Engine Inspection and Repair
CYLINDER HEAD INSPECTION
Replace the cylinder head if there is any evidence of wear or damage. Measure cylinder head warp on the lower mating surface. If the warp is more than .006 inch (.15 mm), grind the mating surface. Do not grind more than .008 inch (0.2 mm) from mating surface.
VALVE GUIDE INSPECTION
Measure the clearance between the valve and guide. If the clearance exceeds .0079 inch (0.20 mm), replace the valve, guide or both. To replace the valve guide, remove valve seal from valve guide. Using tool No. 490221251A or equivalent, knock valve guide out toward the opposite side of the combustion chamber. Using tool described, install clip onto new valve guide. Using a hammer and suitable drift, install new valve guide into cylinder head.
VALVE INSPECTION
Minor damage to the valves can be corrected by grinding. Using a micrometer, measure valve stem diameter. Minimum valve stem diameter should be .0394 inch (1.0 mm). Limit of diameter reduction for the intake valve should not exceed .3142 inch (7.980 mm), and for exhaust valve .3140 inch (7.975 mm). If the thickness of the valve stem is less than specified limit, replace the valve as required.
VALVE SPRING INSPECTION
Check the valve spring for cracks and damage, replace as required. Measure free length of spring. Free length should be 1.654 inch (42.0 mm). If free length of spring is less than specified limit, replace the valve spring as required.
Using a straightedge, check right angle limit. Right angle limit should be less than 0.118 inch (3 mm) per 3.937 inch (100 mm). If right angle is more than specified limit, replace valve spring.
Fig. 4 Intake and exhaust valve seat dimensions:
VALVE SEAT INSPECTION
If the surface on the valve seat which is in contact with the valve face is damaged, repair by grinding as follows:
1. Make sure clearance between valve guide and stem is correct.
2. Cut the valve seat surface with a 90° grinder so the width of surface in contact with the valve becomes 0.055 inch (1.4 mm), Fig. 4.
3. Ensure area in contact with the valve is at center of the valve face.
4. Improve valve and valve seat fit by using a suitable lapping compound and lapping the valve.
5. Check valve seat wear. If the valve seat has worn less than .020-.059 inch (0.5-1.5 mm), position washers equal to the depth in wear onto the valve spring seat. If the wear depth is more than .059 inch (1.5 mm), replace as required.
ROCKER ARM & ROCKER ARM SHAFT INSPECTION
Replace rocker arm or cam if contact surfaces are damaged or worn. Measure rocker arm and shaft clearance. Clearance limit should be .0039 inch (0.10 mm). If clearance is not within specified limit, replace rocker arm shaft assembly.
CYLINDER BLOCK INSPECTION
Check cylinder block for cracks and wear. Replace if necessary. Measure upper surface area for warping. Warp limit should not exceed .006 inch (.15 mm). If warping is more than specified limit, grind the mating surface. Do not grind more than .008 inch (0.2 mm) from mating surface.
Check cylinder walls for scratches or burns. Rebore the walls as required. Standard bore diameter is 3.0201-3.0268 inch (77.0-77.019 mm). Maximum bore difference is .0059 inch (.15 mm). Inner diameter error of each cylinder is .0035 inch (0.09 mm) or less. After boring cylinder walls select oversize pistons according to the maximum wear on the cylinder bore. The following oversize pistons are available: .010 inch (.25 mm), .020 inch (.50 mm).
PISTON INSPECTION
Check the pistons for burns or scratches on the outside circumference of the piston. Using a micrometer, measure piston diameter under the oil ring groove, at right angles with the piston pin location. Piston diameter should be 3.0297-3.0305 inch (76.954-76.974 mm). Measure clearance between piston and cylinder wall, which should be .0059 inch (.15 mm).
PISTON RING INSPECTION
Check piston rings for wear. Replace any broken ring. Push piston rings into the cylinder bore, and measure piston ring end gap. End gap limit is .039 inch (1.0 mm). Measure piston ring and ring groove clearance. Measure the clearance around the total circumference of the ring groove.
Ring groove and ring clearance limit is .006 inch (.15 mm).
CONNECTING ROD & BEARING INSPECTION
Check connecting rod for any bending or twisting. Maximum allowable twist is .002 inch (.04 mm) per 3.937 inch (100 mm).
Fig. 5 Checking locations for crankshaft wear:
CRANKSHAFT & MAIN BEARING INSPECTION
Check crankshaft for evidence of wear and damage. Check for clogged oil passages. Using a dial indicator, check crankshaft runout. Runout should not exceed .0012 inch (.03 mm). Measure uneven wear on the journal and pin, at the four indicated locations (A and B), Fig. 5. Maximum uneven wear allowed is .002 inch (.05 mm). If wear exceeds specified limit, replace the bearing with an undersized bearing and grind the crankshaft to properly fit the undersized bearing. Check crankshaft bearings for peeling, damage or seizure and replace bearings as required.
Fig. 6 Checking location for camshaft wear:
CAMSHAFT INSPECTION
Check camshaft for evidence of wear and damage, and replace if necessary. Using a dial indicator, measure runout. Runout should not exceed .0012 inch (.03 mm). If runout exceeds specified limit, replace camshaft. Using a micrometer, measure cam lobe height. Standard cam lobe height is 1.7337 inch (44.114 mm). Measure uneven wear on the camshaft journals at the four indicated locations, Fig. 6. Maximum uneven wear allowed is .0020 inch (.05 mm). Standard journal diameter front and rear should be 1.6486-1.6492 inch (41.949-41.965 mm). Center journal diameter should be 1.6474-1.6480 inch (41.919-41.935 mm).
FLYWHEEL INSPECTION
Check the flywheel for cracks and wear, and replace if necessary. Position flywheel onto a flat surface, and measure warp. Flywheel warp should not exceed .008 inch (.20 mm). If flywheel warp exceeds specified limit replace flywheel. Replace flywheel ring gear as follows:
1. Using a suitable torch, heat ring gear.
2. Using a hammer, tap circumference of ring gear and remove from flywheel.
3. Heat the new ring gear to 480°-570° F, (250-300° C), and install onto flywheel. Ensure chamfered side of ring gear faces the engine.
Fig. 7 Timing chain stretch check:
CHAIN, CHAIN ADJUSTER, BLADE, DAMPER & SPROCKET INSPECTION
Check each component for wear and damage, replace components if necessary.
Check contacting position of stopper and sleeve. If protrusion is between 13 and 18 notches, Fig. 7, the chain has stretched excessively and must be replaced.