Camshaft and Cylinder Head Inspection

1. Clean top of pistons and top of block:
a. Turn the crankshaft and bring each piston to top dead center (TDC). Using a gasket scraper, remove all the carbon from the piston top.

IMPORTANT: Cover front of the engine with a shop towel to prevent debris from entering the oil gallery holes and pan.

CAUTION: PROTECT YOUR EYES WHEN USING HIGH PRESSURE AIR.






b. Remove all the gasket material from the top of the block using a plastic or wood scraper.
c. Blow carbon and oil from the bolt holes.

NOTICE: Be careful not to scratch or score the cylinder block and head aluminum surfaces when cleaning.






2. Remove gasket material from cylinder head:
a. Using a plastic or wood gasket scraper, remove all the gasket material from the manifold and head surface.

NOTICE: Intake and exhaust manifold stud threads can be damaged during removal and must be replaced when a new machined cylinder head casting is installed.

NOTICE: Be careful not to scratch the head gasket contact surface when cleaning cylinder head.






3. Using a wire brush, remove all the carbon from the combustion chambers.





4. Using a valve guide bushing brush and solvent, clean all the valve guide bushings.
5. Using a soft brush and solvent, thoroughly clean the cylinder head:
a. Intake and exhaust ports.
b. Intake and exhaust valve seats and guides.






6. Inspect cylinder head for flatness. Using a precision straight edge SA9177NE (or equivalent) and feeler gauge SA911O1NE (or equivalent), measure the surfaces contacting the cylinder block and manifolds for warpage. If warpage is greater than maximum, replace the cylinder head.

MAXIMUM WARPAGE SPECIFICATIONS:
Cylinder Block Side:
Transverse:
^ Standard: 0.03 mm (0.0012 in.)
^ Service Limit: 0.05 mm (0.002 in.) max.

Longitudinal:
^ Standard: 0.07 mm (0.0028 in.)
^ Service Limit: 0.10 mm (0.004 in.) max.

Intake Manifold Side:
Longitudinal:
^ Standard: 0.10 mm (0.004 in.)
^ Service Limit: 0.15 mm (0.006 in.) max.

Exhaust Manifold Side:
Longitudinal:
^ Standard: 0.10 mm (0.004 in.)
^ Service Limit: 0.15 mm (0.006 in.) max.

EGR Flange:
^ Standard: 0.10 mm (0.004 in.) max.
^ Service Limit: 0.15 mm (0.006 in.) max.





7. Inspect cylinder head for cracks. Using a dye penetrate, check the combustion chamber intake and exhaust ports, head surface, and the top of the head (around all bolt holes) for cracks. If cracked, replace the cylinder head.





8. Clean the valves:
a. Using a gasket scraper, or wire brush, remove any carbon from the valve head.





9. Inspect valve stems and guides for wear, scratches, and burrs.

IMPORTANT: A small scratch, score or scuff on the valve stem will damage and wear out the valve stem seal.






a. Using a ball gauge, or SA91102NE (or equivalent) measure the inside diameter of the valve guide bushing at three locations.

Guide Bushing Inside Diameter:
^ Standard: 6.987-7.013 mm (0.2751-0.276 in.)
^ Service Limit: 7.050 mm (0.277 in.) max.





b. Using a micrometer, measure the diameter of the valve stem.

Valve Stem Diameter:
Intake:
^ Standard: 6.949-6.962 mm (0.2736-0.2741 in.)
^ Service Limit: 6.931-6.950 mm (0.2729-0.2736 in.)

Exhaust:
^ Standard: 6.937 mm (0.273 in.) min.
^ Service Limit: 6.919 mm (0.272 in.) min.

c. Subtract the valve stem diameter measurement from the valve guide bushing inside diameter measurement. If the clearance is greater than maximum, replace the valve and guide bushing.

Oil Clearance:
Intake:
^ Standard: 0.025-0.064 mm (0.001-0.0025 in)
^ Service Limit: 0.115 mm (0.0044 in.) max.

Exhaust:
^ Standard: 0.037-0.082 mm (0.0015-0.0032 in.)
^ Service Limit: 0.131 mm (0.005 in.) max.

NOTICE: Lifter bores are machined surfaces and must not be damaged when installing valve guides, valves, seals, caps, retainers, and lifters.





10. If necessary, replace valve guide bushings:
a. Using the driver SA9126E-1 and a hammer, drive out the valve guide bushing.






b. Using a ball hole gauge or SA91102NE (or equivalent), measure the bushing bore diameter in the cylinder head. If the bushing bore diameter of the cylinder head is more than 11.368 mm (0.4475 in.), use the large reamer SA9126E-5 and ream the bore to the following dimensions to install an oversized bushing (11.587-11.613 mm [0.456-0.457 in.]). If the bushing bore diameter of the cylinder head exceeds 11.613 mm (0.457 in.), replace the cylinder head.

Cylinder Head Valve Guide Bore (Cold):
^ Standard: 11.337-11.363 mm (0.446-0.447 in.)
^ Service Limit: 11.368 mm (0.4475 in.) max.

Oversize Bore: 11.587-11.613 mm (0.456-0.457 in.)








c. Using drivers SA9126E1 and E2 and a hammer, drive in a new valve guide bushing.

Guide Height above Cylinder Head Valve:
Spring Seat: 10.25-10.50 mm (0.4035-0.4133 in.)

IMPORTANT: Do not oil or use any thread locking materials when installing valve guides.






d. Using the two sharp reamers SA9126E2-E4, ream the valve guide bushing to obtain the specified clearance between the valve guide bushing and the new valve stem.

IMPORTANT: Two special reamers are required to ream the guide. Oil the reamer with SAE 5W30 SG engine or cutting oil. Slowly drive the small reamer through the valve guide bore with a 1/2 HP drill motor set at 500 rpm. Check the valve guide bore to valve stem clearance first. If required, slowly drive the second (larger) reamer through the guide to obtain the specified clearance.

IMPORTANT: Make sure the reamer flutes are clean prior to reaming each guide.

Clearance:
Intake:
^ Standard: 0.025-0.064 mm (0.001-0.0025 in.)
^ Service Limit: 0.113 mm (0.0044 in.) max.

Exhaust:
^ Standard: 0.037-0.082 mm (0.0015-0.0032 in.)
^ Service Limit: 0.131 mm (0.005 in.) max.






11. Inspect and grind valves:
a. Grind the valve only enough to remove pits and carbon.

IMPORTANT: If the valve head is cupped, it must be replaced.






b. Check that the valve is ground to the correct valve face angle.

Valve Face Angle: Intake and Exhaust
^ Standard: 44.5-45.0 degrees






c. Check the valve head margin thickness. If the valve head margin thickness is less than minimum, replace the valve.

Margin Thickness:
Intake:
^ Service Limit: 0.75 mm (0.0295 in.) min.

Exhaust:
^ Service Limit: 0.75 mm (0.0295 in.) min.





d. Check the valve overall length. If the valve overall length is less than minimum, replace the valve.

Minimum Overall Length:
Intake:
^ Standard: 100.72-101.18 mm (3.9654-3.9835 in.)
^ Service Limit: 100.64-101.26 mm (3.962-3.987 in.)

Exhaust:
^ Standard: 100.02-100.48 mm (3.9378-3.9560 in.)
^ Service Limit: 99.94-100.56 mm (3.935-3.959 in.)

NOTICE: Do not grind off more than the minimum overall length.






e. Check the surface of the valve stem tip for damage. If the valve stem tip is damaged, grind the valve stem tip with a grinder until flat. Replace the valve if necessary.





12. Inspect and clean valve seats.

IMPORTANT: Valve seats are released for service and can be replaced. Damaged seats are usually replaced by a machine shop.

Cylinder Head Dimensions:
Intake Valve Seat Bore:
^ Standard: 33.399-33.423 mm (1.315-1.316 in.)

Exhaust Valve Seat Bore:
^ Standard: 28.399-28.423 mm (1.118-1.119 in.)

Valve Seat Outside Diameter:
Intake:
^ Standard: 33.49-33.51 mm (.318-.319 in.)

Exhaust:
^ Standard: 28.49-28.51 mm (1.121-1.122 in.)






a. Using a 44.5-45 degree carbide cutter or stone, resurface the valve seats. Remove only enough metal to clean the seats. Check the valve seat width:

Valve Seat Width:
Intake:
^ Standard: 0.79-1.23 mm (0.031-0.048 in.)
^ Service Limit: 1.66 mm (0.0653 in.) max.

Exhaust:
^ Standard: 1.05-1.49 mm (0.041-0.058 in.)
^ Service Limit: 1.92 mm (0.0756 in.) max.






b. Check the valve seating position. Apply a thin coat of Prussian blue (or white lead) to the valve face. Install the valve. While applying light pressure to the valve, rotate the valve against the seat.





c. Check the valve face and seat for the following:
^ If blue appears 360 degrees around the face, the valve is concentric. If not, replace the valve.
^ If blue appears 360 degrees around the valve seat, the guide and seat are concentric. If not, resurface the seat.
^ Check that the seat contact is on the middle of the valve face. If not, correct the valve seat as follows:





- If the seating is too high on the valve face, use 30 degrees and 45 degree cutters or stones to correct the seat width.





- If the seating is too low on the valve face, use 60 degrees and 45 degree cutters or stones to correct the seat.






d. Hand-lap the valve and valve seat with an abrasive compound.
e. Clean the valve and valve seat after lapping using solvent.





f. Install the valve without seal and measure the tip height with calipers.

Maximum Height Dimension:
^ Standard: 40.95-41.55 mm (1.612-1.636 in.)
^ Service Limit: 40.95 mm (1.612 in.) min. 41.60 mm (1.638 in.) max.





13. Inspect valve springs:
a. Using a ruler, measure the height of the valve spring at four locations. If the valve spring is bent, replace it.

Maximum Squareness:
^ Standard: 2.0 mm (0.080 in) max.
^ Service Limit: 2.5 mm (0.100 in.) max.





b. Using calipers or service tool SA9179NE (or equivalent), measure the free length of the valve spring. If the free length is not within specification, replace the valve spring.

Free Length:
^ Standard: 41.8 mm (1.65 in.) min.





c. Using a spring tester SA9183NE (or equivalent), fully collapse the spring three times, then measure the tension of the valve spring at the specified installed length. If the installed tension is not as specified, replace the valve spring.

Tension at 26.25 mm (1.033 in.):
^ Standard: 724-788 N (163-177 lbs.)
^ Service Limit: 688 N (155 lbs.) min.

Tension at 35.25 mm (1.388 in.):
^ Standard: 293-329 N (66-74 lbs.)
^ Service Limit: 278 N (63 lbs.) min.





14. Check the hydraulic lifter diameter and cylinder head bore for wear.

Lifter Diameter:
^ Standard: 32.959-32.975 mm (1.2976-1.2982 in.)
^ Service Limit: 32.947 mm (1.297 in.) min.

Cylinder Head Bore Diameter:
^ Standard: 33.000-33.025 mm (1.2992-1.3002 in.)
^ Service Limit: 33.030 mm (1.3004 in.) max.

Oil Clearance:
^ Standard: 0.025-0.066 mm (0.0010-0.0026 in.)
^ Service Limit: 0.083 mm (0.003 in.) max.

NOTICE: Lifters must be installed in the same bores. Lifters are very difficult to repair and must be replaced as an assembly.






15. Inspect and clean lifters (externally):

IMPORTANT:A welded joint exists 2 mm (0.080 in.) from the bottom of the lifter (contact surface with camshaft lobe). The 0.2 mm (0.008 in.) maximum wide weld mark must not be mistaken for a crack.





16. Inspect intake and exhaust manifolds. Using a precision straight edge and feeler gauge, measure the surfaces contacting the cylinder head, intake manifold and exhaust manifold for warpage. If warpage is greater than maximum, replace the manifold.

Warpage:
Intake Manifold-to-Cylinder Head:
^ Standard: 0.13 mm (0.0051 in.) max.
^ Service Limit: 0.20 mm (0.008 in.) max.

Exhaust Manifold-to-Cylinder Head:
^ Standard: 0.25 mm (0.010 in.) max.
^ Service Limit: 0.35 mm (0.014 in.) max.

Intake Manifold-to-Throttle Body:
^ Standard: 0.10 mm (0.004 in.) max
^ Service Limit: 0.15 mm (0.006 in.)

Exhaust Manifold-to-Front Exhaust Pipe Flange:
^ Standard: 0.4 mm (0.016 in.) max.
^ Service Limit: 0.4 mm (0.016 in.) max.

Intake Manifold EGR Flange:
^ Standard: 0.10 mm (0.004 in.) max.
^ Service Limit: 0.15 mm (0.006 in.) max.