Over Filling Gas Tank
 

My BMW owners manual (E 30) says never overfill the gas tank
cuz it may affect some emission components.On 2-3 rare
occasions, I did overfilled my MB.Is there any harm done?

Not a problem if it happens only once in a while. The following is a reproduction of a simple explanation.

"Your emission control system actualy consists of several sub-systems, one of which is designed to prevent raw gasoline vapors from being released into the atmosphere. It does this by trapping the vapors in a charcoal-filled canister so they can be drawn into the engine and burned later when the engine is running. If you continue filling the tank beyond the normal "click-off" point you can overload the system with vapors. This can cause the engine to run "too rich" and could eventually ruin the charcoal canister."

And you will get slobber marks on your 1/4 panel which looks disgusting.

ALMOST all 1998 & later MB's have OBVR (on-board vapor recovery) systems & if you try to keep filling after the nozzle clicks you CAN & will do damage to that system. ALSO you might get a fuel bath when removing the nozzle! HAVE seen several collasped fuel tanks from this! Don't overfill these models!!

Thanks Doc.I've seen a of lot people
overfill their gas tank esp.when gas
prices goes down. :)