Rocker Arms and Camshaft

REMOVAL AND INSTALLATION

REMOVAL SERVICE POINTS
[[A]] ROCKER ARMS AND SHAFT REMOVAL

CAUTION: If the lash adjuster is reused, clean the lash adjuster.





Set special tool MB998443 to prevent the lash adjuster coming free and falling to the floor.

INSTALLATION SERVICE POINTS
]]A[[ CAMSHAFT INSTALLATION

CAUTION: Use care to prevent confusion of the right and left bank camshafts.





1. Apply engine oil to the camshaft journals and cams and then install the camshafts.

NOTE: The right bank camshaft is identified by a slit 4 mm (0.16 inch) 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 reused, 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[[ ROCKER ARM, ROCKER ARM SHAFT AND ROCKER SHAFT SPRING INSTALLATION
1. Temporarily tighten the rocker shaft with bolts so that all the intake valve rocker arms do not push on the valves.
Tightening torque: 31 ± 3 Nm (23 ± 2 ft. lbs.)





2. Insert the rocker shaft spring from above and mount it at right angles to the plug guide.





3. Make sure that the notch of the rocker shaft is in the position shown in the illustration.

NOTE: Mount the rocker shaft spring before installing the exhaust rocker arms and rocker arm shaft.

]]D[[ CAMSHAFT OIL SEAL INSTALLATION








Use special tools MD998713 and MB991559 to install the camshaft oil seal.

INSPECTION
ROCKER ARM SHAFT
Check the rocker arm mounting areas of the rocker arm shafts for wear or damage. Replace as necessary.

ROCKER ARM





1. Check the roller surface and replace the rocker arm if recesses, damage or heat seizure is observed.
2. Check roller rotation and replace the rocker arm if uneven rotation or roller backlash of the roller is observed.
3. Check the inside diameter and replace the rocker arm if damage or seizure is observed.

CAMSHAFT
1. Check the camshaft bearing journals for damage and binding. If the journals are binding, check the cylinder head for damage. Also check the cylinder head for clogged oil holes.
2. Check the tooth surface of the distributor drive gear teeth of the camshaft and replace if abnormal wear is evident.





3. Check the cam surface for abnormal wear and damage and replace if necessary. Also measure the cam height and replace if out of minimum limit.
Standard value:
Intake 37.71 mm (1.485 inches)
Exhaust 37.14 mm (1.462 inches)
Minimum limit:
Intake 37.21 mm (1.465 inches)
Exhaust 36.64 mm (1.443 inches)

LASH ADJUSTERS

CAUTION
^ The lash adjusters are precision-engineered mechanisms. Do not allow them to become contaminated by dirt or other foreign substances.
^ Do not attempt to disassemble the lash adjusters.
^ Use only fresh diesel fuel to clean the lash adjusters.





1. Prepare three containers and approximately 5 dm3 (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.

CAUTION: The steel ball spring is extremely weak, so the lash adjuster's functionality may be lost If the air wire is pushed in hard.





3. While gently pushing down the internal steel ball using wire [0.5 mm (0.020 inch) in diameter] or special tool MD998442, move the plunger through five to ten strokes until it slides smoothly. In addition to eliminating stiffness in the plunger, this operation will remove dirty oil.

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.

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.





5. Place the lash adjuster in container B. Then, gently push down the internal steel ball using a wire [0.5 mm (0.020 inch) in diameter] or special tool MD998442 and move the plunger through five to ten strokes until it slides smoothly. This operation will clean the lash adjuster's pressure chamber.





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.

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.





7. Place the lash adjuster in container C. Then, gently push down the internal steel ball using a wire [0.5 mm (0.020 inch) in diameter] or special tool MD998442.





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 plunger 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 its plunger at the top. Push the plunger firmly and check that it does not move.

NOTE: If the lash adjuster contracts or moves, perform the operations (7) through (9) again to fill it with diesel fuel completely. Replace the lash adjuster if it still contracts or moves after performing these steps.

10. Stand the lash adjuster upright to prevent diesel fuel from 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.