Cylinder Head Repair

GENERAL INFORMATION

Cleaning valve guides

Checking cylinder head mating surface flatness

Measuring cylinder head height.

A = 96 ± 0.25 mm

Warning.

Before removing the cylinder head and valve train,

measure cylinder compression and record the results. When disassembling the valve train, keep parts grouped separately.

and install them strictly in the same positions they occupied before disassembly.

Otherwise, the break-in of the parts will be disrupted..

Disassembly

PROCEDURE.

1. Valve train..

2. Unscrew the spark plugs..

Inspection

PROCEDURE.

Inspect the cylinder head gasket and mating surfaces for signs of coolant and oil leakage, gas blow-by and corrosion. If the gasket is defective, determine the cause.

– incorrect installation.

– loosened fastening or deformation of the cylinder head.

– missing dowels..

Clean.

Warning.

When using a power wire brush, wear

safety glasses to protect the eyes..

PROCEDURE.

1. Cylinder head. Remove all deposits down to bare metal. Do not

use a power wire brush on the mating surface.

head to cylinder block..

2. Valve guides, see Fig. Cleaning valve guides.

3. Threaded holes.

4. Remains of sealant in the spark plug holes.

Inspection

PROCEDURE.

1. Condition of the threads and heads, absence of cracks on the shanks of the cylinder head bolts.

Warning.

When installing the head, use only new cylinder head bolts.

2. Cylinder head for cracks, especially between the valve seats and in the

exhaust ports.

3. Top surface of the head for signs of corrosion, foreign inclusions in the material and porosity.

4. Deviation from flatness of the top surface of the head, as well as the mating surfaces for the intake and exhaust manifolds. Refer to Flatness Check illustration.

flatness of the cylinder head contact surface. If

distortion is present, replace the cylinder head.

5. Measure the cylinder head height. If the height is 95.75 mm or less, replace the head. Refer to Cylinder Head Height Measurement illustration.

6. Condition of all threaded holes. A damaged threaded hole can be

repaired using a threaded insert (helicoil).

7. Seating surfaces.

– coolant jacket plugs.

8. Valve guides.

Before repairing the valve seats, first check the condition and repair the valve guides, as they

center the valve stems in the head relative to the seats. Before measuring

the diameter and performing any repair work, thoroughly clean the guides. If worn, ream the guide bores to the

oversize repair dimension.

oversize repair dimension.

oversize repair dimension.

9. Valve seats for severe wear and pitting.

Valve seats can be repaired by grinding. To restore

the valve seats, use a special seat grinding machine. When operating, follow

the grinding machine manufacturer's instructions. If the seats have been ground, it is necessary to

also machine the valve face chamfers or replace the valves.

also machine the valve face chamfers or replace the valves.

Installation

PROCEDURE.

1. Spark plugs.

2. Valves and valve springs.

Warning.

To prevent damage, install the spark plugs after installing the cylinder

head.