Mercedes: mercedes diesel, diesel mercedes, air control valve

Question
i am looking to buy a 1984 diesel mercedes owner says run well while driving until suddenly will quit in middle of road he thinks a bad injector. wut do u think could it be major fix.

Answer
Gary,
There seems to be a disconnect with the air control valve. A diesel is stopped by choking of the air.
Look for a defective shutoff control.
It may be vacuum controlled or electric. I do not know.
If the vehicle runs smooth and strong, I would not first suspect an injector.
Make sure that the fuel separator and filter have been changed recently. An injection cleaner would not hurt either.
Does the vehicle restart instantly? If not here may be a problem with the fuel pump or the pump control relay.
Good Luck and let me know what you discover.
Rob