water separator purging blues

[lindsay]

I have a Volvo 2002 fitted with a prefilter/water separator and a main fuel filter.
The separator is one with the rechargeable cartridge in a transparent cylinder with small plastic tap underneath. No problems purging after only changing the main filter but purging after changing the water separator is a bitch.

The local (French) mechanic says the problem is that the water separator is mounted too high and proposes to lower it. No problem. He also suggests replacing it with a later design which, if I understand correctly, uses a "small metal ball bearing to block the fuel flow whenever there is water in the system". If water is around the motor cuts, you just drain off the offending liquid and, Voila! you start her up again. He says that the current separator only works if you see the water in the transparent cylinder and drain it off immediately, if you do not see it and run the engine, then water will get into the engine. The alternative filter design protects the engine better...he says.

Any comments or experience with this "other" filter

Thanks and Merry Xmas

 

[DepSol]

Anything that cuts your engine whilst it is running unless you fall out of the boat is a big no no in my book. Imagine being in a situation which requires the motor and the ball bearing gets stuck in place accidentally or intentionally leaving you heading towards an outcrop of rocks with no way of avoiding them.

No thank you I would rather water went through the engine or even better check the seperator regulary. I wouldnt have it at all. IMHO.

Dom

I am boating again ;-)

 

[ccscott49]

Well! I would not want anything in my system which would stop the engine running when I least expect it. (Think about it) Whats wrong with checking the filter, just before you start the engine, when you check your engine oil and coolant levels, then if there is any water present, you can drain it into a liccle tin for disposal ashore. There is also a water in filter warning device available. Lowering the filter seems a good id ea, by the way.

 

[davel]

I see your point Dom, but if the water is high enough to trigger the fuel cut off, it's serious enough to cut the engine anyway.

I've no experience of the ball bearing thingies but having had water get into my fuel and cause the engine to cut, I know that it's no simple task to recover from this (drain tank, fuel lines, filter, refill with fresh and bleed).

I now check the water seperator very regularly as well as using a water dispersant/bug eater on every fil up.

Dave L.

 

[Bodach na mara]

Got one fitted. It was supplied by local Lucas depot and comes with a warning notice "not to be fitted to boats or any engine fitted with a hydraulic governor" My Watermota Sea Panther has the CVA hydraulic thingy so I asked about these warnings and got the advice that the engine COULD fail at a critical point but only if you were about to knacker it terminally by trying to run it on water. The hydraulic thing is because these governors have the strange habit of giving a burst of full power if the fuel delivery to them is cut off.

Either way, as you don't want your engine to ingest water, having the automatic float valve seems a good idea. It does not operate until there is a significant level of water in the thing, so if you keep a regular eye on it there should be no problem. I have run with it now for two seasons and have had only a total of about a teaspoon of water. I have been tempted to dump some in the tank to see what happens but although daft, i'm not completely stupid!

Ken Johnson

 

[stubate]

the reason that the system is a bitch to bleed after emptying the water separator is that the lift pump on the engine is such a teeny thing and is not designed for pumping air (which is what you are trying to do when you bleed the system) and for sucking the fuel a long way. the grenouelleur has the right idea in a way inthat if you lower the separator below the tank then gravity will help you out getting the fuel to the separator, however you will then have to suck harder to lift the fuel back up the slope on the other side !!
go back to basics,
you do check the separator every time before using the engine dont you?
if you find you have lot of water in the bowl, ask the question, where has it come from?
if its loads in there its obviously come into the tank from the last fuel intake, if just a bit its probably condensation and is a natural phenominum and can be drained off and forgotten about.
get into a routine, take fuel on, run a bit and check !! if loads of water you will have to let it settle drain the bottom of the tank, either thru the drain in the bottom or bottom side of the tank or thru a tube and suck it out from the top.
never mind fannying about with complicated balls and switches, concentrate your energy on making it easy to get rid of the water. fit a drain valve in the bottom of your tank and if you really want to make bleeding easy, fit a CAV LUCAS prefilter & hosing using the CAV 296 filter element, but most important use the one with a big thumb primer on, these can pump for england and will pump fuel by the bucket load. you can get them from ASAP.com or if you are tight like me, go down to your local car breakers and buy the complete lump for buttons. they fitted them on most ford diesel cars and some peugots. the bulk head fixing is probably the same as your existing prefilter and you can either plump it inline with it or replace it
stu

 

[toad]

While down at your scrapyard you could get one with a built in water sensor and wire a light in to the dash.Some work on two electrodes some on a float switch that only floats in water.

 

[lindsay]

Thanks for all the input, which has clarified my thinking, particularly to Stubate who put his finger right on the problem, which makes the problem easier to live with!

As a low tec, small sailboat liveaboard I also dislike the idea of introducing a potentially rebellious ball bearing into a fuel system which has so far worked perfectly, so much so that I have never had to drain off water from the separator which I do, yes, monitor regularly, tweaking the little white dicky to make sure it has not jammed. Might just try and relocate the separator, though.

Isn't this forum great when we stick just to the technical stuff?