Part 1
ROCKER ARMS AND CAMSHAFT
Removal
Follow removal steps outlined in illustration.
Removal Service Point
[A] Rocker Arm, Shaft And Bearing Cap Removal.
(1) Install the special tools to the rocker arm to hold the lash adjuster.
(2) Loosen the camshaft bearing cap bolt. Do not remove the bolts from the cap.
(3) Remove the rocker arm, shaft and bearing cap as an assembly.
Installation
Installation in reverse order as removal.
Installation Service Points
]A[ Camshaft Installation.
(1) Turn the crankshaft to bring No.1 cylinder to the top dead center.
(2) Check that the rocker arm is installed correctly on the lash adjuster and valve.
(3) Install the camshaft while noting the identification mark (stamped on the hexagon section).
(4) Install the camshafts with their dowel pins positioned as shown in the illustration.
]B[ Rocker Arm Shaft Installation.
(1) Install the rocker arm shafts "A" and "B" to the camshaft bearing cap No.1 and insert the bolts into the holes of the bearing cap and shafts.
(2) Install the rocker arm shafts with the notched side facing the bearing cap No.1 and the oil grooved side facing downward. The shaft with a smaller oil hole is the rocker arm shaft "B".
]C[ Rocker Arm And Rocker Arm Shaft Installation.
(1) Insert the lash adjuster to rocker arm, being careful not to spill the diesel fuel. Then use the special tool to prevent the adjuster from falling while installing it. Apply a minimum amount of the specified sealant on the four places of the cylinder head.
NOTE: Be sure the sealing agent does not swell out onto the cam journal surface of the cylinder head. If it swells out, immediately wipe it off before it can dry.
Specified sealant:
3M NUT Locking No. 4171 or equivalent.
(3) Install the rocker arms, shafts and bearing caps such that the arrow mark on the bearing cap faces in the same direction as the arrow mark on the cylinder head.
(4) Tighten the bearing cap bolts to the specified torque.
(5) Remove the special tools from all rocker arms.
]D[ Bearing Cap Installation.
(1) Install the bearing caps according to the identification mark and cap number. No.2, 3 and 4 bearing caps bear the front mark. Install these caps with the front mark directed in the same direction as that on the cylinder head.
Identification mark:
[Intake] I
[Exhaust] E
(2) Gradually tighten the bearing caps in two or three steps. In the final step, tighten to the specified torque.
]E[ Camshaft Oil Seal Installation.
]F[ Circular Packing Installation.
(1) Install a 1.3 to 1.5 mm (0.052 to 0.059 inch) thick spacer to the special tool and drive in the circular packing.
NOTE: Use of MD724328 spacer for transmission is recommended.
CAUTION: The packing is overdriven if no spacer is fitted to the special tool.
]G[ Circular Packing Installation.
(1) Install the circular packing with the special tool.
]H[ Rocker Cover Installation.
(1) Apply specified sealant on the area specified in the illustration.
Specified sealant:
3M ATD Part No. 8660 or equivalent
Inspection
Rocker Arm Shaft
(1) Check the rocker arm mounting portions 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 is observed.
(3) Check the inside diameter and replace the rocker arm if damage or seizure is observed.
Camshaft
(1) Inspect the camshaft bearing journals for damage and binding. If the journals are binding, also check the cylinder head for damage. Also check the cylinder head oil holes for clogging.
(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 defective. Also measure the cam height and replace if out of limit.
Lash Adjuster Leak Down Test
CAUTION:
1. The lash adjuster is a precision part. Keep it free from dust and other foreign matters.
2. Do not disassemble the lash adjusters.
3. When cleaning the lash adjusters, use clean diesel fuel.
(1) Immerse the lash adjuster in clean diesel fuel.
(2) While lightly pushing down the inner steel ball using the special tool, move the plunger up and down four or five times to bleed air.
Use of the retainer facilitates the air bleeding of the rocker arm mounted type lash adjuster.
(3) Remove the special tool and press the plunger. If the plunger is hard to push in, the lash adjuster is normal. If the plunger can be readily pushed in all the way, bleed the lash adjuster again and test again. If the plunger is still loose, replace the lash adjuster.
CAUTION: Upon completion of air bleeding, hold the lash adjuster upright to prevent the inside diesel fuel from spilling.
(4) After air bleeding, set the lash adjuster on the special tool (Leak down tester MD998440).
(5) After the plunger has gone down somewhat 0.2 - 0.5 mm (0.008 - 0.020 inch), measure the time taken for it to go down 1 mm (0.04 inch). Replace if the measured time is out of specification.
Standard value:
4 - 20 seconds; /1 mm (0.04 inch)
[Diesel fuel at 15 - 20° C (50 - 68° F)]
CYLINDER HEAD AND VALVES
Removal
Follow removal steps outlined in illustration.
Removal Service Points
Precaution For Removed Parts
[A] Cylinder Head Bolt Removal.
(1) Keep removed parts in order according to the cylinder number and intake/exhaust.
[B] Retainer Lock Removal.
(1) Using the special tool, compress the spring.
(2) Remove the retainer locks.
[C] Valve Stem Seal Removal.
(1) Do not reuse removed valve stem seals.
Installation
Installation in reverse order as removal.
Installation Service Points
]A[ Valve Stem Seal Installation.
(1) Install the valve spring seat.
(2) Using the special tool, install a new stem seal to the valve guide.
CAUTION:
(1) Do not reuse removed valve stem seals.
(2) Always use the special tool to install the valve stem seal. Improperly installed valve stem seal may cause oil down.
]B[ Valve Spring Installation.
(1) Direct the valve spring end with identification color toward the spring retainer.
]C[ Retainer Lock Installation.
(1) Using the special tool, compress the valve spring and insert the retainer locks into position.
]D[ Cylinder Head Gasket Identification.
CAUTION: Do not apply sealant to the cylinder head gasket.
Identification mark:
72S2[SOHC]
72D4[DOHC]
]E[ Cylinder Head Bolt Installation.
(1) Tighten the cylinder head bolts in the sequence shown. Each bolt should be tightened in two to three steps, torquing progressively. Tighten to the specified torque in the final sequence.
CAUTION: Attach the head bolt washer in the direction shown in the figure.
(1) Tighten the bolts in two to three stages in the illustrated sequence.
(2) Back off the bolts once and tighten them to the specified torque in the same procedure as shown in step (1).
CAUTION: Attach the head bolt washer in the direction shown in the figure.
Inspection
Cylinder Head
(1) Check the cylinder head gasket surface for flatness by using a straightedge in the directions of A through G shown in the illustration.
(2) If the service limit is exceeded, correct to meet the specification.
Grinding limit: *0.2 mm (0.008 inch)
* Total resurfacing depth of both cylinder head and cylinder block.
Valve
(1) If the valve stem is worn (ridge wear) or otherwise damaged, replace. Also replace the valve if the stem end has a dent.
(2) Check the valve face for correct contact. If incorrect, reface using a valve refacer. Valve should make a uniform contact with the seat at the center of valve face.
(3) If the margin exceeds the service limit, replace the valve.
(4) Measure the overall length of the valve. If the specified limit is exceeded, replace the valve.
Valve Springs
(1) Measure the free height of the spring and, if it is smaller than the limit, replace.
(2) Measure the squareness of the spring and, if the limit is exceeded, replace.
Valve Guides
(1) Measure the clearance between the valve guide and valve stem. If the limit is exceeded, replace the valve guide or valve, or both.
Valve Seat
(1) Assemble the valve, then measure the valve stem projection between the end of the valve stem and the spring seating surface. If the measurement exceeds the specified limit, replace the valve seat.
Valve Seat Reconditioning Procedure
(1) Before correcting the valve seat, check for clearance between the valve guide and valve and, if necessary, replace the valve guide.
(2) Using the special tool or seat grinder, correct to obtain the specified seat width and angle.
(3) After correcting the valve seat, lap the valve and valve seat using lapping compound. Then, check the valve stem projection.
Valve Seat Replacement Procedure
(1) Cut the valve seat to be replaced from the inside to thin the wall thickness. Then, remove the valve seat.
(2) Rebore the valve seat hole in the cylinder head to a selected oversize valve seat diameter.
(3) Before fitting the valve seat, either heat the cylinder head up to approximately 250° C (482° F) or cool the valve seat in liquid nitrogen, to prevent the cylinder head bore from galling.
(4) Using a valve seat cutter, correct the valve seat to the specified width and angle.
Valve Guide Replacement Procedure
(1) Remove the snap ring from the exhaust valve guide[SOHC]
(2) Using a press, remove the valve guide toward the cylinder block.
(3) Rebore the valve guide hole of the cylinder head so that it fits the press-fitted oversize valve guide.
CAUTION: Do not install a valve guide of the same size again.
(4) Install the new snap ring into groove of exhaust valve guide.
(5) Press-fit the valve guide until it protrudes 14.6 mm (0.57 inch)[SOHC] 17.5 mm (0.69 inch) [DOHC] from the cylinder head top surface as shown in the illustration.
NOTE:
(1) When press-fitting the valve guide, work from the cylinder head top surface.
(2) Pay attention to the difference in length of the valve guides. [intake side: 44.0 mm (1.73 inch); exhaust side:48.0 mm (1.89 inch)] [SOHC] [intake side: 45.5 mm (1.79 inch); exhaust side: 50.5 trim (1.99 inch)] [DOHC]
(3) After installing the valve guides, insert new valves in them to check for sliding condition.