Removing
The cylinder head can be removed without removing the engine.
A defective cylinder head gasket is identified by loss of power, low coolant level, and presence of coolant in the engine oil.
Disconnect the wire «masses» from the battery.
Drain the coolant.
Remove the air filter.
Remove the alternator support from the cylinder head.
Disconnect the water hoses from the cylinder head and from the carburetor.
Disconnect the accelerator cable, do not remove the cable latch.
Remove the vacuum brake booster hose.
Mark with adhesive tape and disconnect the fuel pipes from the fuel collector.
Disconnect from carburetor (if it's a carbureted engine) electric wires.
Unscrew the heat sink from the collector.
Remove the exhaust pipe from the exhaust manifold.
Remove the top casing of a gear belt.
Release the tension roller and remove the toothed belt from the camshaft sprocket.
Tag and disconnect the electrical wires from the oil pressure switch and from the temperature sensor.
Disconnect the spark plug wires.
Disconnect the vacuum hose going to the ignition distributor from the carburetor.
Remove the cylinder head cover.
Loosen the vacuum hose clamp on the head of the block.
Loosen the block head bolts with an internal polyhedron head bolt wrench (e.g. HAZET 990 SI9-12).
Attention! Loosen the bolts in the reverse order of their numbering (pic. 169).
Remove the cylinder head, cylinder head gasket and place the cylinder head on two pieces of wood.
Installation
Before installation, remove the seal residues from the mating plane of the head and cylinder block with an appropriate scraper. Keep dirt out of the holes in the cylinder block.
Check the head with a steel ruler for warping.
Flatness deviation should not exceed 0.1 mm.
Permissible size for processing the cylinder head: the minimum permissible height measured between the plane of the junction of the block head with the cylinder block and the plane of installation of the valve cover is no more than 132.6 mm.
Check for cracks in the cylinder head between the valve seats or between the valve seat and the first thread of the spark plug hole. With a crack width of less than 0.5, the head
unit can continue to be used or repaired without reducing its service life.
Be sure to replace the cylinder head gasket.
Inscription «oben» («top») should point towards the cylinder head, fit the cylinder head gasket without sealing compound.
Make guide pins for centering the cylinder head by sawing off the heads of the old cylinder head bolts and cutting slots for a screwdriver.
Screw guide pins into holes 8 and 10 (see fig. 169).
Rotate the crankshaft by the crankshaft pulley until all pistons are approximately the same height.
Install the cylinder head.
Install and hand tighten the remaining 8 head bolts.
Unscrew the guide pins with a screwdriver, insert and tighten the remaining 2 head bolts by hand.
Attention! Cylinder head bolts must be tightened very carefully. Cylinder head bolts are tightened with a cold engine.
The cylinder head bolts are tightened in four passes. On each pass, the cylinder head bolts are tightened in sequence from 1 to 10 (see fig. 169):
- 1st pass: with torque wrench up to 40 Nm;
- 2nd pass: with torque wrench up to 60 Nm;
- 3rd pass: 1/4 turn (90 degrees) hard key without stopping;
- 4th pass: 1/4 turn (90 degrees) hard key without stopping.
Estimate the angle to the gate of the bolts. Place the key along the axis of the head of the block and turn it in one pass to the position of the key or across the axis of the head (90 degrees), or along the axis of the head on its other side (180 degrees).
Further assembly is carried out in the reverse order of disassembly.
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