I need a tech with some experience with the Euro models. I have a 117.962 engine and pulled the throttle housing to make sure that no vacuum leaks where present.

I was surprised to find the bottom port on the throttle housing open. It is missing the extension tube and the port does not pass into the throttle body. It has a plug type device that diverts it back to open air. Manual shows the top port for EGR and bottom for Vacuum switch, which I don’t have. SO do I need this bottom port?

On the other side of the throttle housing the 3/2-way switch is missing. In my manual (US) it shows a mechanical/pneumatic switch over valve that connects to the warm-up compensator – lower chamber. The valve is responsible for full load enrichment via the warm-up compensator. Prior to 1981 the lower chamber was open to atmosphere.


1983 500SL 117.962 engine, 107.046 chassis, emissions CAT only.
Warm-up Compensator is Bosch 436 140 101. Manual 7.3-120 checking fuel pressure does not list my compensator.

Thank for help, advice, or assurance.

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1983 500SL Euro

There are many different styles of throttle bodys on different engines, even "euro" engines. The lower port is for manifold vacuum & not needed on many applications, including yours!

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Thanks DOC for the reassurance on the throttle port!

What about the mechanical switchover? Can I upgrade with another/better application?

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1983 500SL Euro