DESCRIPTION
The cylinder head, Fig. 2-1, is made of cast iron alloy with cast passages for water and exhaust gases. Drilled water holes at the bottom of the cylinder head match the water discharge holes in the liner. Cooling water is circulated through the head and is discharged through an elbow mounted on the side of the head mounting flange. Exhaust passages in the cylinder head line up with elbows in the crankcase, which conduct the exhaust gases through the water discharge manifold to the exhaust manifold.
A well is located in the center of the cylinder head for application of the unit fuel injector. To ensure correct positioning of the injector, a mating hole for the injector locating dowel is located in the head.

1. Remove exhaust valve springs using single valve spring compressor and adapter screwed into the head, or the multiple valve spring compressor, Fig. 2-3.SINGLEMULTIPLEFig. 2-3 - Compressing Valve Springs2. Compress the springs sufficiently to remove the valve locks and spring seats, and then remove the springs.3. After spring removal, the exhaust valves can be removed from the bottom of the head. NOTE: Valve springs can be removed and replaced without removing the cylinder head from the engine. If this is done, the piston must be at top center to prevent the valves from falling into the cylinder when the valve locks are removed

Seal all water passages in the head and apply 586 to 655 kPa (85 to 95 psi) air pressure to the passages. Immerse the head in water maintained at 71° C (160° F) for two minutes. Using this method, the leaks are easily detected and minor leaks are opened-up by the hot water for easy detection.
NOTE: When performing the cylinder head leak test, a scrap injector should be installed using an injector crab, spherical washer and nut. Torque nut to 81 ± 14 N-m (60 ± 10 ft-lbs) before immersion into the hot water.
Core plug leaks can usually be repaired by replacing the plug. Leaks caused by cracks, porosity, or dirt inclusion are cause for rejection.

DESCRIPTION
The long stein exhaust valves, Fig. 2-17, are fabricated from a forged nickel-chromium alloy steel head and a tip hardened steel stem by means of friction welding. Single bead valve locks hold the valve in a tapered spring seat. Precision valve guides ensure proper valve seating

DESCRIPTION
The valve bridge, Fig. 2-23, operates two exhaust valves from one rocker arm. A spring and spring seat are held on the valve bridge stem by a lock ring. The spring seat rests in a socket in the cylinder head and the spring applies pressure to maintain contact between the valve bridge and the rocker arm.
The hydraulic lash adjuster maintains zero lash between the end of the valve stem and the valve bridge. Lube oil flows from the rocker arm through a drilled passage in the valve bridge to the top of the lash adjuster, past the ball check, and into the body. When the rocker arm
depresses the valve bridge, a slight movement of the plunger in the lash adjuster seats the ball check, trapping the oil. Since the oil is practically in-compressible, further movement of the rocker arm causes the lash adjuster plunger to force open the exhaust valve.

DESCRIPTION
Three rocker arms, Fig. 2-29, are mounted on the cylinder head. Two rocker arms actuate the four exhaust valves, the third operates the injector. The rocker arms are operated directly by the camshaft through a cam follower roller mounted at the fork end of each rocker arm. The opposite end of each rocker arm has an adjusting screw and locknut for setting the injector timing and adjusting the hydraulic lash adjusters. The injector rocker arm, although similar in appearance to the exhaust rocker arm, is stronger than the exhaust rocker arm, and can be identified by the yoke at the cam follower end which is square-shaped on the injector rocker arm, but V-shaped on the exhaust rocker arm. Also, only the injector rocker arm has the machined notch for the overspeed trip. Injector and exhaust rocker arms are not interchangeable.
Lubricating oil is supplied to the cam follower assembly and the adjusting screw end through drilled passages in the rocker arm.