Fuel Tank leak

[Zagato]

The fuel tank started leaking for no reason I can think of. Yesterday it was fine, today it leaked quarter of the tank all over the ground. As far as I can see, it seems to be leaking just behind the rear diff. It's so bad, I feel sick from the smell just by standing near it.

Is there any explanation for this sudden leak? The car was flawless yesterday. Something like this can't just happen overnight.
Sorry guys, but if this turns out be expensive to fix, I'll have to give up the car to the wreckers yard.

[TJ 450]

Yes, it is likely to be the main fuel feed line. These are cheap as chips and used on various MB models, plus they are very likely to fail if not replaced periodically.

They are used on W123s, so I'm certain you could pick one up from an OEM parts supplier in Canada. It will be about 3-4x the price at the dealer as with a lot of other parts! 

I hope you don't use E-85 fuel, as that is a big no-no with these cars, as it is known to attack rubber.

You cannot drive the car with that fuel hose leaking unfortunately, as it will leak until the tank is empty... it will not stop leaking.

Tim

[Zagato]

Yes, it is likely to be the main fuel feed line. These are cheap as chips and used on various MB models, plus they are very likely to fail if not replaced periodically.

They are used on W123s, so I'm certain you could pick one up from an OEM parts supplier in Canada. It will be about 3-4x the price at the dealer as with a lot of other parts! 

I hope you don't use E-85 fuel, as that is a big no-no with these cars, as it is known to attack rubber.

You cannot drive the car with that fuel hose leaking unfortunately, as it will leak until the tank is empty... it will not stop leaking.

Tim

Ah! Thank you, BIG thank you. I'm so glad the problem is most likely to be something as trivial as a line. I'll have it looked at at a shop.

I use 94 Octane, and two days earlier switched to 92 Octane to save money. Though I have a suspicion that the previous owner used the cheap stuff like 87 Octane. The manual clearly states 91 Octane minimum. Speaking of bad fuel, I should probably change the fuel filters too.

[TJ 450]

When changing the fuel hose, it is a perfect time to replace the filter as the tank will be empty.

Here's a pic of the setup. Even though it is on a 6.9, the setup is similar on yours (although the hose might be the smaller diameter version). The usual culprit is the the thick black hose that comes down from the fuel tank in this image.



Tim

[Zagato]

It's not the main fuel feed line. The shop discovered that the thin cylinder that comes between the feed line and the fuel pump (probably an accumulator) is pierced. So that metal thing is the one that's leaking.

Bad news is, the part is out of stock in Canada and in Germany.

I'm desperate here. Anyone got a spare one of these?

[TJ 450]

I'm not sure what that would be on a D-Jet. I would post some pics of the part as the setup beyond the main feed hose is different on D-Jet cars.

Tim

[Zagato]

In the picture you have up there, it looks very similar to the one at the end of the main fuel feed line. The dull round metal thing.

[TJ 450]

Cool, that's the damper, it's a common part to all MBs of the era, so you should be able to pick up a used one fairly easily.

Tim

[Big_Richard]

i got mine on autohausaz, the new style is 1/3rd the size of that version in that picture

.... And, looks nothing like it..

[koan]

i got mine on autohausaz, the new style is 1/3rd the size of that version in that picture
.... And, looks nothing like it..

Same here but didn't like the look of it so I polished up the old one and put it back on.

koan

[s class]

What is inside that damper?  Is it only a metal can that can be re-zinc plated, or are there diaphragms inside?

[koan]

What is inside that damper?  Is it only a metal can that can be re-zinc plated, or are there diaphragms inside?

Nothing at all, just an empty chamber. I found this out only after ordering a new one.

A perfect candidate for WA plate

koan

[Zagato]

i got mine on autohausaz, the new style is 1/3rd the size of that version in that picture

.... And, looks nothing like it..

The one I found online also looks very different.
The inlet and outlet are on either side of it, but the original has the inlet and outlet at 90 degrees from each other. The former also has some sort of adjustment screw. It's for these reasons, the shop refuse to believe that this part will fit between the hoses, or is even the right part at all.

I'm having it towed to an independant Merc shop to get knowledgeable people to decide.

Nothing at all, just an empty chamber. I found this out only after ordering a new one.

If that's the case, I'll ask to have the damper bypassed. To me, it seems to be a slight design flaw to have such a small metal fuel chamber hanging down behind the rear diff. I'm starting to suspect the great Canadian speed bumps damaged it.

Also: Is the main fuel feed line and the hose between the damper and the fuel pump the same inside diameter? If so, that'll make things alot easier.

[Big_Richard]

What is inside that damper?  Is it only a metal can that can be re-zinc plated, or are there diaphragms inside?

Nothing at all, just an empty chamber. I found this out only after ordering a new one.

A perfect candidate for WA plate

koan

Better not be nothing inside it, they cost $114US, seems a bit rich for effectively a metal hose junction with nothing in it

I will have to pull my old one apart now to confirm this atrocious discovery 

perhaps it is simply the shape of the device and the extra port that take advantage of some complex physics to perform its job... thats what ill tell my self anyway

[Papalangi]

I'm not sure we are looking at the right part.

Which item number is it on page 2 of http://handbook.w116.org/Engine%5C107%5CM117_45%5C073-270.pdf

Michael

PS, I assumed a '1976 450SE since you didn't say it looks nothing like Tim's picture.