Engine - Rear Main Oil Leak Diagnostics
87chevy20Number: 88-59-6A
Section: 6A
Date: Oct., 1987
Subject: REAR MAIN OIL LEAK DIAGNOSIS
Model and Year: 1987 CAPRICE, MONTE CARLO, EL CAMINO
WITH 4.3L (CODE Z) ENGINE 1987 R, V, G, M TRUCKS WITH 4.3L (CODE Z) ENGINE 1988 C, K TRUCKS WITH 4.3L (CODE Z) ENGINE
TO: ALL CHEVROLET DEALERS
Chevrolet Dealer Service Bulletin 88-10 (Section 6A) dated April 1987 is being cancelled and superseded. This bulletin deletes the inspection for crosshatch machining marks and provides specific criteria for crankshaft replacement and specific instructions for assembling rear main oil seal.
Some 1987 and 1988 passenger cars, trucks and 1988 C/K model trucks equipped with 4.3L engines with engine build date codes prior to T1202 may experience a rear main oil seal leak condition due to a poor surface finish on the crankshaft sealing surface.
To diagnose this condition check the oil leak using an ultraviolet light and engine oil dye. If all of the following conditions are met replace the crankshaft and rear main oil seal.
1. Leakage is between the crankshaft sealing surface and crankshaft oil seal lip.
2. Engine build code is prior to T1202. (See explanation below).
3. Removal and inspection of the rear main oil seal indicates the seal is not torn.
If all of the above conditions are not met, replace only the rear main oil seal and retainer.
NOTICE: THE ASSEMBLY OF THE REAR MAIN OIL SEAL AND RETAINER MUST BE PERFORMED IN THE FOLLOWING SEQUENCE OR POTENTIAL FOR AN OIL LEAK AT THE REAR MAIN OIL SEAL EXISTS.
1. LOOSEN OIL PAN FASTENERS AND ALLOW OIL PAN AND AND OIL PAN SEAL TO FALL FREE OR REAR MAIN OIL SEAL RETAINER.
2. INSTALL NEW REAR MAIN OIL SEAL AND RETAINER. TORQUE RETAINER FASTENERS TO SPECIFICATION.
3. AFTER TORQUING RETAINER FASTENERS, TORQUE OIL PAN FASTENERS TO SPECIFICATION.
IF THIS PROCEDURE IS NOT FOLLOWED THE OIL PAN MAY INTERFERE WITH THE RETAINER AND NOT ALLOW THE REAR MAIN OIL SEAL TO CENTER ON THE CRANKSHAFT.
FIGURE 1:
Engine build code determination - Engine date code location is shown in Figure 1. The build date codes may be found in this area and appear as shown in the following example:
T1202ABC
The first letter indicates the plant where the engine was manufactured. The next four numbers indicate the day of manufacture; in this case 12th month 2nd day, and the last three digits may be any broadcast code.