Cylinder Head (For Sedan) Inspection

Using a precision straightedge and feeler gauge, measure the warpage of the surface that is in contact with the cylinder block and the manifolds.

Maximum warpage:

Surface	Specified Condition
Cylinder block side	0.05 mm (0.0020 in.)
Intake manifold side	0.10 mm (0.0039 in.)
Exhaust manifold side	0.10 mm (0.0039 in.)

Using a dye penetrate, check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks.
If cracked, replace the cylinder head.

Using vernier calipers, measure the length of the head bolts from the seat to the end.

Standard length:

142.8 to 144.2 mm (5.622 to 5.677 in.)

Maximum length:

147.1 mm (5.791 in.)

Check the overall valve length.

Standard overall length:

89.25 mm (3.5138 in.)

Minimum overall length:

88.75 mm (3.4941 in.)

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

Standard valve stem diameter:

4.970 to 4.985 mm (0.1957 to 0.1963 in.)

Check the valve head margin thickness.

Standard margin thickness:

1.0 mm (0.039 in.)

Minimum margin thickness:

0.5 mm (0.020 in.)

Check the overall valve length.

Standard overall length:

87.90 mm (3.4606 in.)

Minimum overall length:

87.40 mm (3.4409 in.)

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

Standard valve stem diameter:

4.965 to 4.980 mm (0.1955 to 0.1961 in.)

Check the valve head margin thickness.

Standard margin thickness:

1.15 mm (0.045 in.)

Minimum margin thickness:

0.5 mm (0.020 in.)

Using vernier calipers, measure the free length of the valve spring.

Standard free length:

45.05 to 45.15 mm (1.774 to 1.778 in.)

Using a steel square, measure the deviation of the valve spring.

Maximum deviation:

1.6 mm (0.063 in.)

Maximum angle (reference):

2°

Using a spring tester, measure the tension of the valve spring at the specified installed length.

Standard installed tension:

149 to 165 N (15.2 to 16.8 kgf, 33.5 to 37.1 lbf) at 32.5 mm (1.280 in.)

Maximum working tension:

286 to 316 N (29.1 to 32.2 kgf, 64.2 to 71.0 lbf) at 23.9 mm (0.941 in.)

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

Bush inside diameter:

5.010 to 5.030 mm (0.1972 to 0.1980 in.)

Subtract the valve stem diameter measurement from the guide bush inside diameter measurement to calculate the oil clearance.

Standard oil clearance:

Guide Bush	Specified Condition
Intake	0.025 to 0.060 mm (0.0010 to 0.0024 in.)
Exhaust	0.030 to 0.065 mm (0.0012 to 0.0026 in.)

Maximum oil clearance:

Guide Bush	Specified Condition
Intake	0.08 mm (0.0032 in.)
Exhaust	0.10 mm (0.0039 in.)

Apply a light coat of prussian blue to the valve face.

Lightly press the valve against the seat.

Check the valve face and seat in accordance with the following procedure.

1. If blue appears 360° around the face, the valve is concentric. If not, replace the valve.
   

2. If blue appears 360° around the valve seat, the guide and face are concentric. If not, resurface the seat.
   

3. Check that the seat contact is in the middle of the valve face with the width between 1.0 to 1.4 mm (0.039 to 0.055 in.).
   

Using a micrometer, measure the lifter diameter.

Standard lifter diameter:

30.966 to 30.976 mm (1.2191 to 1.2195 in.)

Using a caliper gauge, measure the lifter bore diameter of the cylinder head.

Standard lifter bore diameter:

31.000 to 31.025 mm (1.2205 to 1.2215 in.)

Subtract the lifter diameter measurement from the lifter bore diameter measurement to calculate the oil clearance.

Standard oil clearance:

0.024 to 0.059 mm (0.0009 to 0.0023 in.)

Maximum oil clearance:

0.1 mm (0.0039 in.)

Inspect the camshaft for runout.

1. Place the camshaft on V-blocks.
   

2. Using a dial indicator, measure the circle runout at the center journal.
   

   Maximum circle runout:

   0.03 mm (0.0012 in.)
   

   If the circle runout is greater than the maximum, replace the camshaft.
   

Inspect the cam lobes.

1. Using a micrometer, measure the cam lobe height.
   

   Standard cam lobe height:

   44.617 to 44.717 mm (1.7566 to 1.7605 in.)
   

   Minimum cam lobe height:

   43.16 mm (1.6992 in.)
   

   If the cam lobe height is less than the minimum, replace the camshaft.
   

Inspect the camshaft journals.

1. Using a micrometer, measure the journal diameter.
   

   Standard journal diameter:

   Journal	Specified Condition
   No. 1 journal	34.449 to 34.465 mm (1.3563 to 1.3569 in.)
   Other journals	22.949 to 22.965 mm (0.9035 to 0.9041 in.)

   If the journal diameter is not as specified, check the oil clearance.
   

Inspect the camshaft for runout.

1. Place the camshaft on V-blocks.
   

2. Using a dial indicator, measure the circle runout at the center journal.
   

   Maximum circle runout:

   0.03 mm (0.0012 in.)
   

   If the circle runout is greater than the maximum, replace the camshaft.
   

Inspect the cam lobes.

1. Using a micrometer, measure the cam lobe height.
   

   Standard cam lobe height:

   44.666 to 44.766 (1.7585 to 1.7624 in.)
   

   Minimum cam lobe height:

   44.52 mm (1.7528 in.)
   

   If the cam lobe height is less than the minimum, replace the camshaft.
   

Inspect the camshaft journals.

1. Using a micrometer, measure the journal diameter.
   

   Standard journal diameter:

   Journal	Specified Condition
   No. 1 journal	34.449 to 34.465 mm (1.3563 to 1.3569 in.)
   Other journals	22.949 to 22.965 mm (0.9035 to 0.9041 in.)

   If the journal diameter is not as specified, check the oil clearance.
   

Install the camshafts.

Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.

Standard thrust clearance:

0.040 to 0.095 mm (0.0016 to 0.0037 in.)

Maximum thrust clearance:

0.11 mm (0.0043 in.)

Clean the bearing caps and the camshaft journals.

Place the camshafts on the cylinder head.

Lay a strip of Plastigage across each of the camshaft journals.

Install the bearing caps (YARIS_NCP93 RM000001DCP012X_01_0002.html).

NOTICE:

Do not turn the camshaft.

Remove the bearing caps.

Measure the Plastigage at its widest point.

Standard oil clearance:

0.035 to 0.072 mm (0.0014 to 0.0028 in.)

Maximum oil clearance:

0.08 mm (0.0031 in.)

NOTICE:

Completely remove the Plastigage after the measurement.