Pic. 2.122. Cylinder head and valves
Disassembly
Pic. 2.123. The order of unscrewing the cylinder head bolts
With a special tool (key 09221-32001) turn away bolts of fastening of a head of cylinders in the order specified in drawing 2.123.
Pic. 2.124. Breadcrumbs extraction
With a special tool (valve spring compressor tool 09222-28000 and adapter 09222-28100) compress the spring and remove the crackers. Remove the valve spring cap, valve spring, valve spring seat and valve (pic. 2.124).
Note. Keep the parts for each valve separately as a set to avoid confusion during installation.
Pic. 2.125. Removing oil seals
With a special tool (oil seal remover 09222-29000) remove oil seals (pic. 2.125).
Note. Re-installation of valve stem seals is not allowed.
Checking the cylinder head
Check the cylinder head for cracks, damage and signs of coolant leakage. If cracks are found, replace the cylinder head.
Pic. 2.126. Cleaning the surface of the cylinder head
Completely clean the cylinder head of scale, carbon deposits and remnants of the old sealant and gasket. Clean the oil passages, blow them out with compressed air (pic. 2.126).
Pic. 2.127. Scheme for checking the flatness of the mating surface of the cylinder head
Check the flatness of the mating surface of the cylinder head in the directions shown in the figure. If the flatness exceeds the limit in any direction, either replace the cylinder head or regrind the mating surface of the cylinder head (pic. 2.127).
The values of non-flatness of the mating surface of the cylinder head are given below.
Nominal value: less than 0.03 mm.
Limit value: 0.2 mm.
Checking valves
Pic. 2.128. Valve cleaning
Use a wire brush to thoroughly clean the valve (pic. 2.128).
Pic. 2.129. Valve Test Diagram
Check each valve for wear, damage, and deformation of the poppet and area «B» valve stem. Replace valve if necessary. If at the end «A» If the valve stem is dented or there is significant wear, refinish the end of the valve stem if necessary. The thickness of the layer to be removed during mechanical processing of the end of the valve stem should be minimal. Also, chamfer the valve seat (pic. 2.129).
Replace the valve if the thickness of its plate is less than the maximum allowable value.
Nominal valve disc thickness:
- inlet valve - 1.0 mm;
- exhaust valve - 1.5 mm.
Maximum allowable value:
- intake valve - 0.7 mm;
- exhaust valve - 1.0 mm.
Checking the valve springs
Pic. 2.130. Valve Spring Test Diagram
Check the free length of the valve spring. If the spring length is less than the limit, replace the valve spring (pic. 2.130).
Using a square, check the deviation of the spring axis from perpendicular to the supporting surface (non-perpendicularity). If the misalignment is greater than the limit, replace the valve spring.
Valve spring measurement ratings are shown below.
Spring free length: 45.82 mm.
Spring length under load 25.3 kg: 40.00 mm.
Spring axis deflection (non-perpendicularity): 1.5°or less.
The valve spring measurement limits are shown below.
Spring free length: 44.82 mm.
Spring axis deflection (non-perpendicularity): 4°.
Checking the valve guides
Pic. 2.131. Valve Guide Test Diagram
Check clearance between valve guide and valve stem (at several points along the length). If the clearance is greater than the limit, replace the valve guide (pic. 2.131).
The clearance values between the valve guide and the valve stem are shown below.
Rated value:
- intake valve - 0.020–0.047 mm;
- exhaust valve - 0.050–0.085 mm.
Maximum allowable value:
- intake valve - 0.10 mm;
- exhaust valve - 0.15 mm.
Valve seat rebuild
Pic. 2.132. Valve seat rebuild
Check the valve seat for signs of overheating and uneven contact with the valve disc's obturator chamfer. Repair or replace the valve seat if necessary. Check the valve guide for wear before rebuilding the valve seat. If the guide bushing is worn, replace it first and then rebuild the valve seat. Restoration of the valve seat is carried out with a special tool (cutters or on machine tools). The width of the closing chamfer of the valve seat must correspond to the nominal values and the contact patch must be located evenly in the center of the working chamfer of the valve disc. After restoring the seat, the valve and seat must be lapped using lapping paste (pic. 2.132).
Valve seat replacement
Pic. 2.133. Residual amount of metal when machining a replaceable valve seat
Cut out the valve seat to be replaced, the remaining amount of metal is indicated in Figure 2.133.
Bore a hole in the cylinder head to install a valve seat of the appropriate repair size (increased diameter).
Heat the cylinder head to approximately 250°C and press the oversize seat into the cylinder head.
Lappe the valve to the new seat using lapping paste.
Valve seat obturator width: 0.9–1.3 mm.
Valve guide replacement
Pic. 2.134. Pressing out the old valve guide
With a special tool (mandrel for installing the guide bushing 09221-22000А) press the old valve guide out of the cylinder head towards the gasket surface (pic. 2.134).
Bore the cylinder head bore to install the correct oversize valve guide (increased diameter).
Pic. 2.135. The difference in the length of the guide sleeves for the intake and exhaust valves
With a special tool (mandrel for installing the guide bushing 09221–22000B) Press in the new valve guide from the side of the camshaft bed. Pay attention to the difference in the length of the guide bushings for the intake and exhaust valves (pic. 2.135).
After installing the valve guide, insert the new valve and check that the gap between the valve guide and the valve stem is correct.
After replacing the valve guide, check that the valve is properly seated in the seat. Rework the valve seat if necessary.
Assembly
Install the valve spring seats.
Note. Thoroughly clean all parts before assembly. Apply engine oil to all rubbing and rotating parts.
Pic. 2.136. Installing the valve stem seal
With a special tool (mandrel for installing the valve stem seal 09222-22001) with a light blow, install the oil scraper cap in place (pic. 2.136).
Note. Reuse of valve stem seals is not allowed.
Note. Improper installation of the valve stem seal can result in oil leaks through the valve guide.
Lubricate the valve stem with engine oil. Insert the valve into the valve guide. Do not apply force when passing the valve stem through the valve stem seal. After installing the valve, check the smoothness of its movement.
Pic. 2.137. Valve spring installation diagram
Install the valve spring so that the painted coil of the spring is located near the spring seat (up), and then install the valve spring cap (pic. 2.137).
With a special tool (valve spring compressor tool 09222-28000 and adapter 09222-28100) compress the valve spring and install the crackers. Before removing the special tool after installing the valve, check that the nuts are securely installed.
Note. When compressing the valve spring, make sure that the spring plate does not touch the valve stem seal.
Clean the mating surfaces for the gasket on the cylinder head and cylinder block.
Check that the cylinder head gasket identification marks match the specifications.
Install the cylinder head gasket on the cylinder block with the identification mark facing up (to the cylinder head).
Before installing the cylinder head bolts, measure their length.
Maximum bolt length: 99.4 mm.
Pic. 2.138. The order of tightening the cylinder head bolts
Tighten bolts of fastening of a head of cylinders the nominal moment in the order shown in drawing 2.138.
Tightening torque with replacement of head parts, block or head bolts): 63 Nm + loosen all bolts + 20 Nm + 90°+90°Without changing parts: 20 Nm + 90°+90°.