Engine - Updated Head Bolt Torquing Procedure
87chevy19Number: 88-52
Section: 6A
Date: September, 1987
SUBJECT: NEW HEAD BOLT TORQUING PROCEDURE
MODELS: 1988 S/T WITH 2.5L( VIN CODE E) OR 2.8L (VIN CODE R) ENGINES
On 1988 S/T trucks with the 2.5L and 2.8L engines, the head bolt torquing has been changed to the Dynamic Torque (torque bolt to specified torque and then rotate bolts a specified distance) method. If it becomes necessary to remove and reinstall the cylinder head on 1988 S/T models equipped with these engines, the following procedures must be followed to ensure correct bolt installation.
FIGURE NO. 1 - 2.5L L4:
SERVICE PROCEDURES
2.5L L4 ENGINE
1. Install cylinder head using a new gasket.
2. Clean all bolts.
3. Coat threaded portion of bolts 1, 2, 3, 4, 5, 6, 7, 8 and 10 with engine oil. Apply sealant, P/N 1052080, or equivalent to threaded portion of bolt Number 9.
4. Install all bolts and torque in sequence (See Figure No. 1) to 25 N-m (18 lb. ft.).
5. Retorque bolts 1, 2, 3, 4, 5, 6, 7, 8 and 10 to 35 N-m (27 lb. ft.). Retorque bolt 9 to 25 N-m (18 lb. ft.).
6. Draw a line across the head of each bolt with a marking crayon to mark the position of each bolt, see Figure No. 1.
7. Following the same sequence, tighten all bolts an additional 90 degrees (1/4 turn).
FIGURE NO. 2 - 2.8L V6:
2.8L V6 ENGINE
1. Install cylinder head using a new gasket.
2. Clean all bolts.
3. Apply sealant, P/N 1052080, or equivalent to the threaded portion of bolts.
4. Install bolts and torque in sequence (see Figure No. 2) to 55 N-m (40 lb. ft.).
5. Draw a line across the head of each bolt with a marking crayon to mark the position of each bolt, see Figure No. 2.
6. Using the same sequence, tighten bolts an additional 90 degrees (1/4 turn).