This is a maintenance report on how to replace the W163 fuel filter without removing the seat to pop the fuel tank port. Popping the tank port located under the rear seat and fishing through hoses is a clumsy way to go about this procedure, but seems to be the common thing because the process is technical and detailed and requires care and preparation. The fuel filter is replaced at interval even when running top tier gas. The fuel regulator will be replaced as well since it's integral to the fuel filter canister unit. We all know when filters clog, the fuel pump motor in the tank is placed under stress causing early yet preventable failure. Not to mention of course, a shot filter will starve the engine of fuel causing all sorts of problems from misfire to non-start. The fuel filter interval is 60,000 miles.

Consult service bulletins for vin crossover but it seems by 2002 the new style KL-438 were installed, meaning, you won't have to replace hoses. I have an 05 350 and don't know how it all goes for early MLs, but for later vehicles it's very possible to change the fuel filter without cutting into your car, given the right tools and technique. I was able to take care of this maintenance item today in about two hours total work time, and wanted to share how I did it without removing the seat or breaking anything. The YouTube videos were people popping out the floor port and cutting their poor carpet, and getting frustrated. Totally not necessary! Even though this filter is awkward, it's engineered to be replaceable from the rear drivers side left hand drive wheel.

First off filters. Mahle and equiv. branded KL-438 are unavailable new. They cost $250 on eBay. I just couldn't justify $250 new old stock from Germany or UK, this is supposed to be a regular maintenance item. I landed on parts geek amazon "OEM quality" filters for $60 or so. They appeared to be very fine in quality control and workmanship, identical to every detail to vehicle OEM spec, every weld, pressing, all the same. Very pleased with the quality. Hopefully we will see genuine Mahle KL-438s in stock again but I'm not holding my breath.

Fuel filter pliers are required as is a 14 -16" hemostat (surgical pliers) and some easily bendable steel wire. You can get the Oriley Master Pro fuel line pliers for $15, they are copies of the MB ones and are 100% fine. If you don't have a set of 14 and 16" hemostats buy them yesterday. They are giant locking tweezers and belong in every mechanic toolset.

Once plastic is removed from wheel well, the filter is visible clamped into place. The entire are now must be cleaned. I used a parts cleaner attached to the air compressor blasting water. If you just have compressed air splash it with water first. If just water, spray with the hose on full blast.

The left side, axial connection (toward front of car) has a clip that must be carefully pressed from the bottom. As with all of these connectors, the first step is to "unload" the connector. It is loaded against a lip on the metal connecting tube issuing from the filter body. It must be pressed toward the filter body.

This first, left side (axial) clip is not a press clip. It is a fork that clips into place. The two legs of the fork must be carefully pressed up, then a small flat head inserted into the top of the clip. Once carefully lifted this insert may be set aside for later. It very much seemed that this lateral press in fork could be installed and removed with some additional, special type of connection pliers rather than a mini flat head which is delicate work, because you don't want to break it. I also used a medium gauge wire bent into a staple to push from the bottom but it was a wash; the flat head was almost as easy. Please comment if you what tool pops this fork, gate, thing in and out laterally with minimal hassle.

The next clip to go is the vent line connector, the small connector on the right side, on a tube oriented radially from the filter body and "up". Press this toward the filter body, turning it gently to unload it from the ridge on the connection tube. Then use the hemostat to push the knurled tabs on the connector away from the filter body. If disengaged, the connector will slip off with virtually no resistance.

Now take off the hose clamp completely off the filter body and set aside.

The two remaining clips have the same functional mode and size. Start with the right, (rear) axial port. Press it toward the filter body and gently wiggle the connector to unload it from the port ridge. The special fuel line connector pliers must be used. These connectors work by gently gripping the connector in the "pit", "well", "notch", whatever, on each side of the connector. Gentle force is then applied away from the filter body grasping the connector by these notches. The connector releases when the tab, on the opposite side of the pliers as the filter body, is gently slid away from the filter body. Hemostat and flat head screw driver may be employed to gently coax the connector away from the filter body. The resistance once the connector is properly unloaded and unlocked is virtually nothing.

Once the right, (rear) axial connector has been loosened or removed, the back connector must come off. This is the biggie, what you have been practicing for! It's gotta be done blind, and when you pull the plug gas will start flowing. I haven't figured out how to keep the gas from coming out of the line, please comment if you have ideas such as pulling a vacuum on the fuel tank or locking some solenoid. Get the biggest tray you have and put it under the wheel well, if you work fast 1/8 -1/4 of a gallon of gas will come out and drip all under the car or about 24", so have the tray there and work outside if possible. Prepare your new filter (**see below) and then proceed to removing that blind connector in back.

Inspect your new filter. Orient it in space. Do all the hoses seem to be the same size of the ones you just removed? Check out the orientation of the rear, radial port tube. That's the one.

First grasp the connector on the back side by putting the fuel line pliers around the regulator portion of the filter body, and pull the connector toward the filter body which unloads the mechanism that locks the connector to the port tube, same as the other ones. Then use the fuel line pliers to grasp the tabs. You'll have to do it by feel. Use a mirror and headlamp to make sure you have an idea on the angle of the connector with respect to the axis of the filter body: it was designed such that the pliers can go over the regulator portion and set in the tab notches. Then, grasping very lightly, push the connector back.

Fuel will flow meaning you did it. Gently get the filter out of there.

***Prep this before removing filter: Get a loop of wire 4 inches long, some easily bending steel or brass wire. Loop it around the axial port tube on the regulator side of the new filter body and twist. We want to be able to grab this part of the filter with the hemostat. Loop the wire around the new filter. Then grasp both ends of the wire in the hemostat and roll the stat to take up the wire and "capture" the port tube.

Gas will be leaking at this point.

Orient the new filter in place. The right side, axial port tube has the hemostat loop lassoed around it. Here's why: the back connector needs to come forward onto the port tube using the fuel line pliers around the regulator body. To be able to click it back on, you need to hold that right side, axial tube "back" away from your face (against the force of the pliers holding connectors pulling forwards, toward your face, clicking the tube on.) The hemostat is required: if you grasp the port tube with needle nose you will mar it and create and uneven finish on the interface fit, promoting leaks and seal damage. The wire lasso around the right axial port on hemostats allows you to hold the filter body in place and manipulate it as the rear connector is forced toward the filter body (toward YOU but on the far side of the canister). I'll just say it: there is no better, easier method for install than using a hemostat to wind up a loop that holds the right, rear-of-car axial port tube so you can click the blind side port on to the rear left, radial port tube. Do not attempt any of this if you don't have 16" hemostat , wire, and (even knockoff) angled fuel line pliers at hand, you will have a bad time. With the right tools and gentle, knowledgeable technique you'll be 100% fine.

Test the connection with fuel line pliers. It should have clicked and now be locked against the port tube ridge.

Carefully reinstall the clamp, but keep it extra loose.

Install the right, (rear of car), axial connector in the same way.

Install the left (front of car), axial connector by slipping the two pronged fork laterally back in the connector and clicking the port tube in.

Install the vent tube. On mine the connector was interfering with the edge of the canister such that the connector would not seat fully until the metal port tube was bent outwards <1mm using a screwdriver. If worried about it test the vent line connector on the new filter and bend this little tube forward if necessary. Easy.

Let the filter hang on the tubes. Then tighten the clamp in the most natural position for the sake of the fuel lines.

That's it. Took around an hour to set up, remove wheel, clean area, and then when done button it up, and an hour of actually replacing the filter body by coaxing the connectors off and on. I am thoroughly glad I did not rip into my interior for this. It was easier than I thought it would be. It was tight but very very doable for any patient mechanic. I really sort of love this car and want it to last a long time, so wanted to share a maintenance report that went over how to replace the filter correctly (from the wheel). You can see the port from under the car, and it's clear that if you know how to do it, this is how it's supposed to be done. It all comes down to having the aforementioned tools and knowing how the connectors work precisely before going in.

I plan to repeat this some time again in the life of this car, please let me know if you have helpful techniques or improvements on this process.

Good luck!

 

I found Mahle fuel filter Part#1634770801 but it says it’s for a 2002 ML320. Do you know if this will also fit a 2001 ML320?

thanks

 

Pelican Parts says it will, heres the link,,
https://www.pelicanparts.com/More_In...NT&ByPassCat=Y

 

it says it only fits for 2002 and I have a 2001.

I actually found a Genuine Mercedes filter on EBay and should be arriving this week.

 

Sorry,, It must have been late when I posted that,, Or dyslexic,,, or AADD, or,,, well poo,, glad you found one.
Yeah,, there are some that call it "Fleabay" but If you don't mind shopping a bit you may not find the "Motherload" but there are nuggets to be found at a good or at least better price

 

My 95 F150 started coughing, bucking and dieing day before yesterday. I repl the air filter, added hitest and the same symptoms. I narrowed down to the fuel regulator. replaced it and now runs like a scalded dog.
The main plus factor was, that part on the Ford is on top of the motor and easy to get to, didn't have to remove a heavy seat to get to it. Oh well,, I keep telling myself,,, Quit whinnin,, its a Benz,, To quote " Bobby Mcferrin" don't worry,, be happy"

 

I know the feeling, I’m a bit OCD 🤣. I found the filter for $58 plus shipping so I bought 2 of them and should be good for the life of the car since I only drive 3k miles a year with the ML.

 

Mercedes has a bad habit of over engineering their cars 🤦🏻‍♂️. Many times I find myself saying WTF did they do here