Technotes - Engine Builder Magazine


Engine Builders: There has been some confusion about the proper method of push rod removal and installation for 1992-2000 GM 6.5L VIN F and S diesel engines, especially during re-assembly of valve train components, according to the AERA Technical Department.

Because the push rod design has different hardness requirements for each end, it is important that the installation of each push rod be properly done during assembly. The rocker arm end endures greater stresses, thus requiring increased hardness as compared to the other end.

Important: If the original push rods are being reused they must be installed in the same position as they were removed, due to the different degrees of hardness at each end. A paint stripe or copper coloring identifies the upper end of the push rod. If the paint stripe is no longer visible, mark the push rod on the upper end as the push rods are removed.

Aftermarket push rod tubes may not be marked in exactly this way, but each end should be visibly different than the other, with the upper end marked. Those tubes are also manufactured to acceptable hardness values on both ends.

  1. Install the valve pushrods with the copper-colored, painted or marked end upward.

  2. Install the valve rocker arm shaft assembly. NOTICE: Improper installation of the valve rocker arm shaft bolts may cause valve rocker arm shaft breakage and piston-to-valve contact.

  3. Install the bolts.

  4. Rotate the crankshaft clockwise (from the front), until the mark on the crankshaft balancer is at the 2 o’clock position.

  5. Rotate the crankshaft back counterclockwise 88 mm (3-1/2?), aligning the crankshaft balancer mark with the first lower water pump bolt, at approximately the 12:30 position.

  6. This procedure will position the engine components so that no valves are completely open and close to a piston crown.

  7. Install the rocker arm hold down bolts finger-tight.

  8. Alternately tighten the bolts to 40 ft/lbs (55 Nm).

  9. Rotate the crankshaft in order to make sure that there is free-movement of the valve train.

Engine Builders: AERA’s Technical Committee has issued a bulletin regarding proper bolt torque measurements for the intake manifold on 1998-2003 Isuzu 3.2L and 3.5L VIN V, X and W engines. These engines are found in Rodeos, Troopers and other vehicles.

This information applies only to the lower intake manifold bolts that attach to the engine’s cylinder heads.

To improve the durability of the intake manifold gasket, the lower intake mounting bolt torque has been reduced for this engine. Under testing, it has been determined that a lower torque value may extend the expected usefulness of the gasket. The correct mounting bolt torque is 13 ft.lbs. (18 Nm) for all 3.2L and 3.5L engines.

In addition to the reduced intake manifold mounting bolt torque value, the throttle body bolt torque has also been updated. Refer to Figure 1 for the correct torque according to the engine application.

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