Leaking Diesel from Fuel Fill???? - PeachParts Mercedes-Benz Forum

Robostang · #1 05-20-2012, 11:55 AM

Hello,

I have a 1983 240D 4speed with approx. 324,000 miles. Recently the master and slave cylinders for the clutch pedal were replaced at a local reputable MB shop (most recent work that has been done on the car). Shortly after (about a week) getting my car back I noticed that diesel was leaking down the side of the car directly below the fuel fill and running down the back rear quarter panel and the back right passenger wheel well also appeared to be wet. The fuel tank was full at the time. I washed off the side of the car and ensured that the fuel cap was firmly in place in hopes that would fix the issue but after driving the car the next day there was more spilled fuel.

Fuel only leaks when I am driving the car (the tank is currently about half full) and you can smell diesel from inside the car (while driving) and the trunk has a diesel smell. When the car is parked it does not appear to leak. I have not had time to fully investigate the problem yet (meaning I have not pulled out the passenger side trunk panel).

Hopefully someone here has experienced (and fixed) this issue and can point me in a direction of what to look for. I plan on spending time this upcoming weekend working on the car.

Here are some included pictures (sorry about all the water evident in the pictures, every time I have time to take pictures it is raining).

Thank you in advance,

Jesse

toomany MBZ · #2 05-20-2012, 12:05 PM

Replace the seal ring, or the entire fuel cap if there is rust on the inside.

Also, run some string trimmer line or something similar, down the drain hole.

Murkybenz · #3 05-20-2012, 12:18 PM

Trunk smells of diesel possibly because of the drain tube.

Go inside the trunk and remove the panel that hides the fuel tank.

Look up to the filler cap area and you will see where a rubber hose connects to the drain hole,this hose then comes down to the trunk floor where again it connects to a tube that goes through the floor.

Because you can smell diesel inside the car then either the pipe has come off or is a loose fit at one end or there is a corrosion issue at the trunk floor/tube area where the hose fits.

Murkybenz · #4 05-20-2012, 12:21 PM

This will help
Fuel overlow drain tube question..

vstech · #5 05-20-2012, 05:03 PM

odds are good, that your fill cap gasket is gone, or cracked. your oil fill cap will work in a pinch, but then you'd have oil spraying all over your engine...
as mentioned, the drain tube passes through your trunk, and could be bad. also, your seal around the fill tube is turned in, you could push it out so the lip is up facing outside, instead of down facing the trunk.
likely the diesel is dribbling down the neck, and entering the trunk via the neck seal.

Robostang · #6 05-20-2012, 10:24 PM

Thank you for all of the response and the link to a similar post (guess I should have searched better)!!

I will use something to clean out the drain tube and get the panel off and take a look around. Once I get everything off I will post some more pictures.

It is great to have an idea what to look for!!

Hope you all had a great weekend!!

Cheers,

Jesse

Robostang · #7 05-27-2012, 09:08 AM

Finally had some time yesterday to look at my car. I took all of the panels out of the trunk. There was no fuel in the trunk but there was a fair amount of water. I believe that the rear window seal may be leaking in both corners.

The fuel overflow drain tube is still connected there did appear to be a bit of grit on the tube. The tank looks good and does not appear to be rusty. I am going to drive around the car for a bit with the panels out and see if I can spot any leaks. Also, I am going to get a new fuel cap.

Thanks again,

Jesse

charmalu · #8 05-27-2012, 11:08 AM

Your cap looks good (not rust) just replace the gasket. think a new one is around $2.50. yuours shows the black rubber gasket, there is a blue one that may be a bit thicker, I used one of those and fits tighter. then maybe the old one had shrunk that is why it is tighter.

If the filler neck gasket is dried out and cracked, new one`s of those are still available.

Charlie

Robostang · #9 05-27-2012, 07:29 PM

Charlie,

Thank you for the suggestions I will try them and see how it goes!

Next I need to figure out how all the water is getting in the trunk!

Cheers,

Jesse

toomany MBZ · #10 05-28-2012, 06:24 AM

The usual culprit is the rear windshield seal.

Robostang · #11 05-28-2012, 07:55 AM

Is there a way to reseal (the seal) while it is on the car, or is this a replacement? I am not looking forward to taking the rear windshield out.

Palangi · #12 05-28-2012, 11:10 AM

Usually when you take out the rear window and seal, you will find rust holes under the seal at the curved portion. This happens even down here at the edge of the desert. Probably much worse up there in the rust belt. No way to repair without taking the rear window out.

charmalu · #13 05-28-2012, 12:23 PM

X2

You will most likely find rust once the gasket is removed. I found it in my 85 cali car. Only one way to fix it, remove it and see what you have.

You can Band-Aid it some what, bottom line is, how long do you expect to keep this car, and how is the condition of the rest of the car?

Charlie