Cylinder Head Inspection

Clean the cylinder head.

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

   NOTICE:

   Do not scratch the surface that contacts the cylinder block.

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

NOTICE:

Do not scratch the surface that contacts the cylinder block.

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

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

Inspect the cylinder head warpage.

1. Using a precision straightedge and feeler gauge, measure the surfaces that contact the cylinder block and the manifolds for warpage.
   

   Maximum warpage:

   0.20 mm (0.00787 in.)
   

   Text in Illustration

   *a	Cylinder Block Side:
   *b	Intake Manifold Side:
   *c	Exhaust Manifold Side:

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

Inspect the cylinder head for cracks.

1. Using a dye penetrant, check the combustion chamber, intake ports, exhaust ports and cylinder head surface for cracks.
   If cracked, replace the cylinder head sub-assembly.
   

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

Using a wire brush, thoroughly clean the valve.

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

Standard valve stem diameter:

7.975 to 7.990 mm (0.3140 to 0.3146 in.)

Check the valve face angle.

1. Grind the valve enough to remove any pits and carbon.
   

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

   Standard valve face angle:

   44.5°
   

   Text in Illustration

   *1	Valve Face Angle

   If the valve is worn, replace the intake valve.
   

Check the head margin thickness.

Standard margin thickness:

1.6 mm (0.0630 in.)

Minimum margin thickness:

1.1 mm (0.0433 in.)

Check the overall length of the valve.

Standard overall length:

104.10 to 104.50 mm (4.10 to 4.11 in.)

Minimum overall length:

103.60 mm (4.08 in.)

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 intake valve.

NOTICE:

Do not grind the valve so it becomes shorter than the minimum overall length.

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

Standard valve stem diameter:

7.960 to 7.975 mm (0.3134 to 0.3140 in.)

Check the valve face angle.

1. Grind the valve enough to remove any pits and carbon.
   

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

   Standard valve face angle:

   44.5°
   

   Text in Illustration

   *1	Valve Face Angle

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

Check the valve head margin thickness.

Standard margin thickness:

1.7 mm (0.0669 in.)

Minimum margin thickness:

1.2 mm (0.0472 in.)

Check the overall length of the valve.

Standard overall length:

103.95 to 104.35 mm (4.09 to 4.11 in.)

Minimum overall length:

103.45 mm (4.07 in.)

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 exhaust valve.

NOTICE:

Do not grind the valve so it becomes shorter than the minimum overall length.

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

Maximum deviation:

2.0 mm (0.0787 in.)

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

Standard Free Length:

46.20 mm (1.82 in.)

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

Standard tension:

301 to 332 N (31 to 34 kgf, 66.6 to 74.6 lbf) at 37.00 mm (1.46 in.)

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

Standard bush inside diameter:

8.010 to 8.030 mm (0.315 to 0.316 in.)

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

Standard oil clearance:

0.020 to 0.055 mm (0.000787 to 0.00217 in.)

Maximum oil clearance:

0.08 mm (0.00315 in.)

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

Standard bush inside diameter:

8.010 to 8.030 mm (0.315 to 0.316 in.)

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

Standard oil clearance:

0.035 to 0.070 mm (0.00138 to 0.00276 in.)

Maximum oil clearance:

0.10 mm (0.00394 in.)

Using a 45° carbide cutter, resurface the valve seats. Remove only enough metal to clean the seats.

Check the valve seating position.

1. Apply a light coat of Prussian blue to the valve face.
   

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

3. Prussian blue appears 360° around the entire valve face, the valve is concentric. If not, replace the valve.
   

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

5. Check that the seat contacts the middle of the valve face with the width below:
   

   Standard width:

   1.5 to 1.9 mm (0.0591 to 0.0748 in.)
   

Using a 45° carbide cutter, resurface the valve seats. Remove only enough metal to clean the seats.

Check the valve seating position.

1. Apply a light coat of Prussian blue to the valve face.
   

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

3. Prussian blue appears 360° around the entire valve face, the valve is concentric. If not, replace the valve.
   

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

5. Check that the seat contacts the middle of the valve face with the width below:
   

   Standard width:

   1.8 to 2.2 mm (0.0708 to 0.0866 in.)
   

   Text in Illustration

   *1

   Width

Using a micrometer, measure the lifter diameter.

Standard lifter diameter:

40.892 to 40.902 mm (1.6099 to 1.6103 in.)

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

Standard lifter bore diameter:

40.960 to 40.980 mm (1.6126 to 1.6134 in.)

Subtract the lifter diameter measurement from the lifter bore diameter measurement.

Standard oil clearance:

0.058 to 0.088 mm (0.00238 to 0.00346 in.)

Maximum oil clearance:

0.10 mm (0.00394 in.)

Inspect the journal diameter of the camshaft.

1. Using a micrometer, measure the journal diameter of the camshaft for the camshaft bearing.
   

   Standard Journal Diameter:

   Item	Specified Condition
   No. 1 journal	34.969 to 34.985 mm (1.3767 to 1.3774 in.)
   Other journals	27.969 to 27.985 mm (1.101 to 1.102 in.)

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

Check the oil clearance.

1. Clean the bearing caps and journals.
   

2. Check the bearings for flaking and scoring.
   If the bearings are damaged, replace the bearing caps and cylinder head as a set.
   

3. Install the bearings to the bearing caps and cylinder head.
   

4. Place the camshaft on the cylinder head.
   

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

   Text in Illustration

   *1	Plastigage

6. Install the bearing caps (LandCruiser RM00000123A00BX_01_0001.html).
   

   NOTICE:

   Do not turn the camshaft.

7. Remove the bearing caps (LandCruiser RM00000123D00BX_01_0008.html).
   





8. Measure the Plastigage at its widest point.
   

   Standard oil clearance:

   0.022 to 0.074 mm (0.000866 to 0.00291 in.)
   

   Maximum oil clearance:

   0.10 mm (0.00394 in.)
   

   Text in Illustration

   *1	Plastigage

   If the oil clearance is more than the maximum, replace the cylinder head sub-assembly. If necessary, grind or replace the camshaft.
   

9. Completely remove the Plastigage.
   

10. Remove the camshaft.
    

Check the thrust clearance.

1. Install the camshaft.
   





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

   Standard thrust clearance:

   0.080 to 0.280 mm (0.00351 to 0.0110 in.)
   

   Maximum thrust clearance:

   0.35 mm (0.0138 in.)
   

   If the thrust clearance is more than the maximum, replace the No. 1 bearing. If necessary, replace the camshaft.