Vintage Cars: 1978 450sl, loud whistle, rubber gasket

Question
I have a loud whistle when i start the car it will go away after warm up or increasing the rpms. I thougt maybe an aux air valve but not sure if the 1978s had one or where its located any ideas

Answer
Sounds like a vacuum leak to me, check lines from air cleaner to rear vavle cover, also front valve cover line.  I would check all rubber lines (air/vacuum) for breaks. When things warm up they expand and close small leaks. Also check rubber gasket on air cleaner( goes over intake)
Make sure your belts are tight, not frayed. Have someone start the car and move hoses while you listen for a change in sound.  Careful of moving parts
Let me know if you find anything.
Happy Motoring
Ron