Inspection

INSPECTION, CLEANING AND REPAIR OF CYLINDER HEAD COMPONENTS

1. CLEAN TOP OF PISTONS AND TOP OF CYLINDER BLOCK
(a) Turn the crankshaft and bring each piston to top dead center. Using a gasket scraper, remove all the carbon from the piston tops.
(b) Using a gasket scraper, remove all gasket material from the top of the block. Blow carbon and oil from the bolt holes.

WARNING: Protect your eyes when using compressed air.

2. REMOVE GASKET MATERIAL
Using a gasket scraper, remove all gasket material from the head and manifold surfaces.

CAUTION: Be careful not to scratch the surfaces.

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

CAUTION: Be careful not to scratch the head gasket on contact surface.

4. CLEAN VALVE GUIDE BUSHINGS
Using a valve guide brush and solvent, clean all the valve guide bushings.

5. CLEAN CYLINDER HEAD
Using a soft brush and solvent, thoroughly clean the head.

6. INSPECT CYLINDER HEAD FOR FLATNESS
Using a precision straight edge and thickness gauge, measure the surface contacting the cylinder block and manifold for warpage.
Maximum warpage: 0.10 mm (0.0039 in.)
If warpage is greater than maximum, replace the cylinder head.

7. INSPECT CYLINDER HEAD FOR CRACKS
Using a dye penetrant, check the combustion chamber, intake and exhaust ports, head surface and the top of the head for cracks. If cracked, replace the head.

8. CLEAN VALVES
(a) Use a gasket scraper to chip any carbon from the valve head.
(b) Using a wire brush, thoroughly clean the valve.

9. INSPECT VALVE STEMS AND GUIDE BUSHINGS
(a) Using a caliper gauge, measure the inside diameter of the valve guide.
Guide inside diameter: 6.010 - 6.030 mm (0.2366 - 0.2374 in.)

(b) Using a micrometer, measure the diameter of the valve stem.
Stem diameter:
Intake 5.970 - 5.985 mm (0.2350 - 0.2356 in.)
Exhaust 5.965 - 5.980 mm (0.2348 - 0.2354 in.)
(c) Subtract the valve stem measurement from the valve guide measurement.
Standard stem oil clearance:
Intake 0.025 - 0.060 mm (0.0010 - 0.0024 in.)
Exhaust 0.030 - 0.065 mm (0.0012 - 0.0026 in.)
Maximum stem oil clearance:
Intake 0.08 mm (0.0031 in.)
Exhaust 0.10 mm (0.0039 in.)
If the clearance is greater than maximum, replace the valve and guide.

10. IF NECESSARY, REPLACE VALVE GUIDE BUSHINGS
(a) Insert an old valve wrapped with tape into the valve guide bushing and break off the valve guide bushing by hitting it with a hammer.

CAUTION: Be careful not to damage the lifter hole.

(b) Gradually heat the cylinder head to approx. 90°C (1 94°F).

(d) Using a caliper gauge, measure the valve guide bore of the cylinder head.

(e) Select a new valve guide bushing.
If the valve guide bushing bore of the cylinder head is more than 11.027 mm (0.4341 in.), machine the bore to the following dimensions.
Rebored valve guide bushing bore dimension: 11.050 - 11.077 mm (0.4350 - 0.4361 in.)

(f) Gradually heat the cylinder head to approx. 90°C (194°F).
(g) Using SST and hammer, drive in a new valve guide bushing until the snap ring makes contact with the cylinder head. SST 09201-70010

(h) Using a sharp 6 mm (0.24 in.) reamer, ream the valve guide bushing to obtain standard specified clearance (See page EM-53) between the valve guide bushing and new valve.

11. INSPECT AND GRIND VALVES
(a) Grind the valve only enough to remove pits and carbon.
(b) Check that the valve are ground to the correct valve face angle.
Valve face angle: 44.5°

(c) Check the valve head margin thickness.
Standard margin thickness: 1.3 mm (0.051 in.)
Minimum margin thickness: 0.5 mm (0.020 in.)
If the valve head margin thickness is less than minimum, replace the valve.

(d) Check the valve overall length.
Standard overall length: 98.15 mm (3.8642 in.)
Minimum overall length: 97.75 mm (3.8484 in.)
If the valve overall length is less than minimum, replace the valve.

(e) Check the surface of the valve stem tip for wear. If the valve stem tip is worn, regrind it with grinder or replace the valve if necessary.

CAUTION: Do not grind off more than minimum overall length

12. INSPECT AND CLEAN VALVE SEATS
(a) Using a 45° cutter, resurface the valve seats. Remove only enough metal to clean the seats.

(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° around the face, the valve is concentric. If not, replace the valve.
- If blue appears 360° 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 with the following width: 1.0 - 1.4 mm (0.039 - 0.055 in.) If not, correct the valve seat as follows:
- If seating is too high on the valve face use 30° and 45° cutters to correct the seat.

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

(d) Hand-lap the valve and valve seat with an abrasive compound.

13. INSPECT VALVE SPRINGS
(a) Using a steel square, measure the squareness of the valve springs.
Maximum squareness: 1.5 mm (0.059 in.)
If squareness is greater than maximum, replace the valve spring.

(b) Using calipers, measure the free length of the valve spring.
Free length: 41.64 mm (1.6394 in.)
If the free length is not within specification, replace the valve spring.

(c) Using a spring tester, measure the tension of the valve spring at the specified installed length.
Installed tension: 16.0 kg (35 lb, 157 N) at 35.0 mm (1.378 in.) If the installed tension is not as specified, replace the valve spring.

14. INSPECT CAMSHAFT AND BEARING CAPS
(a) Place the camshaft on V-blocks and, using a dial gauge, measure the circle runout at the center journal.
Maximum circle runout: 0.03 mm (0.0012 in.)
If the circle runout is greater than maximum, replace the camshaft.

(b) Using a micrometer, measure the cam lobe height.
Standard cam lobe height: 38.36 mm (1.5102 in.)
Minimum cam lobe height: 38.00 mm (1.4961 in.)
If the cam lobe height is less than minimum, replace the camshaft.

(c) Using a micrometer, measure the journal diameter.
Standard diameter:
NO.1 26.949 - 26.965 mm (1.0610 - 1.0616 in.)
NO.2 - NO.7 26.888 - 26.975 mm (1.0586 - 1.0620 in.)
If the journal diameter is less than specified, replace the camshaft.

15. INSPECT CAMSHAFT OIL CLEARANCE
(a) Clean the bearing caps and camshaft journal.
(b) Place the camshaft in the cylinder head.
(c) Lay a strip of Plastigage across each journal.

(d) Place the bearing caps with the top of the number on the cap pointing toward the front and in numerical order from the front side.
(e) Install and torque the cap bolts gradually in the sequence shown in the figure.
Torque: 200 kg-cm (14 ft-lb, 20 N.m)

NOTE: Do not turn the camshaft while the Plastigage is in place.

(f) Remove the caps and measure the Plastigage at its widest point.
Standard oil clearance:
NO.1 0.035 - 0.072 mm (0.0014 - 0.0028 in.)
NO.2 - NO.7 0.025 - 0.093 mm (0.0010 - 0.0037 in.)
Maximum oil clearance: 0.13 mm (0.0051 in.)
If clearance is greater than maximum, replace the cylinder head and/or camshaft.
(g) Clean out the pieces of Plastigage from the bearing caps and journals.

16. INSPECT CAMSHAFT THRUST CLEARANCE
(a) Clean and install the camshaft and bearing caps.
(b) Using a dial gauge, measure the thrust clearance while moving the camshaft back and forth.
Standard thrust clearance: 0.08-0.19 mm (0.0031 - 0.0075 in.)
Maximum thrust clearance: 0.30 mm (0.0118 in.)
If clearance is greater than maximum, replace the camshaft and/or cylinder head.

17. INSPECT VALVE LIFTER OIL CLEARANCE
(a) Using a micrometer, measure the diameter of the valve lifter.

(b) Using a dial indicator, measure the inside diameter of the cylinder head bore.
(c) Subtract the valve lifter measurement from the cylinder head bore.
Standard oil clearance: 0.015 - 0.046 mm (0.0006 - 0.0018 in.)
Maximum oil clearance: 0.10 mm (0.0039 in.)
If clearance is greater than maximum, replace the cylinder head and/or valve lifter.

18. INSPECT INTAKE, EXHAUST MANIFOLD AND INTAKE CHAMBER
Using a precision straight edge and feeler gauge, check the surfaces contacting the cylinder head or intake manifold for warpage.
Maximum warpage:
Intake manifold 0.10 mm (0.0039in.)
Exhaust manifold
7M-GE 0.75 mm (0.0295in.)
7M-GTE 0.50 mm (0.0197in.)
Intake chamber 0.10 mm (0.0039in.)

INSPECTION OF INTAKE AIR CONTROL SYSTEM (7M-GE only)
1. CHECK AIR CONTROL VALVE OPERATION
With 400 mmHg (15.75 in.Hg, 53.3 kPa) of vacuum applied to the actuator, check that the control valve moves smoothly to the fully closed position.
If not adjust with the adjusting screw.

2. CHECK VACUUM TANK BY BLOWING AIR INTO EACH PIPE
(a) Check that air flows from pipe B to A.
(b) Check that air does not flow from pipe A to B.

(c) Apply 500 mmHg (19.69 in.Hg, 66.7 kPa) of vacuum to pipe B and check that there is no change in vacuum after one minute. If there is a change, replace the vacuum tank.

3. CHECK VACUUM CIRCUIT CONTINUITY IN THE VSV BY BLOWING AIR INTO PIPE
(a) Connect the VSV terminals to the battery terminals as illustrated.
(b) Blow into pipe E and check that air comes out of the pipe G.

(c) Disconnect the battery.
(d) Blow into pipe E and check that air comes out of the air filter. If a problem is found, replace the VSV.