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Old 11-06-2003, 08:41 AM
Marshall Booth
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Mercedes fuel filters are scheduled to be replaced every 30kmi, but I have found that with a little care on my part to buy fuel from reliable vendors, modern fuel delivery methods provides fuel of sufficient quality to often allow the filters to last MUCH longer. I have several that are fine after 60-80kmi. I do eliminate any water in the fuel several times a year with fuel anti-freeze or anti-gel, so any residual water trapped by the filter is sequestered and consumed.

Signs of fuel filter contamination is usually a restriction to full flow. This only occurs when the engine is fully loaded and you are at relatively high rpm (4000+). A quick check is to measure the acceleration from 0-62 mph (0-100 km/h) and when it creaps up a second or two, it's probably time. When the weather gets cold, if you've not been diligent about filling in winterized fuel, as the fuel starts to cloud (that's at about freezing) a slightly occluded filter will allow the wax particals to restrict flow and power will be restricted (the engine will usually start and idle okay). A slightly restricted filter will paradoxically often result in INCREASED fuel consumption. If you are driving largely in the city (where maximum power is seldom required) this increased fuel consumption may be the first signs of a clogged filter.

Just ONE load of "bad" fuel however, and you may need to change filters even if you put in new ones YESTERDAY! Use only OEM filters (Mann, Hengst, Knecht, Bosch are all OEM for Mercedes fuel filters).

Marshall
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