Emergency fuel tank

[Kelpie]

Not sure I'd fit a brand new CAV filter, unless like me you have a stock of filter elements to use up....

OTOH Racor elements are ten times the cost. So I change my CAV filter if I think I've heard the slightest hiccup. With the Racor, I don't carry ten spares so I don't change it unless I'm pretty sure there's a problem.
Admittedly I've never had a problem getting a Racor to seal, whereas the CAV is a different story...

 

[mrangry]

Hi, thanks for the input, yes this has been changed. I haven't bypassed the filter yet but will see if I can rig something.

It is worth doing as these can be a known weak spot

 

[fisherman]

I always wanted the system mentioned elsewhere in the thread: bilge fuel tank constantly feeding a day tank, which has a large overflow back to the main tank. Any problems you can run off, and top up, the day tank, which of course is high enough to not get air problems.
Older French trawlers had a hand pumped day tank, you had to go below every so often to do it so the engine room got checked over.
(Modern boats with engine room cctv get an insurance discount.)

 

[Stemar]

When we were very new to sailing we found out the hard way that our engine had two filters.

T shirt acquired .

The first one blocked as we left a crowded East Head. Fortunately I was able to get the genny out in a hurry and sail to a safe place to drop the anchor again. The second caused the engine to stop a few seconds after dropping the mooring pennant. No wind and a couple of knots of tide, so the only option that didn't involve impact was to drop the anchor which, inevitably, hooked a trot. Never did get it back, so it's probably still down there, a cable or so inshore of the old Rame Head mooring.

 

[Gixer]

Not sure I'd fit a brand new CAV filter, unless like me you have a stock of filter elements to use up....

I do have a new one of these which takes the same filters as the one I was going to take off.
Water Fuel Separator & Diesel Fuel Filter

 

[Crinan12]

I feel your pain Gixer
I recently had similar issues

I did what someone else suggested and by passed the primary filter - I just put a length of hose from the engine fine filter into a clean Jerry can. It ran no problems so I knew the issue was upstream of that
I then took the primary filter and hoses home and ended up discovering a small air leak from the CAV filter bleed screw. I used a dinghy pump to pump air into one of the hose ends and blocked the other end and when I pumped i could hear the air coming out.
Good luck.

 

[TernVI]

...

If I were to fancy a fuel supply project, it would be a twin filter and vacuum gauge system. You can buy them off the shelf at great cost but I think you could put one together for much less from the parts.

Personally, I would be thinking about a system which stopped water and crud from even getting to the filters, a means to remove water and dirt from lower in the sump than the filter is picking up from.
The tanks I've seen with enough water and crud to choke a filter had enough crud in them to choke a lot of filters.
Some cars have an electrical sensor in a filter to detect water, I might consider that.
Likewise, the vacuum gauge could be electronic with a warning attached.

For a boat with big engine and/or big tanks, then a day tank system comes into its own.

 

[ip485]

Personally I am all for redundancy BUT only do it if your redundant system is ultra reliable!

Cans of fuel, dodgy ways of changing supply, using any part of the existing system, all lead me to imagine cans falling over, diesel in the bilge, a blocked filter still blocked, and a redundant system that hsant been used in years being no help at all.

Light aircraft about which I know something usually have two tanks, just about everything non engine side isnt shared, with twins everything, and every flight both sides are tested. Now that is a redundant system. There are those that forgot to check, ran out of fuel at 5,000 feet, switched tanks and Mr Lycoming still wasnt going to play ball for various reasons. Such a shame when there was a perfectly good redundant system.

 

[penfold]

On my boat I have a lazaette which shares the same floor height as the cockpit which is a good foot above the engine. This is also on the center line of the boat so would stop the listing. From this point I will fit new tank, possibly Tek-tank with new A1 rubber hoses to and from the engine though a brand new CAV filter.

Any thoughts on this?

Don't fit a CAV filter, there are much better alternatives. Get a drain point fitted to the new tank to allow water and sludge to drained off, ideally from a sump that will catch water and hold it.

OTOH Racor elements are ten times the cost. So I change my CAV filter if I think I've heard the slightest hiccup. With the Racor, I don't carry ten spares so I don't change it unless I'm pretty sure there's a problem.
Admittedly I've never had a problem getting a Racor to seal, whereas the CAV is a different story...

They're ten times the cost because they're many times better; CAV filters are out of the ark. Racor knock-offs are practically as good and little more than CAV filters.

 

[Kelpie]

Personally, I would be thinking about a system which stopped water and crud from even getting to the filters, a means to remove water and dirt from lower in the sump than the filter is picking up from.
The tanks I've seen with enough water and crud to choke a filter had enough crud in them to choke a lot of filters.
Some cars have an electrical sensor in a filter to detect water, I might consider that.
Likewise, the vacuum gauge could be electronic with a warning attached.

For a boat with big engine and/or big tanks, then a day tank system comes into its own.

The Yamaha outboards I used to work with had a water sensor in the engine filter, mounted under the cowling. The system worked well, after the alarm sounded you just made sure to drain the filter at the end of the day, and then at some point in the next few days drain the tank itself to get rid of water. As far as I'm aware it was just a little float switch in the filter, which must have been set to float in water but not petrol.

Something similar mounted on a low point in your fuel line would be a smart move. I don't know if the specific gravities of diesel and petrol are similar enough to allow the same filter to be used?

 

[rotrax]

Nothings ever simple is it, this adds complication to the system, going to take more planning.
Thanks for the info.

I carry plenty of spare fuel hose, almost half a 15 metre coil. A couple of short pieces of copper tube the right size with hose clips make extending feed and return easy.

 

[rotrax]

I always wanted the system mentioned elsewhere in the thread: bilge fuel tank constantly feeding a day tank, which has a large overflow back to the main tank. Any problems you can run off, and top up, the day tank, which of course is high enough to not get air problems.
Older French trawlers had a hand pumped day tank, you had to go below every so often to do it so the engine room got checked over.
(Modern boats with engine room cctv get an insurance discount.)

Our Kiwi boat has a day tank above the Bukh DV20 filled with an electric pump. The pipes are clear so movement of fuel and hopefully any contamination could be spotted.

Very common in NZ.

 

[ip485]

Our Kiwi boat has a day tank above the Bukh DV20 filled with an electric pump. The pipes are clear so movement of fuel and hopefully any contamination could be spotted.

Very common in NZ.

Great addition!

Use it often, keep it full, know any parts that are common to both systems, know its range, do check the pipes when uplifting, and enjoy.

 

[Stemar]

Don't fit a CAV filter, there are much better alternatives. Get a drain point fitted to the new tank to allow water and sludge to drained off, ideally from a sump that will catch water and hold it.

They're ten times the cost because they're many times better; CAV filters are out of the ark. Racor knock-offs are practically as good an little more than CAV filters.

Big +1 for dumping the CAV. They're 1960s (1940s?) technology and a pain in the bum to change, with two O rings that are clearly different (but which goes where?) on a sunny afternoon on the pontoon, but far too similar on a dark and stormy night, which is when you're most likely to need to change the filter in a hurry.

For the real tightwads, your local car breaker will have a choice of a dozen different filters that take spin-on cartridges that make it daft not to fit a pair in parallel. You could almost certainly find a glass sedimentation bowl that would trap water and show you it's there for not a lot.

 

[Gixer]

Big +1 for dumping the CAV. They're 1960s (1940s?) technology and a pain in the bum to change, with two O rings that are clearly different (but which goes where?) on a sunny afternoon on the pontoon, but far too similar on a dark and stormy night, which is when you're most likely to need to change the filter in a hurry.

Right, you lot have got me really intrigued now. Even though I've got a new filter housing and glass bowl arrangement ready to fit if there's a simpler solution I'm all ears.

Just to be clear, this is what I've got.
Water Fuel Separator & Diesel Fuel Filter
What would you recommend fitting in its place? Bearing in mind its a single cylinder diesel which uses about 0.5L per hour.

 

[fisherman]

Right, you lot have got me really intrigued now. Even though I've got a new filter housing and glass bowl arrangement ready to fit if there's a simpler solution I'm all ears.

Just to be clear, this is what I've got.
Water Fuel Separator & Diesel Fuel Filter
What would you recommend fitting in its place? Bearing in mind its a single cylinder diesel which uses about 0.5L per hour.

I looked at my version of that filter years ago. The fuel came in on top and went down through the filter. I always thought it should go up through so the bricks and water drop into the bottom to be drained out.

 

[doug748]

I have one of these:

Separ Distribution UK - The Filtration Experts

300 quid, by jingo.

.

 

[fisherman]

On my 6cyl Ford I only had a simple transparent separator, about £12 from the local diesel engineers, and the two on-engine filters with a crosland 522 and a delphi 296. Changes up to 600 hours. The separator was on flexi, hydraulic hoses, so I would unclip and shake it up to drop the muck out, very effective. Up to 100 lts/day, but it has to be said the Ford is a dinosaur, with injector nozzles many times the bore of those in a modern engine, the engineer told me 'think biro vs needle' as he pointed to a newish car in the repair bay 'and that's why I'm in business, small nozzles, hygroscopic fuels, high pressures and plenty of nozzle erosion'.
12000 hours and no injector or pump maintenance.

This separator:
https://www.indiamart.com/proddetail/all-tractor-water-separator-21476615055.html

 

[Stemar]

Right, you lot have got me really intrigued now. Even though I've got a new filter housing and glass bowl arrangement ready to fit if there's a simpler solution I'm all ears.

Just to be clear, this is what I've got.
Water Fuel Separator & Diesel Fuel Filter
What would you recommend fitting in its place? Bearing in mind its a single cylinder diesel which uses about 0.5L per hour.

I went to my local car breaker and got a matching pair of filter bodies, Volvo/Renault, but only because they were the tidiest pair I saw. I got four taps and a bit of copper pipe from ASAP and set them up in parallel, with a tap upstream and downstream of each. I was going to use two T taps, but it worked out a lot cheaper to use four on/off jobs. It was a few years ago now, but the whole job cost me change from £50. My fuel is gravity fed, but if the fuel had to be sucked through the filters, I'd fit a bulb pump. With that, I reckon you'd be able to change a filter with the engine running.

 

[fisherman]

I went to my local car breaker and got a matching pair of filter bodies, Volvo/Renault, but only because they were the tidiest pair I saw. I got four taps and a bit of copper pipe from ASAP and set them up in parallel, with a tap upstream and downstream of each. I was going to use two T taps, but it worked out a lot cheaper to use four on/off jobs. It was a few years ago now, but the whole job cost me change from £50. My fuel is gravity fed, but if the fuel had to be sucked through the filters, I'd fit a bulb pump. With that, I reckon you'd be able to change a filter with the engine running.

So do I! BUT, gravity fed are the key words, with all those joints.