Well, plz forgive me for mixing stuff up but i'm very new at this game and yes it's the July 2013 patch that i have installed.
I tried some single missions with all the different F-4 variants B,C,D etc and none of them has sound for the engines.
Seems like its the only plane that misses it though after testing lots.
Was going trough the F-B_Data.ini and found this:
[sound]
EngineSoundName=J79
AfterburnerSoundName=J79Burner
DamagedEngineSoundName=
FlapsSoundName=Flaps
AirbrakesSoundName=Airbrakes
GearsSoundName=Gear
StallsoundName=StallSound
WindSoundName=kfirairflow
EngineSoundPosition=0.0,-3.64,0.00
Can't seem to find the soundfile named J79 though in the soundfolder in my MOD folder, maby this is the problem?