I know dumb question,but how often should these be changed.Reason why I asked is both of my Benz's side by side and I noticed how black (barely see through it) the pre filter is.Is it for good diesel health every 3k miles like an oil change,or every other or what?Thanks

mdhh,change the black filter now,or else you will be in for a tow to tne shop when your eng stops for lack of fuel.the rule of thumb I use is to change my primary and secondary every10000 miles,but I know my station where I get my diesel fuel,it is water /debris free,but when I take a trip of several thousand miles,the first thing I do is change the fuel filters,because of ouestionable stations along our interstates.
Good luck.

Tom Brown, Va Section
1995 E300 diesel 110K
1995 C220 (hers) 41K

...and it doesn't hurt to carry spares. I carry two pre-filters and one main, just to keep Murphy at bay.

Cheers,
Wes

Maintenace schedule is at 30,000 unless you suspect plugging. I've not had any plugging problems, have only changed the filter on the Volvo twice in 65,000 miles.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

mrdhh,

I replace my filters at exactly the right time, every time. That time is when the filters have a noticible effect on engine performance. Since they are such an easy thing to change, takes about 5 minutes, I usually do it away from home when on a long trip because that is when they seem to plug up.

A misconception is that new filters filter better than dirty ones. Not true. As the pores fill up the passages become smaller and filter out smaller and smaller particles until the filter's passages are so small they start to restrict the passage of the fuel molecules. That's when it time to replace the filter.

When to replace the filter is not proportional to miles, its proportional to the amount of dirt in the fuel. So replacing fuel filters on mileage is illogical. If you have perfectly clean and algae free fuel, the filters would last the life of the car.

BTW, always carry spare filters and you won't need that tow job.

P E H

Either your filter has been there for a long time, or you have an algae problem.

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member