Follow Up Question on Diesel Pre filters

Pete,

One issue with using a finer filter either before or after the factory filter is the possible effect on fuel flow. The engines do not like the flow to be restricted. If you go this way you need to find out what capacity (in litres per hour) filter you need.

Cheers

Peter F9
I doubt very much that your factory Ranger filter is 20 microns in size.
For a CRD engine it is hardly worth having a 20 micron as that will allow contaminant sizes which will destroy the system quick smart.
It is more likely the OE filter is around 5 micron as is the Dmax and others, some a bit smaller.

If you draw a circle of eg, 20mm then you can draw many 5mmdia circles in that circular space with gaps in between. So 20micron NO. I would be surprised if it is.

Thinking of the circle sizes, that is the sizes the contaminants get through, so if the size is smaller, and with some filter clogging happening there will be smaller gaps for the rate of required fuel flow to get through without significant restriction.
Therefore as the filter you choose is smaller in micron size, you have to have a corresponding increase in filter medium area size, so no significant restriction is going to occur.
As the finer, more efficient filter is being used it will hold rubbish and begin to restrict. Without sufficient area it will soon restrict and have you, for ever changing expensive filters.

Filter life, usage time/km, contaminant loading/catching/essential flow rate are all items worth considering. Anyone who recommends a filter for a purpose should have a full grasp/understanding of the variables and essential requirement.
Nearly all sellers of that stuff do not know much about them. Only "this is the one we sell" and it is good, take my word for it.

Choose one which fits your purpose and also make sure it is also a Dewatering filter to catch emulsified water, without that you are basically wasting your time as water WILL get into the system. We are trying to minimize the chance of that happening, aren't we?

The bigger the filter area you choose means the flow rate is better and the actual filter membrane flow rate is slower and therefore allows for more chance to catch rubbish and dewater at the same time, instead of hurrying through the filter.

5 micron of a suitable flow and area will be ok. At least 140L/h min, bigger the better.

This applies whether it is before OR after the OE filter.

gday Pete ,
i'm no expert on this but thought i would add my two bob's worth , is it worth fitting a 1 micron filter ( toilet roll type ) still utilising your standard filter ?? I have heard of them being used on diesel trucks for fuel as well as for the oil , with them being used on the oil they are a bypass system , but not sure with fuel as someone has pointed out the flow rate is important .
Not sure what state you live in but Jupiter Steel in either Palmyra or Myaree WA are agents for them ?
Would be interested to hear from other forum members or guests who have have one fitted and if so where it is fitted ??
Good luck mate

Pre Filter should always be larger than the final filter. I had 2 micron to 2 micron on my Cummins diesels on my boat, I inherited it that way. Changed to 10 micron pre filter and kept the final filter as 2 micron. I had various diesel mechanics implement this as standard practice. I think Marine filtration is slightly different but the same principles apply. I am a bit out of the loop as to what people are using on their 4x4's however and would like to know what specific filtration has been developed for 4x4's or people who are often susceptible to dirty fuel. We encountered this once on a boat trip to King Island, we re-fuelled there and suffered power loss on our trip home which was when it was discovered our filtration was not set via best practices.

I would suggest a 30 or 20 micron as the pre filter. I think the primary job of the pre filter is to catch the larger stuff and more importantly to trap any water allowing for a early alarm before the primary, letting the primary filter do its' job of catching the fine bits. this way you can be sure there is no restriction in fuel supply.

Hi Peter, I consulted a diesel specialist whose company does rebuilding of pumps and injectors etc. He advised me not to go below 30 micron. For me I use a CAT filter that is rated at 150 micron (basically a bag in the canister) but I use it primarily for its water separation ability and have connected an alarm. I too was concerned with limiting flow but concluded that the factory primary filter was good and safe enough to filter the end product. I just want to avoid water like my life depends upon it!! hope this helps? Cheers

I'm not that mechanically minded, but have the water watch fitted on my 150 prado, but think maybe better to have a filter/dewater type instead/in place of the water watch, I have heard they are good for there purpose, and it was recommended to me, but who really knows?
Have also heard of running 2 fine filters side by side, as in splitting the fuel flow to over come the restricted flow rate? What do you do? Too many options, one says this, someone else says that...
Should maybe by a pushy...
Cheers. Odog