Greetings Forumites!
Can someone describe to me the purpose of the two throttle-actuated vacuum valves/switches which are mounted on top of the camshaft cover of my 1983 300TD?

In troubleshooting my recent tranny and vacuum problems, I discovered that the actuating fingers for these two valves were worn away to nothing. Approximately $3.00 and ten minutes labor later, two new fingers were installed. I'm not sure if it's psychological but, the driveability of Marlene seems to have noticeably improved.

In particular, acceleration from a dead stop feels like it is more consistent.

I'm just guessing but, do they control the waste gate operation?

Cheers,
Randy

The waste gate guess was close. They control the egr in it's relation to the throttle setting. They have to do with pollution controls and shifting.

They are part of a pneumatic control system the likes of which were used to control steam boilers a long, long time ago.

__________________
Jim

Vielen Dank!

R

The two "vacuum switchover valves" on top of the valve cover are actuated by a cam lever. They regulate vacuum to BOTH the EGR system and Transmission vacuum modulator through the vacuum valve which sits on the Injection Pump.

I just replaced both of these on my '82 240D which were leaking profusely and it helped to bring my transmission shifting back to normal.

If you are having similar problems, just search this forum for "transmission shifting" etc.

Regards,
Jack