PeachParts Mercedes-Benz Forum - View Single Post - Proper fuel filter replacement procedure on OEM603

Jeremy5848 · #7 11-11-2009, 11:18 AM

The FSM procedure is trivial -- remove old filter, install new filter. It's pretty much the same as your old 300D. The secondary filter is perhaps a little harder to get off and on.

The only "tricks" I've learned from this forum, other fora, and personal experience are:
(1) A warm engine will start more easily after filter changes;
(2) A freshly-charged battery is nice if the engine happens to need more than average cranking;
(3) If you use hose clamps (Vice-grips(R) will work if you're gentle), you can minimize the fuel that will leak out of the lines while changing the primary;
(4) The fuel tank should be at least half full and it helps to have the car in a nose-down position so fuel will flow from the tank w/o help;
(5) It's very difficult to get a secondary filter into place while it is completely full of fuel without spilling. Fill it mostly full, then wiggle it into place and put a wedge underneath to keep the filter pressed up against the housing. Now use a funnel to fill the filter the rest of the way and put the central bolt back in place. Tighten the bolt with a wrench, don't turn the filter. Make sure the one or two sealing o-rings on the bolt are in good shape and don't over-tighten the bolt, it's only threading into the filter.

Crank the engine; it should catch immediately; keep the engine at 1000-1500 RPM while any remaining air bubbles are pushed through the system. Check for leaks immediately and after a day or two of driving.

Jeremy