Since we might be encountering diesel of dubious quality south of the border (or perhaps better, who knows), it’s a good idea to know how to change your fuel filter. We buy OEM filters at the Mercedes dealerships and carry a few spares, just in case. They’re about $50 and probably a bit cheaper online. We’ve heard OEM suppliers are either Mann or Mahle, so probably best to go with those.
The fuel filter sits underneath a heat shield below the air filter housing, right in the center of the engine compartment. It’s not a very convenient spot unfortunately. To change it, let the engine cool off a bit, as there can be some hot parts around (including the filter itself).
We haven’t been able to find much information on it online, so here’s the step-by-step guide:
- Torx bits
- 5mm hex bit
- Flathead screwdriver
1) remove the air filter housing. This requires 5 steps: 1) use a flat head screw driver to pop up the air vent on the 2 plastic connectors. 2) disconnect the black plastic air hose on the driver side (snaps off easily); 3) remove cable on the driver side by sliding upwards; 4) loosen clamp on passenger side and remove air hose; 5) remove 2 electrical connectors from passenger side. Important: do not turn the ignition without reconnecting these 2 electrical connectors – you’ll get a check engine light. After these 5 steps, you can pull out the air filter housing and put it off to the side.
2) next, you remove the heat shield with a Torx bit. There are 5 spring-loaded screws that turn 90 degrees to detach. You can then pull out the metal piece and put it to the side.
3) the fuel filter is now accessible. To remove it, 1) open the clamp on the back side of the filter cage using a 5mm hex bit; 2) loosen the clamps on the 2 high-pressure hoses attached to the filter and pull them off; 3) disconnect the electrical connector by pulling it out. You should now be able to lift the fuel filter out of its housing (there is a hose in the way but you should be able to get past it pretty easily).
4) with the fuel filter out, you now remove the 2 Torx screws on top of the filter, remove the plastic screw on top, and twist the black plastic insert that sits in the filter, once you twist it slightly, you can pull it out of the fuel filter.
5) there are 2 rubber O-rings attached to the plastic insert. Your new filter should come with new ones. Take the old O-rings off (a flathead screwdriver might help), make sure the new ones are lubricated (you can use old engine oil), and replace them. Then put the insert into the new filter, reattach the 2 Torx screws, and put the black plastic screw back on (some oil might help again).
6) put the fuel filter back into its casing in the engine compartment, reattach the high-pressure hoses, tighten the clamps, attach the electrical connector, tighten the clamp on the housing. Make sure to reverse all steps from step 3.
7) reattach the heat shield plate the same way you took it out. It slides into 2 pins in the back, and attaches with 5 Torx screws that only need a 90 degree turn.
8) put the air filter housing back on (it hooks in on the rear side), and make sure to reattach the 5 things from step 1.
One thing we’ve done to our setup (and this is where it might be confusing for others): the fuel filter comes with a connection at the top that loops around to a spot on the passenger side, which is just as inaccessible as the filter itself. This connection is supposed to be used to check the liquid inside the fuel filter in case of problems. Since it’s equally inaccessible either way, you can remove that connector. If you ever have an issue with fuel quality, you can just attach a windshield wiper hose to the plastic connector on top of the fuel filter and drain the content of the fuel filter more easily.
Another thing on the clamps for the high pressure hoses on the filter: the OEM clamps require a special tool (most people use pliers and run into issues tightening them. When we bought our Sprinter, it had aftermarket clamps installed that were biting into the rubber hoses. We replaced them with a 13mm and a 15mm clamp that tighten using either a hex bit or a flathead (these should work). It’s something to consider. The clamps don’t have to be super tight, the hoses don’t come off that easily.