gas smell and gas cap

[userzweig]

I've had a gas odor in the passenger compartment off and on for the 12 years I've owned my 1971 280sl, and I finally figured out that the problem in my case is the gas cap.

First clue: the smell is strongest when the tank's full.  This makes it more likely that a little gas will leak out and find its way into the trunk, where for some reason it immediately smells up the passenger compartment.

Second (definitive) clue: I now have 3 gas caps -- 2 locking, and one non-locking.  I never have any smell if I use the non-locking one.  I think this is because it sticks into the tank farther and seals a lot better.  Problem is, it's kind of ugly (brass with two little fins sticking up to turn it with), and when gas is expensive and I park in certain neighborhoods and the tank is full, sometimes the tank isn't so full any more when I get back.

All 3 caps have new gaskets.

Caliber sells a replacement locking cap for $145.  Seems like a lot.

Does anyone know where to find replacement gaskets of different thicknesses?  I'm thinking that an extra thick gasket might fix the problem in the original locking cap.

Bruce

[merrill]

Bruce,
so, just to check, you have eliminated the fuel sender unit gasket and the vent tube lines?

can you swap the cap gaskets? is one rubber and the other cork?

I had an intermitent fuel smell and it turned out to be the sender gasket and vent lines had deteoriated.

Matt

[Cees Klumper]

Sometimes the problem is with the filler neck being literally bent out of shape (the flat surfaces where the gas cap catches). If that is the case, one cap may do a better job at sealing than another, but if it's remedied, maybe your locking caps also will do the job (they ought to anyway).

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[Raymond]

I got a chrome, MB logoed, locking cap from my dealer for far less, but that was over a year ago.  (With, just what I needed, another key.)

I also had the aroma in the car and replacing the three little vent lines inside the trunk solved the problem immediately.  There's a thread on this from over a year ago and I think it had photos.  It's worth a try, not difficult, a good preventative even if you don't need it, and still cheaper than any cap.

Ray
'68 280SL 4-spd Coupe

[114015]

Agree to Ray's comments,

Your problem is not the gas cap but the vent system of your tank. The latter seems to be clogged.
Our original gas caps (0004712030 and 0004714730) are of non-vented type. Thus, this can't be the problem (with the exception of leaking).

Try to pry off all vent lines from the tank and the overflow canister and clean them with pressurized air. Make sure not to blow the dirt into the canister.
However, it is not unlikely that you also have a rust (& dirt) problem of your tank which will always give you similar clogging problems again.
Have you already checked that?
Anyway, try to clean the vent lines first. The gas smell will disappear.

Good luck, keep us informed
and
best wishes,



Achim
(Magdeburg, Germany)

[waltklatt]

Also in addition to Ray and Achim, pry off the white plastic lid in the center of the trunk floor to see if the float seal is intact.  If you can see stains or stronger gas smell, the cork or rubber seal is giving out.  
Walter Klatt
1967 220SL-diesel
1963 230SL-gas