[Noodles]

I have done several seals and sender/filter units on W211s.
This one is different and of course is happening on my car.
Came out of the grocery store and there was fuel dripping
from left side of the tank and hitting the ground right in front
of the left rear tire.

The car cranked a few extra seconds before firing up. Once
started it drives fine. But clearly I need to address this.

Anybody else that may have had the same issue please post.

My lower back has a blown out disk and I am really hoping to
get it in with parts on hand and deal with it once.
My gut tells me it is the sender with the filter and regulator
built as one unit. It has never been changed at 151k miles.

 

[Witek_M]

You need to take both covers off and find out what is leaking. Left side could be sender, tank pressure sensor, hose for line going forward or vapor line going to charcoal canister.

How full was the tank?

 

[tjts1]

Its an 05 so it could still be covered by the 15 year warranty. Email MBUSA with your vin number, go from there.

 

[Noodles]

I am about 7 months past the limit on time. Not expecting goodwill from MB but will try.

Noticed something tonight. With everything turned off as soon as I turn the key the sound
of the pump priming has changed pitch and is also louder. It is going to be a few days until
I can pull the seat and inspect it.

 

[ezzo]

My guess is that the filter is clogged causing high pressure at the pump which can also cause seals to leak?
My car is at 240K KM (150K miles) and I fear it will do this to me soon! Anything in the forum that shows how to change the filter and pump as a preventive action?

 

[Noodles]

I am wondering the pressure regulator is toast?
So seeing as it part of the sender/filter that will probably get changed.
If I see something obvious like a cracked fitting on top the unit then it gets changed.

This is the first fuel issue I have had. I am going to be calling a couple of dealers today.

 

[daidnik]

The rear seat and access cover for L/H fuel sender will have to be removed to confirm source of leakage.

You said the seals had already been replaced, but pressurized O/P of fuel tends to develop small leaks in the vicinity of the 90° elbow O/P. Something like tiny cracks in the nylon top of the sender unit.

This can be diagnosed/confirmed by drying out the fuel from the triangle shaped pocket at the top of the unit. System maintains ~40psi fuel pressure even with car off, but just to make sure of system fuel pressure, start the engine and watch the triangle pocket. If the nylon top has leaks, then you will be able to see it slowly fill up with fuel.

In case that is the issue, I attach a pic of a somewhat unconventional fix that I did on my 2003 E320 (which MB declined to offer any goodwill on at ~10mo after 15 yr cutoff, which goes by purchase date).

The fix is still going after a year and some, but uses a pretty special 3M epoxy that is gasoline resistant; almost no change in strength after 750hrs soak in gasoline. It's not for everybody, but it is relevant to this situation.

 

[Noodles]

Once I inspect it if it appears the epoxy could work which 3M product is it?
I saw some scotch weld products and and already have the dispensing gun
with mixing tips.

 

[daidnik]

I assume that you have confirmed that the leak still present is seepage from some porosity or micro-cracking in the nylon cap in the region of the fuel Output.

The special epoxy is EC-9323; datasheet is attached. It may be hard to find but it's the only one I've heard of with the gasoline resistance. I found it on Ebay about 5~6 years ago and it was shipped from Israel. It's used in aircraft assy and I expect that the Israelis were getting rid of it when it was reaching end of spec'd shelf life, so it was pretty cheap to me ~$35.

I googled '3M EC-9323' and found it at a place called Skygeek, but it is pretty expensive there. You might have to do some searching.

For the techno-adapted extreme DIY'r, it's some great stuff to have around. The 3M 'Structural Adhesive' group has some very interesting & useful compounds.

I also used the EC-9323 to fix some cavitation erosion issues on the Al-Mg-Si casting on the W211 rather than buy a new $600 replacement. That repair was about 1.5 yrs ago.

Found it at UK vendor w/ free shipping:

Buy Chemicals

Buy Chemicals at CHETA online marketplace

cheta.biz

Search there and you'll find it. It's still expensive, but they show a 50ml cartridge for $46. Mixing ratio is 2:1 for the EC-9323-2 Black.

 

[Noodles]

Well good news. The leak is fixed.
Being convinced it was from the sender or pump access area I was a bit miffed when I popped both hatches
and they were dry and clean.
I should have racked the car and put it in the air 5 days ago.
The leak was an inch of corroded metal line located on the left side near where the rear left passenger foot well
is located. MB used rubber line about 2 inches long just forward of the the left front corner of the tank ask a
connection. I just cut out the corroded section and extended the rubber hose. Used two Wurth ear clamps
at each end and buttoned it up.
Inspected all of the rest of the metal lines and they look new. The car is very rust free underneath so I have
no idea how the line corroded unless the coating on it was faulty from the factory.

 

[daidnik]

Congratulations,

That was easy and cheap.

 

[Noodles]

Thanks.
It was a shock. I forgot to post that updated parts possibly even the tank was done.
I never asked for it at the dealer. I have to go through my work orders to see if they
did it. My SM can run a VMI to see if they did it or the other dealer I used to work for did it.