Engine Inspection and Repair

CYLINDER HEAD INSPECTION

Remove all carbon in the combustion chamber and exhaust port. Be sure that the water passages are open. Inspect the tapped openings. Repair or replace any damaged threads or broken studs.
Check for cylinder head distortion by placing a straightedge on the cylinder head surface. Measure the clearance between the straightedge and the cylinder head surface with a feeler gauge. If the distortion exceeds .006 inch (.15 mm), grind with a surface grinder.

MANIFOLD INSPECTION

Check the intake and exhaust manifold for distortion. To check, place the manifold on a surface plate and check the clearance between the manifold and surface plate with a feeler gauge. If excessive distortion is found, correct it by grinding. Do not grind more than .006 inch (0.15 mm) from manifold mating surface.

VALVE SPRING INSPECTION

Examine the springs for corrosion or any damage, and replace as necessary. Measure the free length and the fitting pressure. Replace with new springs if the free length is decreased under 1.425 inch (36.2 mm) on the outer spring and 1.406 (35.7 mm) in on the inner spring, or if the fitting load is reduced under 26.7 lbs. (12.1 kg) on the outer spring and 17.9 lbs. (8.1 kg) on the inner spring. Refer to specifications.

VALVE INSPECTION

Remove all carbon from the valves. Visually inspect all valves for warp, cracks or excessive burning and replace if any of these conditions are found.
Replace any worn, pitted or corroded valves that cannot be cleaned or refaced.
Measure the diameter of the valve stem at two or three places along the length of the stem with a micrometer. Replace if the stem diameter is less than 0.3142 in. (7.980 mm) on the inlet valve and 0.3140 in. (7.975 mm) on the exhaust valve.

CHECKING VALVE STEM TO GUIDE CLEARANCE

The standard clearance between the valve stem and guide is, under the condition of the guide being fitted with the cylinder head, 0.0007-0.0021 in. (0.018-0.053 mm) on the inlet side and 0.0007-0.0023 in. (0.018-0.058 mm) on the exhaust side.
To check this clearance, place the valve in each guide. Check the clearance with a suitably mounted dial indicator, or feel the clearance by moving the stem back and forth. If the clearance is 0.008 in. (0.20 mm) or more, replace the valve guide and valve.

Fig. 3 Intake & exhaust valve guide identification:

REPLACING VALVE GUIDE

1. Press out the old guide with the puller and installer (49 0221 251A).
2. Press in new guide squarely with same tool until ring on guide touches cylinder head. Intake and exhaust valve guides are different as shown in Fig. 3.

Fig. 4 Installing valve guide seal:

3. Install the new valve seal onto the valve guide with the pusher (49 0223 160B), Fig. 4.

REFACING VALVE

Reface the valves with a valve refacer, following the instructions of the valve refacer manufacturer. Take off only the minimum of metal required to clean the valve faces.
If the outer edge of the valve (valve margin) becomes less than 0.039 in. (1.0 mm) from excessive grinding, the valve must be replaced.

INSPECTING & REFACING VALVE SEAT

Inspect the valve seats for cracks, burrs, ridges or improper angle and width. If necessary to reface the valve seats, use a valve seat grinder or valve seat cutter and grind to a 45 degree angle. Do not grind any more than is necessary to clean up the valve seat.
If the valve guides are to be replaced, this must be done before refacing the valve seat. The valve seat is shrink fitted in the cylinder head and cannot be replaced.

CHECKING VALVE FACE & VALVE SEAT CONTACT

After the valve or valve seat is ground, check the contact between the valve and valve seat as follows:
1. Apply a thin coat of Prussian Blue on the valve face and insert the valve into the valve seat.
2. Move the valve up and down with hand pressure, rotating the valve.
3. Remove the valve and observe the transfer of Prussian Blue to the valve seat. An even transfer indicates accurate valve and valve seat refacing. If uneven, the valve must be lapped into the valve seat, using a suitable lapping compound.
4. Check the valve seat width with a scale. The valve seat width is 0.055 in. (1.4 mm) on both, intake and exhaust, valve seats. If the valve seat width is too wide, it can be reduced from inside with a 30° seat cutter, and from outside with a 150° seat cutter.

Fig. 5 Checking valve sinking:

CHECKING VALVE SEAT SINKING

When the valve and the valve seat have been refaced several times or they must be cut deeply for adequate reconditioning, the valve sinks below the standard position. Accordingly, the spring pressure under the fitting condition falls. Check the sinking of the valve seat by using a vernier calipers as shown in Fig. 5. Sinking of the intake valve seat should measure 1.61 inch (40.9 mm). Sinking of the exhaust valve seat should measure 1.49 inch (37.9 mm). If the sinking exceeds 0.020 in. (0.5 mm), washers of sufficient thickness to compensate the sinking must be placed under the springs so as to maintain the specified spring pressure. If it is more than 0.059 in. (1.5 mm), replace the valve.

INSPECTION OF ROCKER ARM & SHAFT

The standard clearance between the rocker arm bore and shaft is 0.0011-0.0032 in. (0.027-0.081 mm). Measure clearance and if it is more than 0.004 in. (0.10 mm), replace the rocker arm or shaft.

CYLINDER BLOCK INSPECTION

Clean the cylinder block with a suitable solvent. Special care must be taken when cleaning the oil passages, coolant passages and cylinder bore to remove all sludge, dirt and carbon deposit. After cleaning, use compressed air to dry the block thoroughly.
Examine the cylinder block for cracks and any damage. Examine all machined surfaces of the block for burrs and scores. Check the cylinder block for distort ion in the same way, as described under ``Cylinder Head Inspection.''

Fig. 6 Cylinder bore checking locations:

INSPECTING CYLINDER BORE

Check the cylinder bores for wear, scratching and distortion. Measure the diameter of the cylinder bore by using a cylinder gauge.
This measurement should be taken in the X-X direction and the Y-Y direction at each of the 3 sections, upper, middle and lower, of one cylinder, as shown in Fig. 6. The difference between the minimum and maximum values of the 6 measured values is the amount of wear. If the wear of cylinder bore is 0.0059 in. (0.15 mm) or more, it should be honed or rebored. Honing and reboring should be made to correspond to piston and rings oversize and to the recommended piston clearance of .0014-.0030 inch (.036-.075 mm).
If any one of the cylinder bores requires reboring, the remaining ones also require reboring. Reboring must not go beyond 0.040 in. (1.00 mm)
The following oversize pistons and rings are available, 0.010 inch (0.025 mm) or 0.020 inch (0.050 mm).

Fig. 7 Piston dimensions:

PISTON INSPECTION

Carefully inspect the piston and replace if it is severely scored, scratched or burned. Measure the diameter of the piston without the piston pin fitted by means of a micrometer. The standard diameter piston is shown in Fig. 7. If the wear is severe, replace the piston.

PISTON CLEARANCE

Check the clearance between each piston and cylinder by measuring the diameter of the piston and cylinder. Measure the piston diameter at right angle to the piston pin and 0.67 in. (17 mm) below the ring groove. The standard clearance is .0019-.0025 inch (.048-.063 mm). If the clearance exceeds 0.006 in. (0.15 mm), rebore the cylinders and use the oversize pistons and rings, refering to ``Inspecting Cylinder Bore.''

PISTON RING GROOVE INSPECTION

Remove the carbon from the piston ring grooves by using a ring groove cleaner or a broken piece of piston ring. With a feeler gauge, check the side clearance of the piston rings at several places. If it is improper, replace the piston rings. The standard clearances are as follows: top ring, .0012-.0028 in. (.030-.070 mm); second ring, .0012-.0025 in. (.030-.064 mm).

CHECKING PISTON RING END GAP

Place the piston ring in the cylinder bore below the ring travel, using a piston head to push the ring in squarely. Check the piston ring end gap with a feeler gauge. The end gap should be 0.008-0.016 in. (0.2-0.4 mm) for the top and second ring, and 0.012-0.035 in. (0.3-0.9 mm) for oil ring.

CHECKING PISTON PIN FIT

Check fit of piston pin and connecting rod small end bushing to be 0.0004-0.0012 in. (0.01-0.03 mm). Replace if they are worn heavily.

REPLACING SMALL END BUSHING

1. Press out the old bushing with a suitable mandrel.
2. Press fit the new bushing, being sure to align the holes of the bushing and connecting rod.
3. Finish the bushing with a reamer or a pin hole grinder to the correct fit. The fit is correct when the piston pin slides through the bushing with some pressure but without any noticeable looseness.

CONNECTING ROD BEARING

The connecting rod bearings are aluminum-lined and of the interchangeable type.
When properly installed, the bearings provide proper clearance without filing, scraping or shimming.
Each bearing consists of two halves and should be replaced as a set. The connecting rod bearing sets are available in the standard size and undersize of 0.010, 0.020 and 0.030 in. (0.25, 0.50 and 0.75 mm).
Inspect the bearing carefully and replace if it is worn, scored or flaked.

CHECKING CONNECTING ROD BEARING CLEARANCE

The connecting rod bearing clearance should be 0.0011-0.0030 in. (0.027-0.077 mm). Check the bearing clearance by using a Plastigage as follows:
1. Clean the surfaces of the bearing and crankpin.
2. Place the Plastigage on the crankpin.
3. Install the bearing cap and tighten the bolts to 30-34 ft.lbs. (40-43 N-m) to flatten the Plastigage to a width which indicates the bearing clearance.
4. Remove the cap and measure the width of the Plastigage, using the scale printed on the envelope.

CHECKING CONNECTING ROD SIDE PLAY

Check the connecting rod side play with a feeler gauge. The side play should be between 0.004-0.008 in. (0.11-0.21 mm).

CHECKING CONNECTING ROD ALIGNMENT

Check the connecting rod for bend or twist using a suitable alignment fixture. Follow the instructions of the fixture manufacturer. If the bend or twist exceeds .0008 per 1.9685 inches (.02 mm per 50 mm), the connecting rod must be straightened or replaced.

CHECKING MAIN JOURNAL & CRANKPIN

Clean the crankshaft thoroughly with a suitable solvent and blow out the oil passages with compressed air. Inspect the crankshaft for cracks or scratches and the oil passages for clogs. Measure the diameter of each crankpin and main journal with a micrometer. If the wear is more than 0.0020 in. (0.05 mm), the crankshaft should be ground to the undersize of 0.010, 0.020 and 0.030 in. (0.25, 0.50 and 0.75 mm). Refer to specifications for standard diameters of crankpins and main journals.

Fig. 8 Checking crankshaft runout:

CHECKING CRANKSHAFT ALIGNMENT

To check alignment, mount crankshaft on V-blocks and install a dial indicator, Fig. 8. Slowly rotate crankshaft and note reading on dial indicator. The maximum allowable runout is 0.0012 in. (0.03 mm). If necessary, correct with a press.

MAIN BEARING

The main bearings are of the aluminum-lined and interchangeable type. They are classified into 3 types according to the shape. When correctly installed, it provides proper clearance without filing, scraping or shimming. Each bearing consists of two halves and should be replaced as a set with the same type bearing as removed. The main bearings are available in the standard size and undersizes of 0.010, 0.020 and 0.030 in. (0.25, 0.50 and 0.75 mm). Inspect the bearings carefully for wear, scoring, flaking or any damage. If any of these conditions exist, replace with new bearings.

CHECKING MAIN BEARING CLEARANCE

Check the main bearing clearance by using a Plastigage in the same manner as for the connecting rod bearing clearance.
Note the following differences:
1. The main bearing clearance is 0.0012-0.0020 inch (0.031-0.050 mm).
2. The tightening torque for bearing cap bolts is 61-65 ft.lbs. (82-88 N-m).

CHECKING CRANKSHAFT ENDPLAY

The end thrust of the crankshaft is taken by the thrust washers at the rear of the crankshaft.
The standard endplay of the crankshaft is 0.003-0.009 in. (0.08-0.24 mm).
Check the endplay with a dial indicator or a feeler gauge. Correct if the endplay exceeds 0.012 in. (0.3 mm). The endplay can be adjusted by the thrust washer. Thrust washers are available in the oversizes of 0.010, 0.020 and 0.030 in. (0.25, 0.50 and 0.75 mm).

CAMSHAFT INSPECTION

Check to see that the cam faces and journals are smooth and are not scored or worn.
Measure the cam height with a micrometer and replace the camshaft if it is not within the specification. Measure the diameter of the camshaft journals. When they are worn more than 0.0020 in. (0.05 mm), grind the journals to the undersize of 0.010, 0.020 or 0.030 in. (0.25, 0.50 or 0.75 mm).

Fig. 9 Checking camshaft runout:

CHECKING CAMSHAFT RUNOUT

Check the camshaft runout with a dial indicator, Fig. 9. The maximum permissible runout is 0.0012 inch (0.03 mm). If necessary, correct the camshaft with a press.

Fig. 10 Camshaft bearing identification:

CAMSHAFT BEARING

The camshaft bearings are the interchangeable type. They are classified into 3 types, Fig. 10. When correctly installed, it provides proper clearance without filing, scraping or shimming.
Each bearing consists of two halves and should be replaced as a set with the same type bearing as removed. The camshaft bearings are available in the standard size and undersizes of 0.010, 0.020 and 0.030 in. (0.25, 0.50 and 0.75 mm). Inspect the bearings carefully for wear, scoring, flaking or any damage. If any of these conditions exist, replace with new bearings.

CHECKING CAMSHAFT BEARING CLEARANCE

Check the camshaft bearing clearance by using a Plastigage in the same manner as the connecting rod bearing clearance. Refer to specifications.

Fig. 11 Checking camshaft endplay:

CHECKING CAMSHAFT ENDPLAY

The endplay of the camshaft is determined by the clearance between the sprocket surface and the thrust plate surface. Measure this clearance with a feeler gauge, Fig. 11. This clearance should be 0.001-0.007 inch (0.02-0.18 mm). If the endplay is excessive, replace with a new thrust plate.

Fig. 12 Checking timing chain stretch:

CHECKING TIMING CHAIN FOR STRETCH

Before disassembly, check timing chain stretch. To check stretch, readjust chain tension and check protrusion amount of slipper head, Fig. 12. If it exceeds .67 inch (17 mm), replace the timing chain.

CHECKING TIMING CHAIN, OIL PUMP DRIVE CHAIN & SPROCKETS

Check each chain for broken links. Check the sprockets for cracks and worn or damaged teeth. If any defects are found, replace with new parts.

CHECKING CHAIN ADJUSTER

Check the slipper head on the chain adjuster for wear or damage and the adjuster spring for loss of tension. If they are defective, replace with a new adjuster assembly.

CHECKING CHAIN GUIDE STRIP & VIBRATION DAMPER

Check the chain strip and chain vibration damper for wear or any damage and replace if they are defective.