SPRINGS-VALVE
DESCRIPTION
The valve springs are made from high strength chrome silicon steel. The springs are NOT common for intake and
exhaust applications. The exhaust spring has an external damper. The valve spring seat is integral with the valve
stem seal, which is a positive type seal to control lubrication.
REMOVAL
1. Remove the cylinder head cover (Refer to 9 - ENGINE/CYLINDER HEAD/CYLINDER HEAD COVER(S) -
REMOVAL).
2. Using Special Tool 8516 Valve Spring Compressor, remove the rocker armsand the hydraulic lash adjusters.
3. Remove the spark plug for the cylinder the valve spring and seal are to be removed from.
4. Apply shop air to the cylinder to hold the valves in place when the spring is removed.
NOTE: All six valve springs and seals are removed in the same manner; this procedure only covers one
valve seal and valve spring.
5. Using Special Tool 8387 Valve Spring Compressor, compress the valve spring.
NOTE: It may be necessary to tap the top of the valve spring to loosen the spring retainers locks enough to
be removed.
6. Remove the two spring retainer lock halves.
NOTE: the valve spring is under tension use care when releasing the valve spring compressor.
7. Remove the valve spring compressor.
NOTE: The valve springs are NOT common between intake and exhaust.
8. Remove the spring retainer, and the spring.
9. Remove the valve stem seal.
NOTE: The valve stem seals are common between intake and exhaust.
INSTALLATION
NOTE: All six valve springs and seals are removed in the same manner; this procedure only covers one
valve seal and valve spring.
1. Apply shop air to the cylinder to holdthevalvesinplacewhilethespringis installed.
NOTE: The valve stem seals are common between intake and exhaust.
2. Install the valve stem seal.
NOTE: The valve springs are NOT common between intake and exhaust.
3. Install the spring retainer, and the spring.
4. Using Special Tool 8387 Valve Spring Compressor, compress the valve spring.
5. Install the two spring retainer lock halves.
NOTE: the valve spring is under tension use care when releasing the valve spring compressor.
6. Remove the valve spring compressor.
7. Disconnect the shop air to the cylinder.
8. Install the spark plug for the cylinder the valve spring and seal was installed on.
SPRINGS - VALVE
DESCRIPTION
The valve springs are made from high strength chrome silicon steel. There are different springs for intake and
exhaust applications. The exhaust spring has an external damper. The valve spring seat is integral with the valve
stem seal, which is a positive type seal to control lubrication.
REMOVAL
1. Remove the cylinder head cover (Refer to 9 - ENGINE/CYLINDER HEAD/CYLINDER HEAD COVER(S) -
REMOVAL).
2. Using Special Tool 8516 Valve Spring Compressor, remove the rocker armsand the hydraulic lash adjusters.
3. Remove the spark plug for the cylinder the valve spring and seal are to be removed from.
4. Apply shop air to the cylinder to hold the valves in place when the spring is removed.
NOTE: All six valve springs and seals are removed in the same manner; this procedure only covers one
valve seal and valve spring.
5. Using Special Tool 8387 Valve Spring Compressor, compress the valve spring.
NOTE: It may be necessary to tap the top of the valve spring to loosen the spring retainers locks enough to
be removed.
6. Remove the two spring retainer lock halves.
NOTE: the valve spring is under tension use care when releasing the valve spring compressor.
7. Remove the valve spring compressor.
NOTE: The valve springs are NOT common between intake and exhaust.
8. Remove the spring retainer, and the spring.
9. Remove the valve stem seal.
NOTE: The valve stem seals are common between intake and exhaust.
INSTALLATION
NOTE: All six valve springs and seals are removed in the same manner; this procedure only covers one
valve seal and valve spring.
1. Apply shop air to the cylinder to holdthevalvesinplacewhilethespringis installed.
NOTE: The valve stem seals are common between intake and exhaust.
2. Install the valve stem seal.
NOTE: The valve springs are NOT common between intake and exhaust.
3. Install the spring retainer, and the spring.
4. Using Special Tool 8387 Valve Spring Compressor, compress the valve spring.
5. Install the two spring retainer lock halves.
NOTE: the valve spring is under tension use care when releasing the valve spring compressor.
6. Remove the valve spring compressor.
7. Disconnect the shop air to the cylinder.
8. Install the spark plug for the cylinder the valve spring and seal was installed on.
BEARINGS-CRANKSHAFT MAIN
STANDARD PROCEDURE
MAIN BEARING FITTING
SELECT FIT IDENTIFICATION
The main bearings are “select fit” to achieve proper oil
clearances. For main bearing selection, the crankshaft
position sensor target wheel (2) has grade identifica-
tion marks stamped into it. These marks are read from
left to right, corresponding with journal number 1, 2, 3,
4. The crankshaft position sensor target wheel is
mounted to the number 6 counter weight (1) on the
crankshaft.
INSPECTION
Wipe the inserts clean and inspect for abnormal wear patterns and for metalor other foreign material imbedded in
the lining. Normal main bearing insert wear patterns are illustrated.
Inspect the back of the inserts for fractures, scrapings or irregular wearpatterns.
Inspect the upper insert locking tabs for damage.
Replace all damaged or worn bearing inserts.
MAIN BEARING JOURNAL DIAMETER (CRANKSHAFT REMOVED)
Remove the crankshaft from the cylinder block (Refer to 9 - ENGINE/ENGINE BLOCK/CRANKSHAFT - REMOVAL).
Clean the oil off the main bearing journal.
Determine the maximum diameter of the journal with a micrometer. Measure at two locations 90° apart at each end
of the journal.
The maximum allowable taper is 0.008mm (0.0004 inch.) and maximum out of round is 0.005mm (0.002 inch). Com-
pare the measured diameter with the journal diameter specification (MainBearing Fitting Chart). Select inserts
required to obtain the specified bearing-to-journal clearance.
Install the crankshaft into the cylinder block (Refer to 9 - ENGINE/ENGINEBLOCK/CRANKSHAFT - INSPECTION).
Check crankshaft end play.
CRANKSHAFT MAIN BEARING SELECTION
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - ENGINE OIL LEAK
Begin with a thorough visual inspection of the engine, particularly at thearea of the suspected leak. If an oil leak
source is not readily identifiable, thefollowingstepsshouldbefollowed:
1. Do not clean or degrease the engine at this time because some solvents maycause rubber to swell, temporarily
stopping the leak.
2. Add an oil soluble dye (use as recommended by manufacturer). Start the engine and let idle for approximately 15
minutes. Check the oil dipstick to make sure the dye is thoroughly mixed as indicated with a bright yellow color
under a black light.
3. Using a black light, inspect the entire engine for fluorescent dye, particularly at the suspected area of oil leak. If
the oil leak is found and identified, repair per service manual instructions.
4. If dye is not observed, drive the vehicle at various speeds for approximately 24 km (15 miles), and repeat inspec-
tion.If the oil leak source is not positively identified at this time, proceed with the air leak detection test method.
Air Leak Detection Test Method
1. Disconnect the breather cap to air cleaner hose at the breather cap end. Cap or plug breather cap nipple.
2. Remove the PCV valve from the cylinder head cover. Cap or plug the PCV valvegrommet.
3. Attach an air hose with pressure gauge and regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to more than 20.6 kPa (3 PSI) of test pressure.
4. Gradually apply air pressure from 1 psi to 2.5 psi maximum while applyingsoapy water at the suspected source.
Adjust the regulator to the suitable test pressure that provide the best bubbles which will pinpoint the leak
source. If the oil leak is detected and identified, repair per service manual procedures.
5. If the leakage occurs at the rear oil seal area, refer to the section, Inspection for Rear Seal Area Leak.
6. If no leaks are detected, turn off the air supply and remove the air hose and all plugs and caps. Install the PCV
valve and breather cap hose.
7. Clean the oil off the suspect oil leak area using a suitable solvent. Drive the vehicle at various speeds approx-
imately 24 km (15 miles). Inspect the engine for signs of an oil leak by usinga black light.
INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the source of an oil leak in therear seal area of the engine, a more
involved inspection is necessary. The following steps should be followedto help pinpoint the source of the leak.
If the leakage occurs at the crankshaft rear oil seal area:
1. Disconnect the battery.
2. Raise the vehicle.
3. Remove torque converter or clutch housing cover and inspect rear of block for evidence of oil. Use a black light
to check for the oil leak:
a. Circular spray pattern generally indicates seal leakage or crankshaftdamage.
b. Where leakage tends to run straight down, possible causes are a porous block, oil galley pipe plugs, oil filter
runoff, and main bearing cap to cylinder block mating surfaces.
4. If no leaks are detected, pressurize the crankcase as outlined in the, Inspection (Engine oil Leaks in general)
CAUTION: Do not exceed 20.6 kPa (3 psi).
5. If the leak is not detected, very slowly turn the crankshaft and watch forleakage. If a leak is detected between
the crankshaft and seal while slowly turning the crankshaft, it is possible the crankshaft seal surface is damaged.
The seal area on the crankshaft could have minor nicks or scratches that canbe polished out with emery cloth.
CAUTION: Use extreme caution when crankshaft polishing is necessary to remove minor nicks and
scratches. The crankshaft seal flange is especially machined to complement the function of the rear oil seal.
6. For bubbles that remain steady with shaft rotation, no further inspection can be done until disassembled.
VALVE TIMING
DESCRIPTION
The timing drive system has been designed to provide quiet performance andreliability to support anon-free
wheelingengine. Specifically the intake valves are non-free wheeling and can be easily damaged with forceful
engine rotation if camshaft-to-crankshaft timing is incorrect. The timing drive system consists of a primary chain (6),
two secondary timing chain drives (1,4) and a counterbalance shaft drive.
OPERATION
The primary timing chain is a single inverted tooth chain type. The primarychaindrivesthelarge50toothidler
sprocket directly from a 25 tooth crankshaft sprocket. Primary chain motion is controlled by a pivoting leaf spring
tensioner arm and a fixed guide. The arm and the guide both use nylon plasticwear faces for low friction and long
wear. The primary chain receives oil splash lubrication from the secondary chain drive and designed oil pump leak-
age. The idler sprocket assembly connects the primary chain drive, secondary chain drives, and the counterbalance
shaft. The idler sprocket assembly consists of two integral 26 tooth sprockets a 50 tooth sprocket and a helical gear
that is press-fit to the assembly. Thespline joint for the 50 tooth sprocket is a non serviceable press fit anti rattle
type. A spiral ring is installed on the outboard side of the 50 tooth sprocket to prevent spline disengagement. The
idler sprocket assembly spins on a stationary idler shaft. The idler shaftis a light press-fit into the cylinder block. A
large washer on the idler shaft bolt and the rear flange of the idler shaft are used to control sprocket thrust move-
ment. Pressurized oil is routed through the center of the idler shaft to provide lubrication for the two bushings used
in the idler sprocket assembly.
There are two secondary drive chains, both are roller type, one to drive thecamshaft in each SOHC cylinder head.
There are no shaft speed changes in the secondary chain drive system. Each secondary chain drives a 26 tooth
cam sprocket directly from the 26 tooth sprocket on the idler sprocket assembly. A fixed chain guide and a hydraulic
oil damped tensioner are used to maintain tension in each secondary chain system. The hydraulic tensioners for the
secondary chain systems are fed pressurized oil from oil reservoir pockets in the block. Each tensioner incorporates
a controlled leak path through a device known as a vent disc located in the nose of the piston to manage chain
19. Install A/C compressor (2) (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/A/C
COMPRESSOR - INSTALLATION).
20. Install both breathers (1). Connect tube to both
crankcase breathers.
21. Connect throttle and speed control cables.
22. Install throttle body resonator assembly and air
inlet hose. Tighten clamps 4 Nꞏm (35 in. lbs.).
23. Raise vehicle.
24. Install transmission to engine mounting bolts.
Tighten the bolts to 41 Nꞏm (30 ft. lbs.).
25. Install torque converter bolts (Automatic Transmis-
sion Only).
26. Connect crankshaft position sensor (1).
27.4X4 vehiclesPosition and install the axle isolator
bracket onto the axle, transmission and engine
block. Tighten bolts to specification (Refer to 9 -
ENGINE - SPECIFICATIONS).
18. Remove the cylinder head access plug (1).
19. Remove the right side secondary chain guide
(Refer to 9 - ENGINE/VALVE TIMING/TIMING
BELT/CHAIN AND SPROCKETS - REMOVAL).
20. Remove the retaining bolt and the camshaft drive
gear.
CAUTION: Do not allow the engine to rotate.
severe damage to the valve train can occur.
CAUTION: Do not overlook the four smaller bolts
at the front of the cylinder head. Do not attempt to
remove the cylinder head without removing these
four bolts.
CAUTION: Do not hold or pry on the camshaft tar-
get wheel for any reason. A damaged target wheel
can result in a vehicle no start condition.
NOTE: The cylinder head is attached to the cylin-
der block with fourteen bolts.
21. Remove the cylinder head retaining bolts using
the sequence provided.
22. Remove the cylinder head and gasket. Discard the gasket.
CAUTION: Do not lay the cylinder head on its gasket sealing surface, do to the design of the cylinder head
gasket any distortion to the cylinder head sealing surface may prevent thegasket from properly sealing
resulting in leaks.
CLEANING
To ensure engine gasket sealing, proper surface preparation must be performed, especially with the use of alumi-
num engine components. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
INSPECTION
1. Inspect the cylinder head for out-of-flatness, using a straightedge and a feeler gauge. If tolerances exceed
0.0508 mm (0.002 in.) replace the cylinder head.
2. Inspect the valve seats for damage. Service the valve seats as necessary.
3. Inspect the valve guides for wear, cracks or looseness. If either condition exist, replace the cylinder head.
BEARINGS - CRANKSHAFT MAIN
STANDARD PROCEDURE - CRANKSHAFT MAIN BEARING - FITTING
MAIN BEARING JOURNAL DIAMETER (CRANKSHAFT REMOVED)
Crankshaft removed from the cylinder block.
Clean the oil off the main bearing journal.
Determine the maximum diameter of the journal with a micrometer. Measure at two locations 90° apart at each end
of the journal.
The maximum allowable taper is 0.008mm (0.0004 inch.) and maximum out of round is 0.005mm (0.002 inch). Com-
pare the measured diameter with the journal diameter specification (MainBearing Fitting Chart). Select inserts
required to obtain the specified bearing-to-journal clearance.
CRANKSHAFT MAIN BEARING SELECTION
The main bearings are “select fit” to achieve proper oil
clearances. For main bearing selection, the crankshaft
position sensor target wheel has grade identification
marks stamped into it (3). These marks are read from
left to right, corresponding with journal number 1, 2, 3,
4 and 5. The crankshaft position sensor target wheel
(2) is mounted to the number 8 counter weight (1) on
the crankshaft.
NOTE: Service main bearings are coded. These codes identify what size (grade) the bearing is.
MAIN BEARING SELECTION CHART - 4.7L
GRADE SIZE mm (in.) FOR USE WITH
MARKING JOURNAL SIZE
A0.008 mm U/S 63.488–63.496 mm
(0.0004 in.) U/S (2.4996–2.4999 in.)
BNOMINAL 63.496–63.504 mm
(2.4999–2.5002 in.)
C0.008 mm O/S 63.504–63.512 mm
(0.0004 in.) O/S (2.5002–2.5005 in.)