Pic. 2.249. Cylinder head, valves and valve springs
Withdrawal
Drain the coolant and disconnect the upper radiator hose.
Disconnect the air ducts and crankcase ventilation hose.
Disconnect vacuum, fuel and water hoses.
Remove the intake manifold.
Disconnect high voltage wires from spark plugs. Pull on the protective cap, not the wires themselves.
Remove the ignition coil.
Remove the timing belt covers.
Remove the timing belt and camshaft sprockets.
Remove the exhaust manifold guards and the exhaust manifolds themselves.
Remove the water pump pulley and valve covers.
Remove camshafts.
Loosen the cylinder head bolts in two or three steps (tool head 12 mm). Remove the cylinder head.
Remove the remnants of the old gasket from the mating surfaces of the head and cylinder block.
Note. Take steps to prevent dirt from entering the crankcase.
Checking the cylinder head
Check the cylinder head for cracks, damage and signs of coolant leakage. If cracks are found, replace 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 with compressed air.
Pic. 2.250. Checking the flatness of the mating surface of the cylinder head
Check up flatness of a mating surface of a head of cylinders in the directions shown in drawing 2.250.
Non-flatness of the mating surface of the cylinder head:
Nominal value: less than 0.03 mm.
Limit value: 0.05 mm.
Checking the valve guides
Pic. 2.251. Checking clearance between valve guide and valve stem
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. 2.251).
Gap between guide and valve stem.
Rated value:
- intake valve: 0.02–0.05 mm;
- exhaust valve: 0.035–0.065 mm.
Maximum allowable value:
- intake valve: 0.10 mm;
- outlet valve: 0.15 mm.
Checking valves
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» valve stem is dented or there is significant wear, replace the valve.
Pic. 2.252. Valve Test Diagram
Check the condition of the valve chamfer, repair if necessary (pic. 2.252).
Replace the valve if the valve disc thickness is less than the limit
Valve plate thickness.
Rated value:
- Inlet valve - 1.0 mm;
- Exhaust valve - 1.3 mm.
Maximum allowable value:
- Inlet valve - 0.5 mm;
- Exhaust valve - 0.8 mm.
Pic. 2.253. Valve seat contact test
Checking the valve springs
Check the free length of the valve spring. If the length of the spring is less than the limit, replace the valve spring.
Pic. 2.254. Valve Spring Test Diagram
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 (pic. 2.254).
valve spring.
Rated value:
- spring length in a free state - 42.5 mm;
- spring length under load 21.9 kg - 35.0 mm;
- spring deflection (non-perpendicularity) - 1.5°or less.
Maximum allowable value:
- spring length in a free state - 41.5 mm;
- spring length under load 21.9 kg - 34.0 mm;
- spring deflection (non-perpendicularity) - 3°.
Valve seat rebuild
Check the valve seat for signs of overheating and uneven contact with the valve disc's obturator chamfer. If necessary, either repair or replace the valve seat.
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.
Pic. 2.255. Valve seat rebuild
Restoration of the valve seat is carried out with a special tool (cutters or on machine tools). After restoring the valve seat, the valve and valve seat must be lapped using lapping paste (pic. 2.255).
Valve Guide Replacement
With a special tool (mandrel for installing the guide bushing 09221-29000) Press the old valve guide out of the cylinder head towards the gasket surface.
Pic. 2.256. Valve guide replacement diagram
Bore the cylinder head bore to install the correct oversize valve guide (increased diameter) (pic. 2.256).
With a special tool (mandrel for installing the guide bushing 09221-29000 (A), 09222-22000 (IN)) press in the new valve guide.
The guide sleeve should be pressed in 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.
After installing the valve guide, insert the new valve and check that the clearance between the valve guide and the valve stem is correct.
Pic. 2.257. Valve guide length
After replacing the valve guide, check that the valve is properly seated in the seat. Rework valve seat if necessary (pic. 2.257).
Note. Do not install an old size guide, always bore the head to the next overhaul of the guide.
Valve seat replacement
Pic. 2.258. Valve seat replacement diagram
Cut out the valve seat to be replaced, the remaining amount of metal is indicated in Figure 2.258.
Pic. 2.259. Scheme of boring holes in the cylinder head
Bore a hole in the cylinder head to install a valve seat of the appropriate repair size (increased diameter) (pic. 2.259).
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 face width:
- inlet - 1.1–1.5 mm;
- release - 1.3–1.7 mm.
Assembly
Install the valve spring seats.
Pic. 2.260. Scheme of installation of 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. 2.260).
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. 2.261. 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. 2.261).
Pic. 2.262. Installation of crackers
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 (pic. 2.262).
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.
Pic. 2.263. Cylinder head gasket identification mark
Install the cylinder head gasket on the cylinder block with the identification mark facing up (to the cylinder head) (pic. 2.263).
Note. Do not apply sealant to the gasket.
Tighten bolts of fastening of a head of cylinders the nominal moment in the order shown in drawing 2.264.
Pic. 2.264. Tightening the cylinder head bolts
When tightening the bolts (tool head 12 mm) combined tightening method is used (moment + angular adjustment) (pic. 2.264).
Pic. 2.265. The order of tightening the cylinder head bolts
Pic. 2.266. Scheme of turning bolts of fastening of a head of the block of cylinders
Tightening torque of the cylinder head bolts: 25 Nm + (58–62°) + (43–47°) (pic. 2.266).