Air And Fuel Systems - Check; Valve Train And Head Assembly - Dodge D250 1990 Service Manual

In-Chassis Diagnostic Procedures
Page9E-2
Base Engine Components
DODGE Turbo Diesel
Air and Fuel Systems - Check
When diagnosing a low power problem, first troubleshoot the
air and fuel systems to make sure the engine is receiving
adequate intake air and fuel.
Valve Train and Head Assembly
The sound emitted from the overhead can indicate a valve train
problem. Loose rocker levers will clatter. A squeaking noise
can mean lack of lubrication for adjusting screw and the push
rod socket.