Rocker Arm Assembly: Service and Repair
REMOVAL SERVICE POINT
ROCKER ARM AND ROCKER ARM SHAFT REMOVAL
Caution: If the lash adjuster is re-used, clean the lash adjuster.
(1) Set special tool MD998443 to prevent the lash adjuster coming free and falling to the floor.
INSTALLATION SERVICE POINTS
>A<CAMSHAFT INSTALLATION
(1) Apply engine oil to the camshaft journals and cams, and then install the camshafts.
Use care to prevent confusion of the right and left bank camshafts.
NOTE: The right bank camshaft is identified by a slit 4 mm (0.157 inches) wide at the rear end of the camshaft.
(2) Check to see that the dowel pin of the camshaft is located at the position shown.
>B< LASH ADJUSTER INSTALLATION
Caution: If the lash adjuster is re-used, clean the lash adjuster.
(1) Fit the lash adjuster onto the rocker arm without allowing diesel fuel to spill out. Fit special tool MD998443 to prevent the lash adjuster coming free and falling to the floor.
>C
(1) Temporarily tighten the rocker shaft with bolts at the condition that all the intake valve rocker arms do not push the valves.
(2) Insert the rocker shaft spring from above and mount it at right angles to the plug guide.
NOTE: Before installing the exhaust rocker arms and rocker arm shaft, mount the rocker shaft spring.
(3) Remove the special tools used to hold the lash adjusters in position.
(4) Check ensure that the flat side of the rocker shaft is directed as shown in the illustration.
>D<CAMSHAFT OIL SEAL INSTALLATION
INSPECTION
CAMSHAFT
Measure cam height (longer diameter of the cam). If it exceeds the limit, replace the camshaft.
Standard value:
Intake side 37.58 mm (1.4795 inches)
Exhaust side 36.95 mm (1.4547 inches)
Limit:
Intake side 37.08 mm (1.4598 inches)
Exhaust side 36.45 mm (1.4350 inches)
LASH ADJUSTERS
Caution:
1. The lash adjusters are precision-engineered mechanisms. Do not allow them to become contaminated by dirt or other foreign substances.
2. Do not attempt to disassemble the lash adjuster.
3. Use only fresh diesel fuel to clean the lash adjusters.
(1) Prepare three containers and approximately 5 dm (3) (30.5 quart) of diesel fuel. Into each container, pour enough diesel fuel to completely cover a lash adjuster when it is standing upright. Then, perform the following steps with each lash adjuster.
(2) Place the lash adjuster in container A and clean its outside surface.
NOTE: Use a nylon brush if deposits are hard to remove.
(3) While gently pushing down the internal steel ball using wire [0.5 mm (0.020 inches) diameter] or special tool MD998442, move the plunger through 5 to 10 strokes until it slides smoothly. In addition to eliminating stiffness in the plunger, this operation will remove dirty oil.
Caution: The steel ball spring is extremely weak, so the lash adjuster's functionality may be lost if the air bleed wire is pushed in hard.
NOTE: If the plunger remains stiff or the mechanism appears otherwise abnormal, replace the lash adjuster.
(4) Remove the lash adjuster from the container. Then, push down the steel ball gently and push the plunger to eliminate diesel fuel from the pressure chamber.
(5) Place the lash adjuster in container B. Then, gently push down the internal steel ball using wire [0.5 mm (0.020 inches) diameter] or special tool MD998442 and move the plunger through 5 to 10 strokes until it slides smoothly. This operation will clean the lash adjuster's pressure chamber.
Caution: The steel ball spring is extremely weak, so the lash adjuster's functionality may be lost if the air bleed wire is pushed in hard.
(6) Remove the lash adjuster from the container. Then, push down the steel ball gently and push the plunger to eliminate diesel fuel from the pressure chamber.
(7) Place the lash adjuster in container C. Then, gently push down the internal steel ball using wire [0.5 mm (0.020 inches) diameter] or special tool MD998442.
Caution: Do not use container C for cleaning. If cleaning is performed in container C, foreign matter could enter the pressure chamber when the chamber is filled with diesel fuel.
(8) Stand the lash adjuster with its plunger at the top, then push the plunger downward firmly until it moves through its greatest possible stroke. Return the plunder slowly, then release the steel ball and allow the pressure chamber to fill with diesel fuel.
(9) Remove the lash adjuster from the container, then stand the lash adjuster with its plunger at the top. Push the plunger firmly and check that it does not move.
NOTE: If lash adjuster contracts, perform the operations (7) through (9) again to fill it with diesel fuel completely. Replace the lash adjuster if it still contracts after performing these steps.
(10) Stand the lash adjuster upright to prevent diesel fuel spilling out. Do not allow the lash adjuster to become contaminated by dirt or other foreign matter. Fit the lash adjuster onto the engine as soon as possible.