450sl cold start

[nonewname]

'74 450sl starts fine cold (below 40 degrees) but within a few seconds the idle begins to race between 1,000 and 3,000. Rapidly at first and gradually slows in durration and rpms. Any clues?
Thanks, Randy

[Deltacom]

Replace Auxiliary Air Valve

[cth350]

Also, see if there is any change in behavior if you disconnect the sensor in the horn of the air cleaner. -CTH

[jr811]

On my 1979 450SL it looks like the Auxiliary Air Value screws into the top of a metal housing. Does it take a special tool to remove this value?


Jim

[Deltacom]

There are two types of auxliary air valves. Flat top and domed top. They are held only by two 10mm screws.