expansion tank

[Taleb]

hi all ,

my car doesn't have expansion tank and the fuel smell inside the cabin very bad  , is there solution to stop the smell without replacing the expansion and the ventilation line ?

[Pawel66]

What kind of ventilation system does your car have?

A serious smell of fuel, as you know, may not be caused only by this. I would not drive a badly fuel smelling car until I find and fix the source of the smell, which is often a leakage. This is very dangerous, particularly in your climate. And finding a leakage is about following all the fuel lines and smelling and touching all connections.

The lines for fuel expansion tank and for breathing in a regular set up start in the fuel tank and you can get to them by unscrewing the cover (inside the trunk, aft wall) of the fuel filler pipe. You will see three lines coming out of there. Check for the leaks. Check if the rubber cone is hanging in the back right corner of the car under the floor. Check if it is not clogged (just blow air and listen to the bubbles in the tank).

I do not know where the two other lines go in your case (those that usually go to the expansion tank). Plugged? If you have those plugged and if the line out with the rubber cone on its end is connected to the tank, every time you accelerate or you have a sunny day - it will smell because you will be leaking fuel through the cone or venting odours. Then the smell is blown back to the cabin, particularly while driving wiothout a top.

If you have any type of enclosed evaporation system - many more tanks, valves, filters and a connection to engine intake. I am not fluent in this.

[Taleb]

Hi Pawel ,

Thanks for the information , I have just restored my car and I discovered that the  ventilation system it’s been cancelled from America.

[Shvegel]

You will need some form of tank.  Simply running hoses from the tank through the floor of the trunk will not work as the tank allows for expansion as the fuel warms up as well. The tank from before 1969 would be the easiest as you would need to connect the two hoses Pawell mentioned which are under the cover in the trunk that covers the gas tank filler neck.  The third line goes through the trunk floor and ends in a cone shaped fitting.  Luckily it seems that any tank from a 1968 and back Mercedes should work.  You may have to add some hose etc but the function is the same.

[Pawel66]

Taleb, I would start from removing that filler neck cover and look at the two "nipples" in your tank there - if they are there in the form that you can attach a piece of flexible hose with a clamp at all to them. If they are there, the simplest is to follow Shvegel's advise. The pipes go along the trunk back wall, being held by clamps - they are, actually, fun to install. The expansion tank is placed on the right side of the trunk - it is fixed to the side panel by clips. If you do not have the cut outs for clips, you may fix it with double sided adhesive. Then place it as high as the length of the lines allows and to the back.

The two lines go (depending on the model of the tank, butr as Shvegel suggests):
nipple - short flexible hose with clamps - metal pipe - flexible hose (I used clamps here as well) - expansion tank

Important is not to mix the connectors in the expansion tank. The one with bigger distance from the other two and thicker is the line for the cone fitting under floor.

If the connectors in the expansion tank break, the metal part of the thick ballpen refill has a perfect diameter. The tank is not so easy spotted. The pipes and hoses I think I bought from Mercedes, as well as clamps and screws and the cone fitting.

Do not underestimate the cone. It is highly sophisticated cone designed by higher level physics rules. Its shape is creating a bit of vacuum as you drive, which is what you need 

Maybe you have some system there that was used in the US?

[Taleb]

I can tell you guys are expert ....let me do it then I will get back to you ... thanks a lot

[Pawel66]

Here you have one (late version) on e-bay.

https://www.ebay.com/itm/Mercedes-Benz-W113-230SL-250SL-280SL-Expansion-Tank-for-Fuel-Tank-OE/263242208639?hash=item3d4a75557f:g:qbwAAOSwrhBZDMx2&vxp=mtr

I think the most difficult topic here is to get one. Installation is fun.

[sandcrab59]

I never knew what the purpose of the cone shaped rubber was for, at the end of a line coming from the fuel tank.
As Pawell explains , it creates a vacuum.
I have not been under my 280 or 250SL for a while, so I do not know if it is there.
But I am familiar with this cone on both of my 300SD'S.(82 &83).
It is in front of the left rear tire under the floor.(Under the rear seat left side).
When ever I go to junk yards I collect them when ever I find them.
I only see them on diesel cars.
Tom

[Pawel66]

I know this from this site. I was rebuilding this "system" 3-4 years ago because my wife did not like the smell of gas and I read all I could find about it. It was all here.

This vacuum creation is not that obvious to me as, when engine is on high revs for instance, the fuel is sucked on a high rate and vacuum is created inside the tank anyway. The pressure inside the tank depends on a lot of factors (net fuel consumption, temperature, car motion), but apparently there are cirumstances that some slight vacuum is needed there.

The cone (boot) is available form Mercedes A1114710181, costs about USD 15, no VAT (some of these prices are crazy!). There is also a clamp for it (N916002010100), but form Meredes you probably will not get the correct one. I used Norma 10mm.

By the way: I just realized why I have these 2 holes in the trunk floor neer the rear right wheel well. Now I see they are for the new venting system. I had my trunk floors replaced, they came with these holes and I had to plug them.

[Taleb]

Hi pawel ,

I have just ordered new complete system from Mercedes company to replace the old one .

[Pawel66]

Some time ago when I wanted to do it, they were NLA...
Good info, thank you!