To be honest, it doesn't sound like 4 qts is really enough. My '90 300E owners manual (do you have yours?), on pg 114, lists 7.7 qts as an initial fill and 6.6 qts. as a fluid change.
More to the point, why don't you check your dipstick? Note, howevere, that the level showing on the dipstick is very temperature dependent. If the transmission is fully warmed up, make sure the fluid is between the minimum and maximum marks -- never, never overfill. But if the transmission is completely cooled off, the level, when actually being the MAXIMUM amount, will appear on the dipstick to be 10mm (0.4") below the MINIMUM mark on the stick [this information is from pg 79 of my owner's manual].
Hope this helped.