NEW HEAD BOLT TORQUING PROCEDURE

NEW HEAD BOLT TORQUING PROCEDURE-

VEHICLES AFFECTED: 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.

Service Procedures

2.5L L4 ENGINES ---------------

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 992545, or equivalent to threaded portion of bolt Number 9.

4. Install all bolts and torque in sequence (See Figure No. 1) to 25 Nm (18 lb ft).

5. Retorque bolts 1, 2, 3, 4, 5, 6, 7, 8 and 10 to 35 Nm (27 lb ft). Retorque bolt 9 to 25 Nm (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 1.

7. Following the same sequence, tighten all bolts an additional 90 degrees (1/4 turn).

2.8L V6 ENGINE --------------

1. Install cylinder head using a new gasket.

2. Clean all bolts.

3. Apply sealer, P/N 992545, or equivalent to the threaded portion of bolts.

4. Install bolts and torque in sequence (See Figure No. 2) to 55 Nm (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 2.

6. Using the same sequence, tighten bolts an additional 90 degrees (1/4 turn).

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.