Monte Carlo V6-260 4.3L DSL (1983)
Piston: All Technical Service Bulletins
Diesel Engine - Rapping or Knocking Noise
Number:
84-46
Section:
6A (VI)
Date:
Feb., 1984
Subject:
RAPPING OR KNOCKING NOISE ON
5.7L OR 4.3L DIESEL ENGINES
Model and Year:
1982-84 CAPRICE, IMPALA, MALIBU, MONTE CARLO, EL CAMINO AND CELEBRITY
TO:
ALL CHEVROLET DEALERS LISTS
This bulletin cancels and replaces Chevrolet Dealer Service Bulletin 84-46 dated December, 1983. Previous copies should be destroyed. This new issue
includes three (3) illustrations and an improvement in diagnostics.
The 1982-84 V8 and V6 diesel engines have the piston pin moved .045 inches off center of the piston. This change was made to reduce the noise level of
the engine. If this offset is on the wrong side, a rapping or knocking noise will be heard as the engine warms up. It is possible to locate the cylinder by
loosening fuel lines to the nozzles. The noise level will be reduced.
There are two (2) ways that the piston offset could be on the wrong side:
1.
The piston could be installed backwards.
2.
The piston could be mismachined.
Piston - Correct Machining
To determine which of the above two (2) conditions may have occurred, refer to the illustrations. The cast notch in the top of the piston should be toward
the front of the engine. If the cast notch is properly located, then the piston should be removed from the engine and inspected. If the piston is incorrectly
machined, it will have an uneven chamfer as shown in the illustrations. A correctly machined piston will have an even amount of chamfer in the pin boss
area as shown in the illustrations.
