How To Replace The Fuel Filter / Water Seperator


I am using a filter from Partsource #GF1916 make by GKI cost $25.07 + tax, it does not include the water sensor, you have to take the old sensor off and install it onto the new filter.

The sensor is plastic and a bit difficult to remove and install, there is definately a chance of breaking it.

If you only have one vechicle or need the car for work on Monday I would recomment buying the filter from Mercedes, it comes with the water seperator installed cost about $130.00 and then removing the sensor from the old filter and keeping it for next time using the GKI filter.

1. Jack the car up as high as you can get it, I recommend getting all 4 tires off the ground although you could possibly get away with just the rear end, however it would make the job harder.

I used ramps for the front and jackstands for the rear. (in the photo I used hydraulic ramps on all 4).


2. Remove rear belly panel.

3. The filter is on the driver’s side beside the fuel tank, you can't miss it. Put a drain basin underneath it. (this is my parts car, 130,000 km on original filter, that's why its a parts car)


4. The filter is mounted to a metal bracket, the correct way to do it is to remove the bracket,it has an E-Torx bolt at bottom and leave it hanging on the fuel lines, then loosen the clamp and slide the filter out of the bracket and remove the crown shaped plastic sleeve. If you don't have an E-Torx you can remove the clamp bolt and bend the bracket arms out of the way leaving the filter hanging on the fuel lines. (probably not the best in the long term due to metal fatigue plus a bit harder to reassemble, have to use visegrips to hold clamp closed enough to start screw)



5. Disconnect the electrical connector on the water sensor; it has a small locking tab on the side.


6. Loosen the black drain plug/air vent at the top 3 or 4 turns and turn the filter upside down to drain the fuel out.

7. Remove the two metal hose clamps on the two lines into the filter; use a small common screwdriver or an awl to pop them open. Other posts have said that you can reuse them; I believe that they are like cotter pins, intended for one time use only. 7/32- 5/8 hose clamps are only $1.09 ea.

8. Pull the two fuel lines off, really hard, lots of twisting, (remember which one is which)


(If you have the complete filter from Mercedes go to step # 12)

9. Now you have to remove the water sensor from the filter, unscrew the drain plug and the two torx holding it on. There are two tangs over the plastic lobes, you have to use a couple of common screwdrivers to rotate the sensor out from under the tangs then carefully pry up evenly on both sides, be careful, it's plastic. Pull out the sensor. (photo shows the sensor rotated)


10. Replace the two O rings on the sensor that came with the filter.


11. . Now for the hard part, lubricate the O rings with vaseline, use lots on the top one. Insert the sensor into the filter, I had a real problem with this the first time I did a filter, I was working outside in my unheated garage temp around -2. I couldn't get the sensor all the way into the filter let alone rotate it into position. I brought the new filter into the house to warm up for a day. At room temperature it was a little bit easier, not much, I was really afraid of breaking the plastic. I ended up using visegrips and common screwdrivers to get it into position. I think that maybe the manufacturing tolerences on the aftermarket filter may have been off a bit.

Install the 2 torx screws and drain plug.


12. Slide the two hose clamps on the fuel lines and re install the fuel lines on the filter (remember which one was which) and tighten the hose clamps.

13. Hook up the electrical connector.

14. Install a hose on the end of the drain plug, Put on Safety Glasses (fuel spraying in your eyes is not good) get someone to turn the key to position 1, you will hear the fuel pump run, loosen the bleed screw to let the air out. The pump will run for 9 seconds and shut off. Have you helper turn the key off and on again until you get fuel without air coming out of the vent. (Be careful it squirts a long way if the hose comes off) Have helper turn off key, and then tighten bleed screw.


15. Put the wavy sleeve back on the new filter then reattach the filter to the bracket and install the bracket.

16. Install the rear belly panel.

17. While I had my car up on the stands I painted the driveshafts and changed the transmission fluid. (See evilutions website)

18. Lower the car back to the ground.


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re #14. It is not necessary to bleed the air out of the lines. I simply turn the key to #1 position, wait the 10 secs, repeat x2. It self bleeds.

Have done this at least a dozen times - no issues.

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Hello Canman,

I was looking at this wiki on replacing the fuel filter, and I'm very interested in your hydraulic ramps; where did you get them? They would certainly save tons of time jacking the car up for service...



(St. Catharines)

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Your  tutorial was excellent! I do have a couple of thing to add that I learned that saved me some time and frustration.


#1.I learned form servicing my other diesel a big truck, to drain the fuel filter puncture the underside with a pointy chisel or nail, with a drain pan underneath, go have a coffee/beer and continue with step 4. By step 6. the filter should be mt take your time having coffee/beer and not more than one of the latter, LOL


#2. If you are using the jobber fillers and have to remove the water sensor after removing the torx nuts bending the tabs back with a pair off needle nose pliers allow more room to twist the sensor back and forth while prying it out.


#3 If you are going to service your smarty invest in a set of torx sockets/bits a cheap crappy tire/princess auto se will work fine and will save you money in the long  run not to mention the money your already saving DYI


As to dank1945"s interest in access i'd love to have Canman"s hydraulic ramps  but I'm cheep $200 in lumber and hardware and you have a set of ramps!a forum.jpgb forum.jpg

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that bleed valve on top...where does it get fuel from?..from the bottom of filter or top?


im curious if bleeding it would eject water without having to change or invert the filter

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About draining water out of fuel filter.



Photo is Canman's from his first post.


Drain cock sits on top of water sensor.  Pipe integral of sensor extends to bottom of well where water collects.  Opening drain cock and running low pressure pump will therefore force any water out.


Sensor itself is only two electrodes fitted about 10 mm apart.  Water conducts electricity whilst fuel conducts to a much lesser degree.  Sensor works similar to the instruments used to check water in brake fluid or humidity in wood.  The higher the water level the lower the resistance measured between the two electrodes.

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