The car will not shut off unless I do it manually by raising the hood and pressing the "STOP" lever?

Welsome to the forum, Mike. Use the search. IP shutoff valve, vac leak, etc.

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1989 300E 144K

Your heat issue and this are 99% likely to be related.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

go to your parts store and buy a miti vac...then you can figure out where your problems are.

For a quick fix...look for a four way connector that has the heat, door locks and other stuff attached to it and plug up the lines. Take the brown line and hook it up directly to the main vacuum line. Unless your fuel shut off valve is bad, this should shut your car off for now.

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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)