Clogged diesel filters - emergency action?

[concentrik]

Having experienced this in trying sea conditions recently I'd like to anticipate any recurrence. We were able to limp into harbour as the engine didn't stall completely, but it might have done - and the palaver over replacing three filters and extensive air bleeding (thanks to previous thread responders) convinced me there was no way I'd be able to do it at sea.

Would it be OK to fit a filter 'complete by-pass' valve to switch the (blocked) filters out in an emergency or would any crud getting to the engine just make things worse, for longer?

What about a vacuum switch/gauge in the fuel line just after the last filter to indicate increased blockage (although I know this wouldn't get me out of a jam, just confirm the cause)

A secondary pair of filters in parallel which could be switched over to in the event of the first pair being blocked?

I WILL drain and flush the tank as soon as possible....

 

[rogerthebodger]

3 tanks with primary filter / water seperator on each and a selector valve for each tank.

Twin secondary filters on the engine again with change over valve.

Completely doable.

 

[prv]

The right answer is a pair of filters rigged with changeover valves. I've just sold a pair that were in my boat - see my post here for a couple of pictures: http://www.ybw.com/forums/showthread.php?359546-Antifoul-drogue-horseshoe-dual-fuel-filters

(I was selling because I upgraded to a similarly twinned pair of Racors, which are rather better albeit the spares are more expensive.)

I have also just fitted a vacuum gauge, though haven't really used it yet.

EDIT: Roger's suggestion of multiple entirely separate tanks each with their own filters is even better, of course, but impractical on most yachts. I also don't have dual engine filters, though I certainly could as my "engine" filter is actually mounted remotely. But I rarely found much dirt in there on the old boat (can't tell on the new one as the filters are opaque cartridges) so I assume it would be far more likely for the off-engine filter to block first.

Pete

 

[NickRobinson]

Second set of switchable filters is the belt and braces (a la RNLI) perfect solution, possibly with vac gauge too

Missing out your blocked filter? I'd consider it on a lee shore, where survival is more important than engine health, but it begs the question about cobbling up the connections at the scene.

If doing it before hand, see option one above!

Nick

edit- note to self- I should really follow this sage advice!

 

[MASH]

Bypassing a blocked filter is a quick road to a blocked injection pump or nozzles and that's a complete stopper.
The parallel filter solution is fine as long as it isn't chronic contamination such as diesel bug or lots of water in which case the second filter may/will block pretty soon too.
Carrying a spare can filled with fresh diesel is another way. (Empty it into the tank and refill the can every time you refuel to keep it fresh) In event of a blocked filter you can take the fuel line off the filter output and put it in the can which you know is clean. That will at least get you the last few miles into safety.

 

[NickRobinson]

In event of a blocked filter you can take the fuel line off the filter output and put it in the can which you know is clean. That will at least get you the last few miles into safety.

Not if the pump return line is sending fuel back to the main tank... ( I realise what you mean and we both know parallel filtration is the proper solution-)

N

 

[MASH]

Nick, so the pump is returning your clean fuel to the tank so your little can won't last very long, is that it?

 

[Spirit of Glenans]

Did'nt PBO have an article about how to install a primary filter on a parallell loop with a manual valve within the last couple of years?

 

[NickRobinson]

Nick, so the pump is returning your clean fuel to the tank so your little can won't last very long, is that it?

Yes, unless there is no return and the spill-off and pump surplus is tee-ed back into the feed (like my little Yanmar)

Apparently the returned fuel is many times the volume of the fuel used.

N

 

[yoda]

Parallel filters is the answer to the problem of changing and bleeding at sea. Cleaning the tank and fuel is the answer to the cause of the blockage. Believe me I know!

Yoda

 

[ukmctc]

not impossible, I changed two blocked filters in a force 7, in a narrow channel, it can be done, and fast.....

 

[Talbot]

If you add FuelSet every time you fuel, this will no longer be a problem.

I had very bad bug two years ago, and had to sail back into my marina. My own fault, new boat and had not started the FuelSet treatment then. I ran the fuel through a strainer to get the worst of the **** out, had the fuel tanks steam cleaned, and then replaced the fuel (still as black as anything I have seen) - treble dose with fuel set, wait two days, replace filters and bleed - perfect transparent fuel again and no further problems.

Heard three days later that someone in the same marina had thrown away 160 ltrs of fuel because of the same problem.

 

[concentrik]

not impossible, I changed two blocked filters in a force 7, in a narrow channel, it can be done, and fast.....

Now I do feel inadequate! Fast? How long should I take to remove, discard, re-fit, prime and bleed? Only slightly tongue in cheek, because relying solely on being able to do it this way, when I could fit a backup pair of filters and have them ready would seem a bit foolhardy. Anyway it has taught me that I need to be prepared, to have tools, filters, disposal bags and rags to hand - and to have the knowledge before I need to use it!

 

[Steve_N]

I'm sure it's been mentioned before but the quickest and cleanest way to bleed CAV-type filters is to pull the fuel through a spare output port on the filter head using a Pela extractor or similar pump, presuming that you have a free outlet port on the filter head and that you have an oil extractor of course..

Undo the centre bolt and drop filter and glass bowl into a cut off 2 litre milk container.
Swap the filter element and bolt it back on.
Take out the outlet port plug, push in the extractor tube (wind a bit of tape around it to make a snug fit) and pump until the bowl has filled and clear diesel is coming out.
Replace the plug and you're good to go - no need to even open the bleed screw or operate the lift pump etc.

I have both primary and secondary CAV296s and have always used this method - never yet had to do any other further bleeding than this and you can get both elements changed (although the secondary has always been pristinely clean) in about 5 minutes.

 

[fisherman]

A plastic outboard tank with a filter mounted on it, or on its fuel line, with a suitably sized end to jubilee clip onto the engine inlet. You then have the squeezy bulb to prime up and get going fast. However, there will be filters between the lift pump and injection pump that would need changing if blocked, rather than the primary filters. I carry enough fuel in 25lt cans to get me home, but I have to rig a syphon in the engine room. An outboard tank would be much easier and safer, and could be on deck with a long delivery, come to think of it.

 

[MASH]

If you add FuelSet every time you fuel, this will no longer be a problem.

then replaced the fuel (still as black as anything I have seen) - treble dose with fuel set, wait two days, replace filters and bleed - perfect transparent fuel again and no further problems.

I admire your confidence in fuel set but some of it's claims are a bit extravagant, such as "removing water" which can only be done by magic I suppose.

What bothers me is where all that black muck went; it's sculling around the bottom of your tank just biding its time and waiting for a nice 3/4 empty tank and a F7 I reckon, unless fuel set magiced it out when no one was looking too...

 

[KellysEye]

>Parallel filters is the answer to the problem of changing and bleeding at sea. Cleaning the tank and fuel is the answer to the cause of the blockage. Believe me I know!

Agree that's what I changed to and also have the same sentiment of believe me I know, from experience.

 

[NormanS]

The real answer to prevent having the problem in the first place, is for all fuel tanks to have sumps/dirt-traps fitted. This means that any dirt or water doesn't get a chance to swill around in the tank at all. You know it makes sense.

 

[GrahamM376]

A plastic outboard tank with a filter mounted on it, or on its fuel line, with a suitably sized end to jubilee clip onto the engine inlet. You then have the squeezy bulb to prime up and get going fast. However, there will be filters between the lift pump and injection pump that would need changing if blocked, rather than the primary filters. I carry enough fuel in 25lt cans to get me home, but I have to rig a syphon in the engine room. An outboard tank would be much easier and safer, and could be on deck with a long delivery, come to think of it.

I carry a spare 25L can of diesel and, with flexible hoses can disconnect from primary filter and run the feed and return into the can. With electric pump, bleeding not a problem.

 

[fisherman]

I carry a spare 25L can of diesel and, with flexible hoses can disconnect from primary filter and run the feed and return into the can. With electric pump, bleeding not a problem.

Yes likewise. My ideal would be to have a service or day tank above the engine with constant circulation and filtering from the main tank, gravity feed to the engine. This would need an extra lift pump to service it, as the injector pump needs about 5 psi which is 16ft of diesel.