Anyone with a 300SDL...
 

What color is the ACC check valve? It should be on the forward firewall ahead of the brake master cylinder. A line from the vacuum pump hits the forward firewall, goes into the check valve that's clipped to the firewall, then splits into a line that goes into the cabin and a line that goes to a vacuum reservoir. At least that's what the manual says. I just noticed that there's no check valve in my SDL, just a connecting bit of rubber tube. For that matter, I don't see the line that goes to the reservoir.

The check valve in my 91 300SE is yellow. I'm wondering if the SDL uses the same kind of check valve so I can widen my search.

The silly thing is that it's probably a $2.00 item at the dealer and I'll pay $5.00 for it at a scrap yard :)

Thanks,
Sixto
91 300SE
87 300SDL
83 300SD

Sixto:

They are all the same. You can use an aftermarket one from the autoparts store, too.

Check to see if the line for the reservior got broken off somewhere, too, behind something.

Peter