Fuel Filter Replacement for W203 C-Class by mtnman82

By stevegolf
( 1 )

Fuel Filter Replacement for W203 C-Class

Compliments of mtnman82 @ www.mbworld.org

For those that want to replace their fuel filter by themselves, here you go ...

By far, the longest part of this chore for me was trying to remove the 4 funky hose clamps on the original fuel filter. The job would have only taken ~45 minutes (including jacking up the car) if it weren't for those dogs ...

Tools/materials needed:

- new fuel filter

- new hose clamps

- socket wrench w/8mm & 10mm sockets

- torx T-20 screwdriver

- jack & ramps

- trach can lid to catch gas

- pair ofr vice-grip plyers


1) First thing to do is to relieve the fuel pressure. On the m271, the fuel pressure relief valve is between the airbox and the engine head (right next to the oil filler cap). Pop off the spark plug cover to find it. Put a whole bunch of rags around the valve to catch the escaping gasoline (I'd wear some latex gloves too) and push down on the pin in the valve (like a bicycle tire valve) to let the gas/pressure escape. When this is done, you can put everything in the engine caompartment back together again.

2) Now you need to raise the car up on the driver's side. I used a jack and a couple ramps. I jacked the car up far enough at each corner to slide the ramp underneath.

3) Next step is to take off the driver's side belly pan which is held on with 8 - 10mm fasteners and 1 - 8mm screw near the front of the car. Slide the belly pan towards the rear of the car for final removal (after pulling away from the studs).

4) Locate the fuel filter next to the driver's rear tire. unmount the filter by unscrewing the strap holding it in (torx T-20). The top of the strap can be removed by sliding it upwards (it rests in a notch in the gas tank).

5) Once the filter is loose, remove the 4 hose clamps and pull the hoses off. Note there will be gasoline pouring out of the filter and from the tank. You will need to clamp off the hose coming from the gas tank (labelled on the filter - look at the new filter to find i.d. the hose). I used some vice-grips (not too tight, you just want to stop the gas from coming out) on the hose and a trash can lid on the ground to catch the pouring gas.

6) After old filter is removed, put new hose clamps on hoses (or use the old ones ...), install new filter (making sure the hoses are connected to the correct ports), and tighten hose clamps.

7) While the car is still up on the ramps, it is a good idea to start it up to check for leaks and remedy if necessary.

8) After checking that there are no leaks, put belly pan back on and lower car. You're done!!!

First pics: the fuel pressure relief valve, my car up on the ramps, and the belly pan off.

PS - It may take a bit of cranking to start the engine, as you've relieved all the fuel pressure and drained part of the system. Mine timed-out when cranking the first time. It might help to turn the key to the 2nd position and leave it there for a while before cranking, as I think that would get the fuel pump running and prime/pressurize the system.