S/T Truck (With or Without Air Conditioning)

1. Disconnect battery cable.

2. Drain engine of all coolant. Use a clean container and save the coolant for re-use.

3. Loosen generator adjustment bolts.

4. Remove generator belt.

5. Remove generator adjustment bolts.

6. Disconnect throttle cable at the intake manifold.

7. Remove generator adjustment pivot bracket and lay generator aside.

8. Disconnect coolant sensor wire.
9. Disconnect hose at thermostat housing.

10. Disconnect strut rod bracket at generator front bracket.

11. Remove generator front bracket.

12. Disconnect electrical harness at thermostat.

ITEMS 13 THROUGH 18 APPLY TO TRUCKS EQUIPPED WITH AIR CONDITIONING.

13. Disconnect electrical harness at air conditioning compressor.

14. Remove air conditioning compressor belt.

15. Remove air conditioning compressor bracket.

16. Disconnect air conditioning compressor harness.

17. Remove air conditioning compressor from bracketry and lay aside.

18. Remove air conditioning compressor front support bracket.

19. Disconnect upper radiator hose at thermostat housing.

20. Remove vacuum line bracket from thermostat housing.

21. Remove thermostat housing.

2.5L L4 CYLINDER HEADBLOCKED COOLANT PASSAGES:

# 22. Insert the probe into the two cooling passages (see Illustration). The probe is to be inserted a minimum of 3.5 inches into the right (passenger side) coolant passage and 4.5 inches into the left (driver side) coolant passage. If this can be done no further action is required. Proceed to step 23. If the probe will not slide into one or both passages even after several attempts, the cylinder head must be replaced. Refer to S/T Truck Service Manual, ST-369-86, Section 6A1 for removal and installation procedures, then proceed to step 23.
23. Clean the thermostat housing and cylinder head of all old sealant.

24. Apply sealant GM P/N 1052915 or equivalent to the thermostat housing and install to the cylinder head.

25. Reverse steps 1-21 for parts re-installation. Refill cooling system using original coolant. Top off coolant with GM P/N 1052753 or equivalent mixed 50% with water.

26. Install Campaign Identification Label according to instructions contained in this bulletin.


# Denotes change
SPECIFICATIONS:

W/A/C W/O A/C

Belt tension (old belts):

Generator 400 N (90 lbs) 300 N (67 lbs)
Air conditioning 400 N (90 lbs)

Thermostat Housing Bolts: 27 N-m (20 ft.lbs) 27 N-m (20 ft.lbs)

Generator Mounting torque:

Rear Bolt 27 N-m (20 ft.lbs) 27 N-m (20 ft.lbs)
Lower Mounting Bolt 50 N-m (37 ft.lbs) 50 N-m (37 ft.lbs)
Adjusting Arm Bolt 27 N-m (20 ft.lbs) 27 N-m (20 ft.lbs)

Compressor Mounting Bolts:

Front 43 N-m (32 ft.lbs)
Rear 30 N-m (22 ft.lbs)