Engine - Detonation When Warm
84-2596
SEPT., 1985
Subject: ENGINE DETONATION ON 5.0L L69 ENGINE
Model and Year: 1984 MONTE CARLO SS
TO: ALL CHEVROLET DEALERS
Customer comments of engine detonation may be received on 1984 Monte Carlo super sport vehicles equipped with 5.0L L69 engines. Some audible detonation is common vehicles equipped with knock sensor systems and can be expected when engines are cold, since the ESC system does not start functioning until the engine warms up. For vehicles that exhibit excessive or abnormal warmed up detonation, the following procedures are recommended:
1. Check and verify engine timing is set to specification.
2. Remove knock sensor, checking torque required to remove it. If removal torque is in excess of 30 ft.lbs., install a new sensor.
3. Check the removed sensor to make sure it is not distorted, bent, or damaged.
4. Wire brush the threads on the sensor and clean the threads in the engine block thoroughly.
5. Before reinstalling sensor, the threads must be painted with a sealer (GM P/N 9985000). The sensor should be installed to 12-16 ft.lbs.
In the event the above action does not correct the complaint, a service PROM with revised spark calibrations has been released. Refer to the following chart for correct usage:
New P/N Usage
1227178 1984 Federal L69 With 3-Speed Automatic
1227179 1984 California L69 With 3-Speed Automatic
Initial timing in all cases (before and after) is 6~ BTDC.