Gas leak
 

After I fill my gas tank, gas will start to leak past my gas cap. I have replaced the gas cap with a new one from the dealer and still no luck. I placed a tissue in the gas filler compartment and it is wet, confirming that gas is coming from the cap. Is there any other reason why it would leak. Can my new gas cap be defective as well? When I take off the cap I do not hear any sounds. I would expect a hiss as pressure equalized. Can anyone offer any suggestion?

Thanks.

Stan,

You might try a non-MBZ plastic cap like from PepBoys or Kragen.

The PO of my car had to replace the cap to pass the smog check. The cap held pressure but was so tight, I could barely get it off, partly because I have a little tennis elbow. I replaced it with the nicer metal MBZ cap. It holds pressure but I sometimes see an oily film on the edge of the cap so the seal is not perfect, but it's easier on my elbow.

glenmore
1991 300CE

Just an update to my problem. Upon closer inspection it appears that the previous owner either drove off with the gas pump nozzle or the Hulk was pumping gas causing damage to the filler spout. That put a small crease on the filler neck which did not allow the gas cap to seal well. My mechanic used a brass punch to reset the crease, as well he added an additional rubber gasket to the gas cap just in case. The problems seems to be fixed.