BUKH engine fuel filter, replacement frequency

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JimC

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Each year I replace the CAV pre-filter element on my BUKH 20 and I have once also replaced the engine-mounted filter - about 3 years ago. The latter is the bowl-mounted type, not the later screw-on cannister. The engine-mounted filter never shows any fouling and fuel drawn off from the bottom of the bowl is always clear, so do I need to change it? It seems as though the pre-filter/water separator is doing the business and stopping any crud from reaching the engine filter.
 
Hi Jim,

I have a Bukh ME10 but clearly have a different filter set-up to you. The first filter after the fuel tank is a CAV type sedimenter/agglomerator with a glass bowl and drain plug. This has no filter element. I have elected not to replace the glass bowl with the metal option because I like to see that the fuel is clear in the bowl. This unit is in the locker beneath the fuel tank and I check the bowl visually each time I open the fuel valve. I look for dirt and free water.

The main filter is engine mounted and is the spin-on cartridge type. Ideally I suppose we should be able to measure the differential pressure across these filters to get an idea whether they are clogging up. I suspect that I could go 5 years without a problem since the engine probably only runs 100 to 150 hours per year but for peace of mind, I change it every second year. I do however always carry a spare. I might be more concerned if I had no confidence in the fuel supplier. I probably ought to monitor engine hours more accurately and not elapsed time since engine hours are really the main driving variable here.

When you change the pre-filter element are you able to see any obvious contamination? If not, I would be inclined to stick to an extended change period but always have a spare to hand. Do you monitor engine hours?
Morgan
 
The engine-mounted fuel filter was changed to the spin-on cartridge type about 1982. Previous engines (incl' mine) had a loose paper element that fitted inside a metal bowl. On my boat (Sarum 28) the CAV water separator also has a filter element above the glass bowl, which I change yearly and which often comes out bearing crud. It is the very common 296 type element which is widely used in commercial craft, lorries & industrial engines. This pre-filter seems to stop anything reaching the engine-mounted filter - hence my query about the need to change the latter.
 
1. I have the BUKH Installation Manual here, and in it there is no mention of a pre-filter being necessary, and none is shown in the piping diagram. The only filter shown between the tank and the engine is the one fitted on the engine. However, the manual does say you can fit a water separator in the fuel line, if you wish.

2. You say that your engine mounted filter was converted to a spin-on type in 1982. Did you do this conversion yourself? The reason I ask is that my engine was manufactured in 1982 and it has the paper cartridge type, which is a messy business to change. I asked at BUKH [UK] Ltd if I could convert it to a spin-on type and was told it couldn't be done [at least not using parts from them].
 
1. Well mine does have the filter and water-separator combined. The filter element is above the water-separator bowl with a long bolt holding them together. Apparently a previous owner wanted a belt and braces solution.

2. I meant that BUKH changed the design of their fuel filters around 1982, not that I had my particular engine converted. As you rightly say, this unfortunately isn't possible. If you have the older design you're stuck with it.
 
The Bukh Workshop Manual recommends changing the engine mounted filter every 300 hours or once a year. In practice 300 hours is probably two to three years of use, so if a pre filter is fitted I would suggest every two years. Engine failure due to a blocked filter is repairable in a seaway, but not an experience to be relished
 
One thing to watch on the DV engines is that at some point the fuel lift pump was changed to a SEV Marchal type with a small filter in the suction side. I have had this block with crud and cause the engine to cut out. The Bukh guys at Poole say that the filter is not available any longer and that I should dispense with it but it has blocked the crud from getting any further into the works so I have kept it in place and clean it at the start of each season.
 
The Sadler with its ancient Bukh came without a water seperator. I was advised to fit one, and it seemed to make sense.

But I have only changes its filter once in 4 years. I can see that its clean and has no water in it, so am happy to have an infrequent replacement regime.

As has been mentioned the main diesel filter is of the old type, paper cartridge, and is a pain and messy to change. So if anyone knows of a conversion kit I would ove to know of it.
 
Years ago in conversation with a wily old engineer, talking about engine oil filter changes, he midly rebuked me and asked why I did not concentrate on the fuel filter system. Given the choice, it was preferable to change the fuel filtration system as often as maybe to keep a clean fuel supply to the lift pump.

I have never deviated from this advice and pass it on - if in doubt, get it out and put in a fresh filter!

PWG
 
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