Dual diesel filtering fitments

Robih said:
Would you rate the vacuum gauge as an essential part of the setup? I can absolutely see that being aware of an upcoming problem is much better than a surprise! However the gauge is £80 + VAT so near enough £100. This then starts to justify the cost of the pre-formed kits.
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I think mine was under a fiver for the actual gauge. A little more for some brass fittings and tube. Why on earth would you pay £100 for it?

In fact, the one mounted on top of the filters is actually inferior, because unless you have an odd sense of interior design and mount the filter assembly in the middle of the cabin, you're not going to notice the needle creeping up. Mine is next to the steps where I can glance at it on the way out of the cabin - on passage that means hourly after putting the fix on the chart.

Pete
 
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Robih said:
Would you rate the vacuum gauge as an essential part of the setup? I can absolutely see that being aware of an upcoming problem is much better than a surprise!
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The vacuum gauge is useful, as it shows you how the vacuum slowly increases as the filter starts to clog. A big advantage of having a vacuum gauge is that you only need to change the filter elements when necessary, rather than on some arbitrary 100hrs running time, etc. After I fitted a gauge, I found filter changing became rather a rare occurrence.

The advantage of a separate gauge is that you can mount it remotely where it's easy to see. I had mine on the main switch panel. You can get cheaper ones than the Racor, look for one with -1 bar full scale deflection.
 
lw395 said:
I've heard it said that if a filter suddenly blocks, and you switch over, it's very probable that the other filter will block very quickly too.
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I think it likely if the cause is tank crud stirred up in a rough sea. That's why I went for spin-on filters - they're a lot quicker to change and have no O rings to mix up and jump out of their slots when you're head down in a stinky bilge, the boats leaping about and the helm's getting agitated about the rocky lee shore.

lw395 said:
How many people have actually changed over in anger on a sailing boat?
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If in anger means in the conditions I just described, no, but I did have a rather fraught entry into Portsmouth Harbour under sail in a westerly 6-7 after the crud got stirred up. That's what decided me to fit twin filters.
 
lw395 said:
I've heard it said that if a filter suddenly blocks, and you switch over, it's very probable that the other filter will block very quickly too.
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Strictly speaking that's true - but who says the first block was "sudden"? It could have been gradually building up for months, but the engine was coping with it. However, since an engine is either running or not, the stop due to fuel starvation will necessarily be sudden.

(Actually it'll probably drop to idle and/or start racing up and down rather than stopping dead, but the principle stands.)

Pete
 
prv said:
(Actually it'll probably drop to idle and/or start racing up and down rather than stopping dead, but the principle stands.)
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Typically, the revs drop slightly, then recover for a moment, then drop further, as the lift pump struggles to suck enough fuel through the blocked filter. Depending on where it happens, it can trigger rather rapid responses!
 
robmcg said:
Following this thread with interest. A source for a cheap vacuum guage would be good. All the ones I have found are £50 plus!
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You can get cheap ones on ebay.
I've got a couple which are ok, not exactly calibrated to NPL, but were under a fiver IIRC.
You could go solid state and use a vehicle MAP sensor.
 
I have the Racor with centrifuge and a turbocharged 110HP Yanmar and the centrifuge works exceptionally well. I have also thought about replacing the setup with a dual filter. Replacing the drain with a "proper" tap certainly makes draining off any contaminants a whole lot easier. I am guessing that with a new tank of fuel you might just not notice the bowl filling with contaminants before it is too late but that would mean not keeping an eye after a refill. Seems to me you would have to have a really bad tank to actually run the risk of it blocking unexpectedly although you might find having to drain every few hours. I had just one such batch of dreadful diesel with some water and some other rubbish which left the bowl full after maybe 5 or 6 hours of run time but I was well aware of it accumulating.

I am more inclined to fit a fuel polisher given that for a much less budget a single Racor or similiar can be fitted with a lift pump to polish the fuel whenever and prevent a problem before it occurs - but I havent got around to it yet. The other benefit is if you are running diesel off the tank for anything else (a Genset or heater) polishing will reduce the risk of these systems suffering short of thier filters blocking.

Just an alternative point of view. Interested in others thoughts.
 
robmcg said:
A source for a cheap vacuum guage would be good. All the ones I have found are £50 plus!
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You didn't look very hard! Simply typing "vacuum gauge" in the eBay search box finds loads.

You want one which reads from 0 down to -1 bar, size and connection up to you.

Pete
 
prv said:
You didn't look very hard! Simply typing "vacuum gauge" in the eBay search box finds loads.

You want one which reads from 0 down to -1 bar, size and connection up to you.

Pete
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Correct! Previous eBay search bizarrely turned up only gauges from abroad or at astronomical prices or out of a Cessna!:confused:
 
ip485 said:
I have the Racor with centrifuge and a turbocharged 110HP Yanmar and the centrifuge works exceptionally well. I have also thought about replacing the setup with a dual filter. Replacing the drain with a "proper" tap certainly makes draining off any contaminants a whole lot easier. I am guessing that with a new tank of fuel you might just not notice the bowl filling with contaminants before it is too late but that would mean not keeping an eye after a refill. Seems to me you would have to have a really bad tank to actually run the risk of it blocking unexpectedly although you might find having to drain every few hours. I had just one such batch of dreadful diesel with some water and some other rubbish which left the bowl full after maybe 5 or 6 hours of run time but I was well aware of it accumulating.

I am more inclined to fit a fuel polisher given that for a much less budget a single Racor or similiar can be fitted with a lift pump to polish the fuel whenever and prevent a problem before it occurs - but I havent got around to it yet. The other benefit is if you are running diesel off the tank for anything else (a Genset or heater) polishing will reduce the risk of these systems suffering short of thier filters blocking.

Just an alternative point of view. Interested in others thoughts.
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I suspect a common cause of blockage is bug or other contaminant in the bottom of the tank, it sits there for months, then the tank gets shaken up by weather, suddenly you are drawing a lot of dirt/water in conditions where your mind will be on nav and the weather etc, possibly neglecting routine checks of filters.
Maybe it's more of a sailing boat thing, where the tank may be heeled at 30 degrees, you tack and it's heeled the other way?

I tend to agree about polishing, or at least a proper means of removing crud from the bottom of the tank.

Personally, the only time I've had a diesel cough on me in adverse weather, it was air in the fuel due to the fuel being a bit low and the pickup being higher than I thought above the bottom of the tank.
 
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ip485 said:
I am more inclined to fit a fuel polisher given that for a much less budget a single Racor or similiar can be fitted with a lift pump to polish the fuel whenever and prevent a problem before it occurs - but I havent got around to it yet.



Just an alternative point of view. Interested in others thoughts.
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+1
I thought about installing the double swappable filter, but then I built a polisher. I am lucky I have a very well done inspection hatch on the tank so it may not suit everyone, but at the beginning and end of season a couple of half-hour sessions are enough to have an absolutely clean diesel tank. It's actually overkill as the diesel develops very very little sediment (fwiw I use also that Startron thing).
I change the primary filter every 100 hours and basically it's always clean.

To me it's priceless peace of mind when under engine and the boat moves a lot.

regards
r
 
is the vacuum gauge just plumbed into a T junction on the feed from the filter(s) to the lift pump? Do you need to take any precautions to stop fuel flowing back into the vacuum valve? My fuel tank is below the engine, and the secondary filter is slightly lower than the lift pump. If I were to fit a vacuum gauge it would probably be about the same height as the lift pump, or higher.

Neil
 
neil1967 said:
is the vacuum gauge just plumbed into a T junction on the feed from the filter(s) to the lift pump? Do you need to take any precautions to stop fuel flowing back into the vacuum valve? My fuel tank is below the engine, and the secondary filter is slightly lower than the lift pump. If I were to fit a vacuum gauge it would probably be about the same height as the lift pump, or higher.
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Yes, just a simple T-piece. Most people will position the gauge higher than the level of fuel in the system, so no problem with diesel reaching the gauge. If you can't do this, just loop the pipe to the gauge up above the highest fuel level, then back down to the gauge.
 
Bear in mind that small diesel engines can only pull a very small vacuum. ie - My 1gm10 lift pump can pull a vacuum of 60mmhg = approx 1.3 psi. Most cheap guages are 0 - 1 bar ( 29.5 psi ) Find one 0 - 0.1 bar and you will be paying for it !

General vacuum running on mine with clean filter would be about 0.4 psi - which is hardly showing on 0-1 bar gauge.

Many of the spin on/cav filter units with built in primer bulb - actually pump OUT of the head unit - not IN to it. This is not the best system for bleeding the filter head. You can open bleed screws after it in the line - but not the bleed screws to the filter head.

The remote primer bulbs that fit to 14mm x 1.5 or 1/2 unf banjo fittings can be mounted on the inlet side. Or use an inline - good quality rubber primer bulb before the filter unit (don't like them much though for permanent fitting )

I agree with what has been said in terms of - if your tank is clean you are hardly likely to suddenly block a filter. That said - folks do have impossible to get to old steel tanks with no access panels - and dubious internals ?

Rather than spend big bucks on dual filters - I would invest in a new tank and new lines which I can trust to be clean.
If you dont trust your fuel at supply point - fill through a filter funnel.

Oh - and too many joints is not good for the health - learned the hard way !

Geoff
 
nemodreams said:
Bear in mind that small diesel engines can only pull a very small vacuum. ie - My 1gm10 lift pump can pull a vacuum of 60mmhg = approx 1.3 psi. Most cheap guages are 0 - 1 bar ( 29.5 psi ) Find one 0 - 0.1 bar and you will be paying for it !

General vacuum running on mine with clean filter would be about 0.4 psi - which is hardly showing on 0-1 bar gauge.
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Well, I have a 0 to -1 bar gauge and it works fine. Yes, when the filter is clean and everything's running smoothly the needle barely moves off the stop - that's what I like to see. But before I cleaned out the tank the needle would regularly move around in the lower 1/4 of the scale as minor bits of crud obstructed the dip tube and moved clear again. When it actually blocked, the needle would get almost round to halfway.

Are your figures for cruising revs? Or for idle, or perhaps derived from the maximum head permitted for easy starting?

Pete
 
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