Fuel Cleanliness

[widman]

I just spent a couple of days looking at diesel fuel through the microscope. Got samples from a couple of Mercedes trucks that had bad injectors. The green stripe is 80 microns. These samples are drawn through a 0.8 micron patch.

Also picked up samples of filtered diesel from a couple of places

And people wonder why injectors don't last. The amazing thing is most diesel trucks and pickups do not have filters on their tank breathers. Just an open tube to the dirt under the chassis between the wheels.

This was my F550 when I bought it (one tank had this little cap, the other open, but they all have to breath.

This is the breather I put on (although I'm going to move it to a cleaner place)

 

[The motor guy]

Yeah my truck has two those also except they don't even have a cover. I bought the kit at the dealer that has a hose and a breather at the end. I don't know why they didn't put it on at the factory but it's on their now.

 

[Eddie]

I think modern gas vehicles have closed systems now. I'm surprised diesels don't to.

 

[widman]

Right, many of the cars vent into the intake. But diesels vent into the air. Probably because of the environment. Diesel doesn't evaporate much, gasoline does. The extra 10 feet of hose on a $50,000 or $200,000 truck can't be justified by the bean counters.

 

[Eddie]

I have seen my Texaco gas station change their fuel filters and on the filter is stamped 5.0 Micron. I guess that is some help but, not enough with an open diesel tank. I can only hope that diesel engines have a large, quality fuel filter between tank and fuel pump. )

 

[widman]

On board filters are currently not very good. Holes burn through them with the electrostatic sparks of pushing a non-conductive fluid through a conductive filter.

And that 5 micron filter is probably "nominal", or 50% at 5 um. Still better than an oil filter.

 

[TC]

At least for gasoline injectors, it appears they have pin movement of about 0.06 mm (60 microns) to achieve droplets of the same size, or 50 microns per Nippondenso. Hengst fuel filters are rated down to 2 microns.
http://www.densoaftermarket.com/fuel-injector.php
http://www.parker.com/literature/Racor/Mobile_The_Micron_Rating.pdf
http://www.hengst.de/conpresso/_data/Vertriebsbroschuere_en_low.pdf