I already did a "purge valve" search, but none of the post explained what it does.
Here was my situation. Have 96 E320. About 6 weeks ago, I noticed that when I opened up fuel tank to fill it up, there seemed to be a noticeable "whoosh" of air (like what you sometimes get in really HOT weather). Then a few weeks later, I began to hear a noise toward the rear of the car (at least that was where it sounded like) as if you pushed your fist into a sheet of metal and then released it real quick. I thought that maybe the gas tank had some sort of expansion and then a "de-expansion".
I also considered it might be something moving around in the trunk and removed loose items (CD containers and some tools on right side holder area). Still heard noise.
Also seemed like there was always the woosh in the gas tank when I filled it AND I never seemed to be able to fill it to 1/1.
Was getting ready to call dealer when by pure "luck" the day before I planed to call the "Engine Check Light" came on and it said "Engine Electronics". Took it to delaer next day and they found that the Purge Valve needed to be replaced. Had them check under the car--nothing.
They drove it 20 miles+ after replacement and heard no noise.
I have drove it 250 miles so far after replacement and no noise has been heard.
Whoosh noise from gas tank is no more either now.
What does the purge valve do? How might it have related to this noise? I've looked at the diagrams on the W210 1996 manual and see where it is located but can't figure out what the purpose is and how it may have been related to that noise.
Am I being stupid here--does it purge air from fuel system???
- Jon E320 210.055
77 Mustang 307,000 mi
63 T-Bird [fully restored]