Engine - Increased Noise

89chevy13

GMC NUMBER: 89-T-23


GROUP: 6E - Engine Emission

DATE: February, 1989

CORPORATE
NUMBER: 836606R
SUBJECT: INCREASED ENGINE NOISE

MODELS: 1988 C/K/R AND EARLY BUILT 1989 C/K/R TRUCKS W/7.4L (VIN CODE N) ENGINE
Some 1988 C, K, R and early built 1989 C, K and R trucks with 7.4L engine and serpentine drive may receive customer comments of increased engine noise. When investigating this condition, a check of the Air Injection Reaction (A.I.R.) injection valve adapter tube should be made. A broken or cracked adapter tube could account for a noise condition. A new adapter with a support tab, P/N 10129509 is now available and may be used with a rework of the A/C compressor A.I.R. pump mounting bracket. Parts are currently available from GMSPO.

Figure No. 1:

Service Procedure: (See Illustration)

1. Remove old adapter.

2. Temporarily install new adapter to determine hole location for support tab.

3. On trucks with air conditioning, remove compressor from mounting bracket and lay aside. DO NOT DISCHARGE REFRIGERANT FROM SYSTEM.
4. On tracks without air conditioning, remove idler pulley bracket and save for reinstallation.

5. Scribe location of the support tab on A/C compressor/A.I.R. pump bracket.

6. Drill 5/16" hole in bracket.

7. Install new adapter, and attach support tab to bracket using 11509589 bolt, 9439511 washer, and 11508279 nut. Torque to 20-27 N-m. (14- 20 lbs./ft.).

8. Reinstall A/C compressor and/or idler pulley bracket.

For vehicles under warranty, use:

Labor Operation Number: T7840
Labor Time: .6 Hr