Never gave it a thought because I thought it was normal to hear a whoosh when the fuel filler cap is opened even to the first detent, given that the fuel system operates under pressure. Then read a post in another MB forum where the owner mentioned hearing such a noise for the very first time on his SL500. Does the whoosh suggest I've got an evaporative emissions problem on my W124, or is typical to get a pressure release after the vehicle has been driven for a while just prior to fueling? Would weather conditions play a role (Florida vs Minnesota)?

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

My 300E always does that....and seems to have no issues running, so I'm not worried.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

My 300E and e320 both whoosh when the gas cap is opened and always have. ithink its normal.