August MBM leaflet (fuel filter change)

[DAKA]

Page 75 photo 4ii refers..........

Changing a prefilter can be cut short by filling the prefilter with diesel before screwing it back together.

The leaflet also suggest filling the engine filter in the same way "with clean diesel".

This could be incredibly risky causing break down and or expensive repair, as both filters have been bypassed the importance of using "clean" diesel (being prefiltered to 2 micron and kept in lab conditions) is vital................


Unless of course the mucky diesel is poured directly into the filter inlet hole/holes only, that way the diesel will be filtered.

I missed the bit in the leaflet that identified which holes were which.

Does anyone know which holes are which ?

Is the single centre hole the inlet or the outlet ?

 

[andy59]

I would think that the outside of the filter paper is the inlet ( larger surface area ) . BTW , love the diagrams of the various fuel systems , notice all the fuel tanks have drain cocks , not had a boat yet with those fitted .

 

[DAKA]

I guessed at the middle hole as there is a baffle to separate water on a spring at the base, and I couldnt get my head around the engineering to allow the water drain off at the base

Mine is a pure guess, you make yours sound like an educated guess, how sure are you ?

There are loads of diagrams and big photos..........aka padding

 

[PCUK]

This has been standard advice for years and never caused a problem. Fuel is passed either way through the filter depending whether it is fitted for agglomeration or filtering.

 

[LittleShip]

I missed the bit in the leaflet that identified which holes were which.

Does anyone know which holes are which ?

Is the single centre hole the inlet or the outlet ?

The outside are the inlets. Just like the oil filter

Tom

 

[Chris_d]

I alway do this and it saves bleeding the system, technicaly you are correct but if you are filling the filter from a clean source straight from a pump surely one filter full of "unfiltered fuel" is not going to cause much of an issue when the flow rate is gallons per hour.

 

[DAKA]

Its a practice Ive used for years on the pre filter, 1 litre of diesel by passing the pre filter isnt an issue as the engine mops it up.

If a litre of 'clean' diesel is allowed to also bypass the engine filter then the risk is a particle gets stuck in one or more injector nozzle , it would cost hundreds to find and loads of wasted hours.

'clean' diesel is stored in a plastic can which contains plastic particles, the leaflet then shows it is then poured into the filter through a ribbed plastic spout which has been stored with both ends open to dirt, hair, spiders yuk !

NB
Im not an expert, if latestarter or someone of similar standing comes on and passes it off as good practice then by all means listen to them, in the mean time I suggest caution and only pour the **** into the pre filter, the engine filters have a convenient pump fitted and bleed screw anyway, how hard is it to do a proper job ?
WTFNS in a heavy sea would be an argument for taking a short cut but not an annual service in my opinion.