Engine - Revised Cylinder Head Installation
File In Section: 6 - EngineBulletin No.: 77-61-14
Date: October, 1997
SERVICE MANUAL UPDATE
Subject:
Section 6 - Engine Mechanical - Cylinder Head Installation
Models:
1992-97 C, K, G, and P Trucks
with 6.5L Diesel Engines (VINs P, S, V, F - RPOs L49, L56, L57, L65, L65-CMT)
The cylinder head torquing sequence has been revised. The new procedure incorporates torque angle in the final tightening sequence, similar to the current crankshaft and bearings installation procedure. For all model years of the 6.5L engine, use the information provided in this bulletin. This information is also available in the 1998 Service Manual.
Cylinder Head Installation
Important:
^ Make sure that the block gasket surfaces are clean.
^ The head gasket material is soft. Handle the gasket with care. Make sure the gasket surface is not creased or dented.
^ Do not use a sealer on the Head Gasket. The head gasket is made with sealant on the gasket surface. Additional sealer may cause leakage or malfunction. In addition, some sealers may attack the initial sealant on the gasket (See Figure 1).
1. Install the cylinder head gaskets to the block, over the cylinder head dowel pins.
Cylinder Head Bolt Tightening Sequence:
2. Install the cylinder heads to the block, over the cylinder head gaskets and the cylinder head dowel pins (See Figure 2).
3. Apply thread sealant GM P/N 12345382 or equivalent, to the bolt threads and under the bolt heads.
Fastener Notice
Notice:
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
4. Install the cylinder head bolts using the installation and tightening sequence shown in Figure 2.
Tighten
^ In sequence (Figure 2), tighten all of the cylinder head bolts to 25 N.m (20 lb ft).
^ In sequence (Figure 2), tighten all of the cylinder head bolts to 75 N.m (55 lb ft).
^ In sequence (Figure 2), retighten all of the cylinder head bolts to 75 N.m (55 lb ft).
^ In sequence (Figure 2), tighten all of the cylinder head bolts and additional 90 degrees - 100 degrees (1/4 plus turn).