Inspection Cleaning And Repair Of Cylinder Head Components

1. CLEAN TOP SURFACES OF PISTONS AND CYLINDER BLOCK

(a) Turn the crankshaft and bring each piston to top dead center (TDC). Using a gasket scraper, remove all the carbon from the piston top surface.

(b) Using a gasket scraper, remove all the gasket material from the top surface of the cylinder block.

(c) Using compressed air, blow carbon and oil from the bolt holes.

CAUTION: Protect your eyes when using high-com-pressed air.

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2. CLEAN CYLINDER HEAD

A. Remove gasket material

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

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

B. Clean combustion chambers

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

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

C. Clean valve guide bushings

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

D. Clean cylinder head

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

3. INSPECT CYLINDER HEAD

A. Inspect for flatness

Using precision straight edge and feeler gauge, measure the surfaces contacting the cylinder block, T-VIS valve and exhaust manifold for warpage.

Maximum warpage:

Cylinder block side 0.20 mm (0.0079 in.)

Exhaust manifold side 0.30 mm (0.0118 in.)

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

B. Inspect for cracks

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

If cracked, replace the cylinder head.

4. CLEAN VALVES

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

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

5. INSPECT VALVE STEMS AND GUIDE BUSHINGS

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

Bushing inside diameter:

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

Valve stem diameter:

(c) Subtract the valve stem diameter measurement from the guide bushing inside diameter measurement.

Standard oil clearance:

Maximum 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 bushing.

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6. IF NECESSARY, REPLACE VALVE GUIDE BUSHINGS

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. Remove the snap ring.

HINT: Wrap the tape approx. 13 mm (0.51 in.) from the valve stem end.

NOTICE: Be careful not to damage the valve lifter hole.

(b) Gradually heat the cylinder head to 80 -100°C (176 - 212°F).

(c) Using SST and a hammer, tap out the guide bushing.

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(d) Using a caliper gauge, measure the bushing bore diameter of the cylinder head.

Both intake and exhaust

Bushing bore diameter mm(in.)

Bushing size

10.988-11.006 (0.4326 - 0.4333)

Use STD

11.038 - 11.056 (0.4346 - 0.4353)

Use 0/S 0.05

(e) Select a new guide bushing (STD size or O/S 0.05).

If the bushing bore diameter of the cylinder head is greater than 11.006 mm (0.4333 in.), machine the bushing bore to the following dimension:

If the bushing bore diameter of the cylinder head is greater than 11.056 mm (0.4353 in.), replace the cylinder head.

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(f) Gradually heat the cylinder head to 80 -100°C (176 - 212°F).

(g) Using SST and a hammer, tap in a new guide bushing until the snap ring makes contact with the cylinder head.

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(h) Using a sharp 6 mm reamer, ream the guide bushing to obtain the standard specified clearance (See page EM-75) between the guide bushing and valve stem.

7. INSPECT AND GRIND VALVES

(a) Grind the valve enough to remove pits and carbon.

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

Valve face angle: 44.5°

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Margin Thickness

(c) Check the valve head margin thickness.

Standard margin thickness: 0.8 - 1.2 mm

Minimum margin thickness: 0.5 mm (0.020 in.)

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

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(d) Check the valve overall length.

Standard overall length:

Intake 105.50 mm (4.1535 in.) Exhaust 99.55 mm (3.9193 in.)

Minimum overall length:

Intake 104.80 mm (4.1260 in.) Exhaust 98.85 mm (3.8917 in.)

If the 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, resurface the tip with a grinder or replace the valve.

NOTICE: Do not grind off more than the minimum.

8. INSPECT AND CLEAN VALVE SEATS

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

(b) Check the valve seating position.

Apply a thin coat of prussion blue (or white lead) to the valve face. Lightly press the valve against the seat. Do not rotate the valve.

(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 face are concentric. If not, resurface the seat.

• Check that the seat contact is in the middle of the valve face with the following width:

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If not, correct the valve seats as follows:

(1) If the seating is too high on the valve face, use 30° and 45° cutters to correct the seat.

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(2) If the seating is too low on the valve face, use 75° and 45° cutters to correct the seat.

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

(e) After hand-lapping, clean the valve and valve seat.

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9. INSPECT VALVE SPRINGS

(a) Using a steel square, measure the squareness of the valve spring.

Maximum squareness: 2.0 mm (0.079 in.)

If squareness is greater than maximum, replace the valve spring.

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

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

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

Installed tension:

20.5 - 24.1 kg (45.2 - 53.1 lb, 201 - 236 N) at 34.4 mm (1.354 in.)

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

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10. INSPECT CAMSHAFTS AND BEARINGS

A. Inspect camshaft for runout

(a) Place the camshaft on V-blocks.

(b) Using a dial indicator, measure the circle runout at the center journal.

Maximum circle runout: 0.06 mm (0.0024 in.)

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

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B. Inspect cam lobes

Using a micrometer, measure the cam lobe height.

Standard cam lobe height: 41.010 - 41.110 mm

Minimum cam lobe height: 39.90 mm (1.5709 in.)

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

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C. Inspect camshaft journals

Using a micrometer, measure the journal diameter.

Journal diameter: 26.959 - 26.975 mm (1.0614-1.0620 in.)

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

D. Inspect camshaft bearings

Check the bearings for flaking and scoring.

If the bearings are damaged, replace the bearing caps and cylinder head as a set.

E. Inspect camshaft journal oil clearance

(a) Clean the bearing caps and camshaft journals.

(b) Place the camshafts on the cylinder head.

(c) Lay a strip of Plastigage across each of the camshaft journals.

(d) Install the bearing caps.

NOTICE: Do not turn the camshaft.

(e) Remove the bearing caps.

(f) Measure the Plastigage at its widest point

Standard oil clearance: 0.025 - 0.062 mm

Maximum oil clearance: 0.08 mm (0.0031 in.)

If the oil clearance is greater than maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.

(g) Completely remove the Plastigage.

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F. Inspect camshaft thrust clearance

(a) Install the camshafts.

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

Standard thrust clearance: 0.120 - 0.240 mm

Maximum thrust clearance: 0.30 mm (0.0118 in.)

If the thrust clearance is greater than maximum, replace the camshaft. If necessary, replace the bearing caps and cylinder head as a set.

11. INSPECT VALVE LIFTERS AND LIFTER BORES

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

Lifter bore diameter: 28.000 - 28.021 mm

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(b) Using a micrometer, measure the lifter diameter.

Lifter diameter: 27.975 - 27.985 mm (1.1014 - 1.1018 in.)

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

Standard oil clearance: 0.015 - 0.046 mm

Maximum oil clearance: 0.07 mm (0.0028 in.)

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

12. INSPECT INTAKE AND EXHAUST MANIFOLDS (Intake manifold)

Using precision straight edge and feeler gauge, measure the surface contacting the T-VIS valve for warpage.

Maximum warpage: 0.20 mm (0.0079 in.)

If warpage is greater than maximum, replace the intake manifold.

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(Exhaust manifold)

Using precision straight edge and feeler gauge, measure the surface contacting the cylinder head for warpage.

Maximum warpage: 0.20 mm (0.0079 in.)

If warpage is greater than maximum, replace the exhaust manifold.

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