CYLINDER HEAD INSPECTION

PROCEDURE

INSPECT CYLINDER HEAD FOR FLATNESS

Using a precision straightedge and feeler gauge, measure the warpage of the contact surfaces where the cylinder head contacts the cylinder block sub-assembly and manifolds.

*a	Cylinder Head Lower Side	*b	Intake Manifold Side
*c	Exhaust Manifold Side	-	-

Maximum Warpage

Item	Specified Condition
Cylinder Head Lower side	0.05 mm (0.00197 in.)
Intake manifold side	0.10 mm (0.00394 in.)
Exhaust manifold side	0.10 mm (0.00394 in.)

If the warpage is more than the maximum, replace the cylinder head sub-assembly.

INSPECT CYLINDER HEAD FOR CRACKS
1. Using a dye penetrant, check the intake ports, exhaust ports and cylinder head sub-assembly surface for cracks.
  
  If cracks are found, replace the cylinder head sub-assembly.
INSPECT INTAKE VALVE
1. Using a vernier caliper, measure the valve overall length of the intake valve.
  
  Standard overall length
  
  109.34 mm (4.30 in.)
  
  Minimum overall length
  
  108.84 mm (4.29 in.)
  
  If the overall length is less than the minimum, replace the intake valve.
2. Using a micrometer, measure the diameter of the valve stem.
  
  Standard valve stem diameter
  
  5.470 to 5.485 mm (0.215 to 0.216 in.)
  
  If the diameter is not as specified, check the oil clearance.
3. *a Margin Thickness
  
  Using a vernier caliper, measure the valve head margin thickness.
  
  Standard margin thickness
  
  1.0 mm (0.0394 in.)
  
  Minimum margin thickness
  
  0.5 mm (0.0197 in.)
  
  If the margin thickness is less than the minimum, replace the intake valve.
INSPECT EXHAUST VALVE
1. Using a vernier caliper, measure the valve overall length of the exhaust valve.
  
  Standard overall length
  
  108.25 mm (4.26 in.)
  
  Minimum overall length
  
  107.75 mm (4.24 in.)
  
  If the overall length is less than the minimum, replace the exhaust valve.
2. Using a micrometer, measure the diameter of the valve stem.
  
  Standard valve stem diameter
  
  5.465 to 5.480 mm (0.215 to 0.216 in.)
  
  If the diameter is not as specified, check the oil clearance.
3. *a Margin Thickness
  
  Using a vernier caliper, measure the valve head margin thickness.
  
  Standard margin thickness
  
  1.0 mm (0.0394 in.)
  
  Minimum margin thickness
  
  0.5 mm (0.0197 in.)
  
  If the margin thickness is less than the minimum, replace the exhaust valve.
INSPECT COMPRESSION SPRING
1. Using a vernier caliper, measure the free length of the compression spring.
  
  Standard free length
  
  51.88 mm (2.04 in.)
  
  If the free length is not as specified, replace the compression spring.
2. *a Deviation
  
  *b 37.5 mm (1.48 in.)
  
  Using a steel square, measure the deviation of the compression spring.
  
  Maximum deviation
  
  1.3 mm (0.0512 in.)
  
  If the deviation is more than the maximum, replace the compression spring.

Standard overall length
109.34 mm (4.30 in.)

Minimum overall length
108.84 mm (4.29 in.)

Standard valve stem diameter
5.470 to 5.485 mm (0.215 to 0.216 in.)

Standard margin thickness
1.0 mm (0.0394 in.)

Minimum margin thickness
0.5 mm (0.0197 in.)

Standard overall length
108.25 mm (4.26 in.)

Minimum overall length
107.75 mm (4.24 in.)

Standard valve stem diameter
5.465 to 5.480 mm (0.215 to 0.216 in.)

Standard margin thickness
1.0 mm (0.0394 in.)

Minimum margin thickness
0.5 mm (0.0197 in.)

Standard free length
51.88 mm (2.04 in.)

Maximum deviation
1.3 mm (0.0512 in.)

INSPECT VALVE GUIDE BUSH OIL CLEARANCE

Using a caliper gauge, measure the inside diameter of the valve guide bush.

Standard valve guide bush inside diameter

5.510 to 5.530 mm (0.217 to 0.218 in.)

Standard valve guide bush inside diameter
5.510 to 5.530 mm (0.217 to 0.218 in.)

Subtract the valve stem diameter measurement from the valve guide bush inside diameter measurement.

Standard Oil Clearance

Item	Specified Condition
Intake	0.025 to 0.060 mm (0.000984 to 0.00236 in.)
Exhaust	0.030 to 0.065 mm (0.00118 to 0.00256 in.)

Maximum Oil Clearance

Item	Specified Condition
Intake	0.080 mm (0.00315 in.)
Exhaust	0.085 mm (0.00335 in.)

Tech Tips

Oil clearance = Inside diameter - Valve stem diameter
If the oil clearance is more than the maximum, replace the valve and valve guide bush.

INSPECT VALVE SEATS
1. Apply a light coat of Prussian blue to the valve face.
2. Lightly press the valve face against the valve seat.
  
  Tech Tips
  
  Do not rotate the valve while pressing the valve.
3. *a Width
  
  Check the valve face and valve seat.
  1. Intake Side:
    
    Check that the contact surfaces of the valve seat and valve face are in the middle area of their respective surfaces, with the width between 1.0 and 1.4 mm (0.0394 and 0.0551 in.).
    
    If not, correct the valve seat.
  2. Exhaust Side:
    
    Check that the contact surfaces of the valve seat and valve face are in the middle area of their respective surfaces, with the width between 1.0 and 1.4 mm (0.0394 and 0.0551 in.).
    
    If not, correct the valve seat.
  3. Check that the contact surfaces of the valve seat and valve face are even around the entire valve seat.
    
    If not, correct the valve seat.
INSPECT CAMSHAFT THRUST CLEARANCE
1. Install the camshaft housing sub-assembly.
  
  Click here
  
  Tech Tips
  
  Do not use seal packing when installing the camshaft housing sub-assembly, as the installation is temporary.
2. Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.
  
  Standard thrust clearance
  
  0.06 to 0.155 mm (0.00236 to 0.00610 in.)
  
  Maximum thrust clearance
  
  0.17 mm (0.00669 in.)
  
  If the thrust clearance is more than the maximum, replace the camshaft housing sub-assembly.

*a	Deviation
*b	37.5 mm (1.48 in.)