gjunon

Sorry to resurrectt this thread from the dead, but has there been any progress on the fuel filter replacement?

l3iGD

05 E55 wagon now with 94K and fuel symptoms since 80K. Car was a Texas car until last year. Removed viewing plates under seat, driver side sending unit is pooling up fuel. Plastic is yellowed. Pass side basket plastic is white and a sticker reads 2011 so was replaced sometime since then. The green gasket on DS was really ragged out and tore up and the PS, obviously replaced when basket was, already showing cracks in the top of the gasket seal. I replaced both gaskets hoping it would stop the pooling on the driver side. With car on a lift, I siphoned the full tank and put it back in after so the car is full. After driving less than a hour I inspected under the plates again and already a little pooling. I noticed two small hairline cracks when I first looked at it but were hoping it was just dirt that I wasn't able to get to in tight spots. I can now see that they are in fact cracks.

Denroll

Check the stickied threads at the top of the page. MB USA is covering these leaks under warranty.

Take some pictures of the fuel pooling up, then call your local dealer and give them your VIN. They should set you up with an appointment.

Arian86

Hi.

I am in the process of complete the procedure. Except, I cant figure out how to remove the cap on the fuel filter unit! Is it twist or pull? Managed to twist about 3-4 mm by pressing the small pin-clip on the side but the cap is stuck like glue

austingtir

It twist and pulls off myself and someone else did a howto somewhere on this.

coupesedan

These are less than $15 on ebay. As long as it doesn’t wobble around in the housing I don’t see why it wouldn’t work.

austingtir

No there is another how to written by me on here that shows you how to separate the housing and the correct aftermarket filter to buy. Its not that one.

Jonny Garrett

I thought I'd have a crack at this. Removed the sender unit. Seperating the lid was a PITA. I couldn't do it by hand. I had to use two strap wrench's to free them. I have to say this took a bit of effort.
Once seperated I removed the filter. My filter was really dirty. I gave the inside of the housing a clean with some carb cleaner. Got the febi bilstein filter, drilled the smaller hole out to fit. Got it fitting nicely. Then reassembled the top to the sender. I ran out of time and left the unit for 8 or 9 days before putting it back in the tank.

When I finally refitted it on trying to start the car I got no fuel pressure. Also from looking at the pump side I can't see any fuel coming back from the return pipe into the fuel pump wells. Repeated attempts to start transfered most of the fuel to the sender side of the tank. Hmmmmm.

Everything was working fine before removal. I took the sender out again put in the old filter to rule that out. It does have some rubber grommets at each hole that had me wonder. I don't think they matter as fuel goes in from the outside of the filter to the inside and then escapes from the top to the fuel rail and the bottom to the return. So I have no idea what I've done here.

When I did remove the sender again I noticed the now full of fuel sender spilling fuel from the edge where the top and body meet. Now I'm thinking surely this should be a tight seal to maintain fuel pressure? Could this be the reason and why the venturi system isn't working for the return? I'm now thinking that the reason why the top of the sender unit was so hard to separate was it might actually have been a sealed unit. Once the lid is back together it doesn't feel super tight any more and has a little bit of play. Doesn't explain how the OP got his working or was that just luck.

I also wonder what is the metal part at the bottom of sender that has a wire? Some sort of sensor. Could that have malfunctioned?
The other question I ask my self did I screw something up by spraying some carb cleaner into the unit instead of using clean fuel. The carb cleaner was closest to hand at the time I assumed it would be safe to use being a fuel system.

On writing this message is prompting me to go back and inspect the closure of the top in case there is a way to close it tighter that I might have missed .

Failing that I'm about to write this sender off and reluctantly order a new one and this becomes another cautionary tale.

Btw the w211 e55 is a very early model. Dec 2002 but I think it's had the fuel tank problems resolved in the extended warranty according to the local dealer.

Does anyone else have any insights that could help?

austingtir

All sorts could go wrong. Anything from the main housing seal getting pinched to the filter not being seated correctly somehow. Hoses or fittings being brittle and cracking open on reinstall etc etc.

silicone grease helps alot to reinstall.

I would not do this without a method of checking fueling after install like wideband or fuel pressure testing.

SICAMG

How is the o-ring on the housing. They WILL grow when taken apart from fuel absorbing into it.

Jonny Garrett

What o-ring are you referring? Are you talking about the green one on the outside to seal the top of the tank? If so replaced that one as the old black one fell apart on removal. This wouldn't stop the sender working tho.

Jonny Garrett

Not sure what main housing seal you're talking about? I didn't see any. Is this between the two halves - the top and the sender?

I just pushed the Shrader valve, wasn't hard to see there was no pressure.

austingtir

The sender housing you opened to put the filter in has a oring seal around it. When I installed mine it took a couple of goes before I was confident that seal was seated properly.

Anyway its as simple as opening the fuel pump and sender side of the tank and turning on the fuel pumps. It should be obvious once you do that whats going on.

Jonny Garrett

Oh, I see the seal now on the Pmarino how to guide - its inside on the top-side of the unit.. Can't say i remember seeing it but that doesn't mean its not there. I'll have to check that now in case mines fell out or is malfunctioning some way. Mine might be black as opposed to his being green. It would make sense if it's not sealing properly any more

austingtir

https://mbworld.org/forums/w211-amg/...p-replace.html

Jonny Garrett

First chance I've had to look at this again was this weekend. And what do you know? the o-ring in the top part of the sender was missing. I've looked around the garage and can't find it so have no idea where it's gone to so I'll have to replace it. Pretty sure that will be the cause of no fuel pressure.

Can any of you recall the width if the o-ring? Looks like maybe 3mm width with 70mm diameter.

Arian86

Whats the dimension of the green o-ring?

Arian86

Whats the dimension of the green o-ring?