if you are working on your 240d it has a om616 engine. you need the mercedes engine manual that covers engines om615/616/617.91x
there is one on ebay right now for ~$50:

https://www.ebay.com/itm/MERCEDES-BENZ-ENGINES-OM-615-616-617-SERVICE-MANUAL-JUNE-1975-PRINTING/263428411331?hash=item3d558e8fc3:g:wmQAAOSwQN5aVW8c&vxp=mtr