There is an adjustment of some type on top of the bell shaped housing, on top of the injection pump of my 78 240-D. I was wondering what it adjusts and how to adjust it.


Why does it need to be adjusted, you might ask? After reading in a repair manual that all diesel Mercedes ijection pumps have a filter that needs to be replaced. I attempted to replace the one in my 240. Misinformation + ignorance = ijection pump out of whack. The only thing I messed with is the screw and lock nut on top of the altitude compensater. Thanks in advance for any advice.

adjust for very light smoke under hard acceleration near 3000 rpms (just perceptible in rear view in full sunlight)with engine fully warm. Turn out for richer(more smoke) in for leaner (less smoke). This will get you very close to the proper setting that is truly done on a test stand. You should also make sure your valves are properly adjusted (cold only) and check for chain stretch.

Bob D.

Thanks for the advice Bob D. I am wondering how much this will affect the life of the engine if I don't adjust it just right. I guess if I get the mix too rich the excess diesel will thin the oil. Is that right?

Too rich and you'll have excess carbon build up unless you drive it hard most of the time. Too lean and you'll be down on power and you don't have much to spare.

Bob D.