Fuel and filters ( last word....I hope!!)

P

pcatterall

Well-Known Member
Joined
2 Aug 2004
Messages
5,510
Location
Home East Lancashire boat Spain
Visit site
Youve been very patient so far!!
We are currently on board at Nevers and contemplating our next move...contemplation is a slow job as its a nice harbour and town and the weather is being kind!!

Looking at jobs to do and the fuel system is still on the list. I have re-examined the issue with your last comments/advice in mind.

I discover that my primary filter has in fact a drain ( its a lucas CAV f15 with a clear water bowl under the cannister filter. I could not see the drain due to the awkard position.

Before the filter is a simple water bowl and this is my main concern. The glass bowl has a metal cover so it is hard to see if there is water in it. There seems little point in having this water bowl in the system?? as there is a drainable bowl in the primarry filter ( or am I missing something?

I propose to just remove the first water bowl and bridge the resulting gap in the pipework with a female/female connector and guess that it will be an imperial size (5/16ths--3/8ths ??)

I would buy one when next in UK and bring it out for fitting on our next trip.

Does my proposal seem ok as a simple improvement.

The issue was brought home when, at the end of our recent channel, crossing the engine failed as we were just entering Le Havre. We managed to continue on very low revs but with a bloody big ship up our stern it was a bit of a worry.
The first water bowl was full of water but there was non visible in the second ( the primary filter) I would have thought that any water would have just flowed on into the primary filter bowl and that we wouldn't have had problems until that was full of water as well?

If I need to retain the original water bowl then at least I will have to find a way to examine the bowl without taking it off all the time.

Most grateful for your comments/advice
 
Hi

Yes boating as you have been picturizing is a nice thing that is full of adventures. I have also taken boat riding many times but the most adventurous thing is that when boat has no supports i.e. it is all flat. Try sometimes a boat made of full flat boat and driven by wood sticks. :):) :D:D
 
The cav filters do not have a great water trap, or reputation overall. I would install a new large turbine series Raycor filter, replacing both the existing water trap and cav filter. Consider sucking out the fuel from the bottom of the tank and getting the water out. Even the best water traps only do so much and water can quickly damage an engine and/or grow diesel bugs.
 
Last edited:
Our engine had a water bowl then a Racor filter with a clear bowl bowl at the bottom where you could see water. Thus the water bowl was redundant we replaced it with another Racor. One change we made though was to set the the filters up in parrallel not in series. This is what mobos have and if a filter gets blocked you just turn the good one on and the blocked one off. I would strongly recommend it. Make sure you check the bowl for water regularly.
 
nigelmercier said:
I'm a bit confused. When you say "primary filter" do you mean the first one (normally called a pre-filter) or the one on the engine?

Pictures would help.
Click to expand...

Sorry by primary I mean the first filter rather than the one mounted on the engine.
It just seems that a water trap then a pre filter with bowl then the engine filter is a bit of overkill.
I did clean the tanks prior to this trip, there was little evidence of water. I confess to some lazy checking due to complacency plus, of course, the difficulty checking the trap with the metal cover.
I appreciate that I could/should 'modernise' the whole system but at this time want to make the existing system easy to check without l
losing efficiency.
Thanks all
 
From your description it seems the water trap is doing little apart from adding a potential source of air leaks into the fuel delivery system if you cannot see contamination in the bowl.
Once the water trap is full of nasties the primary filter will begin to fill as well. I would diss the water trap.
I second the suggestion of replacing the Lucas pre-filter if you cannot easily get to the drain plug which, by memory, is a 10mm hex head.
The Racor 500, which I have put onto my system in place of a Lucas, has a knurled drain knob at the bottom of the bowl which can be opened by hand. It also has a spout to take a tube which avoids the contaminated diesel going into the bilges.
The other plus is that the Racor filter can be replaced by unscrewing the top, avoiding the hassle of lining up o-rings.
 
Gordonmc said:
From your description it seems the water trap is doing little apart from adding a potential source of air leaks into the fuel delivery system if you cannot see contamination in the bowl.
Once the water trap is full of nasties the primary filter will begin to fill as well. I would diss the water trap.
I second the suggestion of replacing the Lucas pre-filter if you cannot easily get to the drain plug which, by memory, is a 10mm hex head.
The Racor 500, which I have put onto my system in place of a Lucas, has a knurled drain knob at the bottom of the bowl which can be opened by hand. It also has a spout to take a tube which avoids the contaminated diesel going into the bilges.
The other plus is that the Racor filter can be replaced by unscrewing the top, avoiding the hassle of lining up o-rings.
Click to expand...

I second that. Although the Racor body is expensive to buy, it takes all of the grief out of filter replacement even at sea under difficult conditions, takes away the risk of mis-alignment of the o-rings and the resulting air leaks. Well worth the effort
 
Why make work for yourself removing the water trap (glass bowl). The presence of water should be obvious as any water will be at the bottom with the diesel "floating" on top. It is then quite a simple task to put a container under the bowl and undo the drain to release the water. If the bowl is so full of water that you cannot see the diesel then you have a serious water problem.

If the fuel filter also has a water trap then (so what) you have two devices preventing water affecting engine performance.
 
donmerrifield said:
I second that. Although the Racor body is expensive to buy, it takes all of the grief out of filter replacement even at sea under difficult conditions, takes away the risk of mis-alignment of the o-rings and the resulting air leaks. Well worth the effort
Click to expand...

These look very interesting, I may get one when I'm next in the USA. How does one decide the required flow rate?
 
nigelmercier said:
These look very interesting, I may get one when I'm next in the USA. How does one decide the required flow rate?
Click to expand...

Websites should have some good data. Although it is a turbine filter, my little Beta 20 does not demand enough fuel to even turn the turbine, but I was re-assured that this would not affect the filtering and water trapping abilities, although a moving turbine will improve its operation. For me, the biggest advantage is the ease of changing a filter with just one bolt/Tee bar that can be removed by hand, one seal, and a filter that is simply pulled out of the fuel bowl and the new one put back in without any fuel spillage and, if you are careful, without any need for bleeding the system. No doubt what I have is overkill for the engine, but a great result for the operator!
 
The smallest Racor turbine filter (the 500 series) is large enough for almost any engine that would be fitted to a reasonable sized yacht.
There are advantages in going larger however. The 900 series has a much larger capacity before it is clogged, which is very helpful in terms of still providing enough fuel if clogged with a diesel bug problem.
The larger filters housings are only slightly more expensive in terms of initial cost and replacment filters.
They are much physically larger however ( which is why the filter area is much greater) so make sure you have room.
 
You must log in or register to reply here.

Share this page

Top