Save yourself a ton of time and go get a mitivac. You have to have one if you own a diesel mercedes. Use that to find your vacuum leak.

__________________
1979 240d 216k (W123) Daily Driver
Volvo 245DL 210k

1979 300D FOR SALE
2002 Tahoe 91k FOR SALE

1980 300sd 177k (W116) Sold
1980 300sd Parts (W116) Junked
1979 240D 121k (W123) Sold
1982 300TDT 298K (W123) (Sold)