Part 1

3UZ-FE ENGINE MECHANICAL: CYLINDER HEAD: INSPECTION

1. INSPECT CYLINDER HEAD SUB-ASSEMBLY

(a) Clean the cylinder head.

(1) Using a gasket scraper, remove all the gasket material from the cylinder block contact surface.

NOTICE:
Be careful not to scratch the cylinder block contact surface.

(2) Using a wire brush, remove all the carbon from the combustion chambers.

NOTICE:
Be careful not to scratch the cylinder block contact surface.

(3) Using a valve guide bushing brush and solvent, clean all the guide bushes.

(4) Using a soft brush and solvent, thoroughly clean the cylinder head.

(b) Inspect for flatness.

(1) Using a precision straightedge and feeler gauge, measure the surfaces contacting the cylinder block and the manifolds for warpage.

Maximum warpage:

(1) If the warpage is greater than the maximum, replace the cylinder head.

(c) Inspect the cylinder head for cracks.

(1) Using a dye penetrant, check the combustion chamber, intake ports, exhaust ports and cylinder block surface for cracks.

* If the cylinder head is cracked, replace it.

2. INSPECT INTAKE VALVE

(a) Clean the valves.

(1) Using a gasket scraper, chip off any carbon from the valve head.

(2) Using a wire brush, thoroughly clean the valve.

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

Standard valve stem diameter:

5.470 to 5.485 mm (0.2154 to 0.2159 in.)

* If the diameter is greater than the maximum, replace the valve and guide bushing.

(c) Check the valve face angle.

(1) Grind the valve sufficiently to remove pits and carbon.

(2) Check that the valve is ground to the correct valve face angle.

Standard valve face angle:

44.5°

* If the valve face is worn, replace the valve.

(d) Check the valve head margin thickness.

Standard margin thickness:

1.0 mm (0.039 in.)

Minimum margin thickness:

0.5 mm (0.020 in.)

* If the margin thickness is less than the minimum, replace the valve.

(e) Check the valve overall length.

Standard overall length:

94.80 to 95.30 mm (3.7323 to 3.7520 in.)

Minimum overall length:

94.55 mm (3.7224 in.)

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

(f) Check the surface of the valve stem tip for wear.

* If the valve stem tip is worn, resurface the tip with a grinder or replace the valve.

NOTICE:
Be careful not to grind off more than the minimum.

3. INSPECT EXHAUST VALVE

(a) Clean the valves.

(1) Using a gasket scraper, chip off any carbon from the valve head.

(2) Using a wire brush, thoroughly clean the valve.

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

Standard valve stem diameter:

5.465 to 5.480 mm (0.2152 to 0.2157 in.)

* If the clearance is greater than the maximum, replace the valve and guide bushing.

(e) Check the overall valve length.

Standard overall length:

94.85 to 95.35 mm (3.7342 to 3.7539 in.)

Minimum overall length:

94.60 mm (3.7244 in.)

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

(a) Using steel squares, measure the deviation of the spring.

Maximum deviation:

2.0 mm (0.079 in.)

* If the deviation is greater than the maximum, replace the spring.

(b) Using a vernier caliper, measure the free length of the spring.

Standard free length:

54.05 to 54.15 mm (2.1279 to 2.1319 in.)

* If the free length is not as specified, replace the spring.

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

Standard installed tension:

204 to 226 N (20.8 to 23.0 kgf, 45.9 to 50.7 lbf) at 35.04 mm (1.3795 in.)

* If the installed tension is not as specified, replace the valve spring.

5. INSPECT INTAKE VALVE GUIDE BUSH

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

Standard bush inside diameter:

5.510 to 5.530 mm (0.2169 to 0.2177 in.)

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

(b) Subtract the valve stem diameter measurement from the guide bush inside diameter measurement.

Standard oil clearance:

0.025 to 0.060 mm (0.0010 to 0.0024 in.)

Maximum oil clearance:

0.08 mm (0.0031 in.)

* If the clearance is greater than the maximum, replace the valve and guide bush.

6. INSPECT EXHAUST VALVE GUIDE BUSH

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

Standard bush inside diameter:

5.510 to 5.530 mm (0.2169 to 0.2177 in.)

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

(b) Subtract the valve stem diameter measurement from the guide bush inside diameter measurement.

Standard oil clearance:

0.030 to 0.065 mm (0.0012 to 0.0026 in.)

Maximum oil clearance:

0.10 mm (0.0039 in.)

* If the clearance is greater than the maximum, replace the valve and guide bush.

7. INSPECT INTAKE VALVE SEAT

(a) Using a 45° carbon cutter, resurface the valve seats.

HINT
Only remove the amount of metal necessary to clean the seats.

(b) Check the valve seating position.

(1) Apply a light coat of Prussian blue (or white lead) to the valve face.

(2) Lightly press the valve against the seat. Do not rotate the valve.

(c) Check the valve face and seat for the following:

(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 and has the width indicated below.

Standard width:

1.0 to 1.4 mm (0.039 to 0.055 in.)

* If the width is not as specified, correct the exhaust valve seats as follows:

(d) If the seating is too high on the valve face:

* Use 30° and 45° cutters to correct the seat.

(e) If the seating is too low on the valve face:

* Use 60° and 45° cutters to correct the seat.

(f) Hand rub the valve and valve seat with an abrasive compound.

(g) After hand-rubbing, clean the valve and valve seat.

8. INSPECT EXHAUST VALVE SEAT

(a) Using a 45° carbon cutter, resurface the valve seats.

HINT
Only remove the amount of metal necessary to clean the seats.

* If the width is not as specified, correct the exhaust valve seats as follows:

(d) If the seating is too high on the valve face:

* Use 30° and 45° cutters to correct the seat.

(e) If the seating is too low on the valve face:

* Use 60° and 45° cutters to correct the seat.

(f) Hand rub the valve and valve seat with an abrasive compound.

(g) After hand-rubbing, clean the valve and valve seat.

9. INSPECT VALVE LIFTER

(a) Using a micrometer, measure the lifter diameter at a position 10.5 to 14.5 mm (0.413 to 0.570 in.) from the top surface.

Standard lifter diameter:

30.968 to 30.976 mm (1.2192 to 1.2195 in.)

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

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

Standard lifter bore diameter:

31.000 to 31.016 mm (1.2205 to 1.2211 in.)

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

(c) Subtract the lifter diameter measurement from the lifter bore diameter measurement.

Standard oil clearance:

0.024 to 0.048 mm (0.0009 to 0.0018 in.)

Maximum oil clearance:

0.07 mm (0.0028 in.)

* If the oil clearance is greater than the maximum, replace the lifter. If necessary, replace the cylinder head.