K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Camshaft Gear/Sprocket: Service and Repair
The timing chain on these engines has an allowable deflection of up to 0.80 inch. However, if timing chain deflection exceeds 0.80 inch, due to
component wear or chain stretch, the engine may experience rough idle, low power, poor fuel economy and/or excessive emission of white
smoke. It is recommended that timing chain deflection be measured whenever the front cover is removed, and any time the above symptoms
cannot be traced to a fuel system malfunction. To check timing chain deflection, proceed as follows:
Remove front cover as outlined.
Mount a dial indicator on left front of block positioning indicator so that plunger contacts timing chain at the midpoint between the two timing
Press timing chain outward (parallel to front face engine block), as far as possible by hand, then zero indicator.
Press chain inward as far as possible, then read deflection from dial indicator.
Deflection should not exceed 0.80 inch for used chain or 0.50 inch for new chain.
If deflection is excessive, replace chain and/or timing gears as needed.