally base with drain. This is it
https://www.google.co.uk/search?q=d...hXJ0xoKHXvBDvMQ9QEILDAB#imgrc=l5VIO8zxAUkTFM:

The drain is ineffectual because all the muck stays in the glass. I now have a transparent inverted cone shape with a drain, the muck sits on the drain tap. I also keep it on flexible hydraulic hose, so if it looks a bit mucky I turn off the supply just before it, drain it half down and slosh it around to clear the muck off the cone inside. I rarely have to dismantle it, like once in three years, you'll appreciate I put several thousand litres through it yearly, many times as it's a Ford Dover. The only other filters are the pair of Crosland 522/Delphi296 on the engine. I have no fuel problems, tank is forty year old steel. Use fuel set all the time.
 
pvb said:
The drain is only to release any water which might appear in the glass bowl. There shouldn't be any muck in the glass bowl because the fuel in there has already passed through the filter element.
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Which begs the question why have I got two filters in line and the second one gets as mucky as the first?
A lot depends on your engine, newer injectors can have nozzles so much finer than mine, like a biro compared to a needle. The engineer told me if I used some of the finer Delphi filters my engine, which is a bit of a dinosaur, probably would stop after a few hours.
 
fisherman said:
Which begs the question why have I got two filters in line and the second one gets as mucky as the first?
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Perhaps your filter is wrongly plumbed; if the flow is as the arrows on the filter head indicate, the fuel goes through the filter element first (this also helps to agglomerate any tiny water droplets into drops which will fall into the glass bowl).
 
pvb said:
Perhaps your filter is wrongly plumbed; if the flow is as the arrows on the filter head indicate, the fuel goes through the filter element first (this also helps to agglomerate any tiny water droplets into drops which will fall into the glass bowl).
Click to expand...

I mean the filters on the engine which are part of the Ford fit out, unlikely to be plumbed incorrectly. However, this raises another issue which has annoyed me for ever. The filter illustrated in my link, (as do the filters on my engine, and every other similar) have the fuel flowing down through the element. I always thought it would be better to have the muck under the element where it could drop off into the base.
 
fisherman said:
The filter illustrated in my link, (as do the filters on my engine, and every other similar) have the fuel flowing down through the element. I always thought it would be better to have the muck under the element where it could drop off into the base.
Click to expand...

As I posted previously, having the fuel pass through the element first consolidates minute water droplets into drops which are big enough to fall out of the filter into the glass bowl.
 
pvb said:
I think it's worth having a primary filter, ideally with a bowl underneath to collect any water. Apart from anything else, filter elements can be a lot cheaper than the secondary filter fitted to the engine.
Click to expand...

I agree with the setup you suggest , just that in my case the prices are reversed, my primary filter with water separator bowl (Racor R25T)costs 3times the price of the secondary filter on the engine which has a water sensor alarm (Bosch) .
 
pvb said:
The drain is only to release any water which might appear in the glass bowl. There shouldn't be any muck in the glass bowl because the fuel in there has already passed through the filter element.
Click to expand...

My Racor 500FG definitely don't work like that. The fuel goes around the glass bowl centrifuge (if there's sufficient fuel flow) and dumps any water and major dirt and sediment particles and then goes up through the filter which takes out the smaller particles.

It's a very good system because if you get a diesel bug infection or similar you know very quickly because you see it collecting in the bottom of the glass bowl.

See http://www.racornews.com/single-post/2016/1/25/Mythbusters-Fuel-Filters for flow diagram.

Richard
 
Thanks for all the comments. I will switch to filter with bowl, not sure i can run to a Racor, altho the system described sounds ideal. My separator head looks like it has a mixed flow and so may partially bypass a filter if fitted.
 
Take a good look at the way the ports are marked on a cav filter - follow the flow through . The IN ports generally run into the spigot tube - which runs straight into the bowl.
I have seen some marked the other way round though ?
Your call - just swap the ports over if you want it the other way.
 
Generally the flow goes into the bowl first, big water droplets fall to the bottom with any dirt then gets sucked through the filter
 
BelleSerene said:
http://www.ebay.co.uk/itm/482720-Racor-Type-FG500-Diesel-Filter-Water-Separator-Fuel-/281903899186

Follow the advice of the reviewer, and use an original Racor filter, not the one that comes with it.
Click to expand...

+1 I've fitted one of these and wrote about it here. Still happy with it and the glass bowl has already paid for itself when we noticed black crud in it and could deal with it before it could choke the engine.

With two filters in line, they're normally a different pore size, e.g. 30 micron and then 10 micron. If you have particles of both sizes, the first one filters the coarse crud but lets the smaller particles through and the second one catches those, so both filters would turn black.
 
Yngmar said:
+1 I've fitted one of these and wrote about it here. Still happy with it and the glass bowl has already paid for itself when we noticed black crud in it and could deal with it before it could choke the engine.

With two filters in line, they're normally a different pore size, e.g. 30 micron and then 10 micron. If you have particles of both sizes, the first one filters the coarse crud but lets the smaller particles through and the second one catches those, so both filters would turn black.
Click to expand...

That’s a great write-up. The bowl on mine wasn’t glass, BTW - a kind of yellowy plastic. Was yours? It did come with straight fittings as well as the right-angled ones though - although I had to change them to fit my fuel pipe. Still, does a superior job and lets me see any water content and any sediment, which is what I’d wanted for years.
 
pvb said:
I wasn't referring to your Racor, I was referring to the filter which fisherman linked to in post 3.
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I didn't say you were and had no intention of implying same. :)

I was simply stating that my Racors don't work in the particular way you described in your post but work in the "opposite" way, which seemed relevant because the way my Racors work accords with Fisherman's description of his preferred flow route.

Richard
 
BelleSerene said:
That’s a great write-up. The bowl on mine wasn’t glass, BTW - a kind of yellowy plastic. Was yours? It did come with straight fittings as well as the right-angled ones though - although I had to change them to fit my fuel pipe. Still, does a superior job and lets me see any water content and any sediment, which is what I’d wanted for years.
Click to expand...

Thanks. See-through bowl is perhaps a better term. It's not glass, I don't think the original Racor one is made of glass either.
 
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