Diesel Engines Cylinder Head Assembly

The manufacturer’s manual provides detailed assembly instructions but includes little about the things that can go wrong. Most assembly errors can be categorized as follows:

• Insufficient lubrication. Heavily oil sliding and reciprocating parts, lightly oil head bolts and other fasteners, except those that penetrate into the water jacket. These fasteners should be sealed with Permatex No. 2 or the high-tech equivalent.
• Reversed orientation. Most head gaskets, many head bolt washers, and all thermostats are asymmetrical.
• Mechanical damage. Run fasteners down in approved torque sequences and in three steps—1/2, 2/3, and 1/1 torque (Fig. 7-39). Exceptions are torque-to-yield head bolts and rocker arm shaft fasteners. The former are torqued as indicated by the manufacturer, whose instructions will be quite explicit. The latter— rocker shaft fasteners—should be brought down in very small increments, working from the center bolts out.

Gaskets, especially head gaskets, might also be damaged during assembly. Lower the head on a pair of guide pins lightly threaded into the block. Pins can be fashioned from discarded head bolts by cutting the heads off. If pins are too short to extend through the head casting, slot the ends for screwdriver purchase.

Set initial valve lash adjustments, bleed the fuel system, start the engine. Final lash adjustments are usually made hot, after the engine has run for 20 minutes or so on the initial settings (Fig. 7-40).

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