To adjust (check) the clearances, set the crankshaft to position "I", corresponding to the start of fuel injection into the 1st cylinder, while switching off the fuel supply by fully depressing the idle drive lever.
Place the flywheel lock (Fig. 2, a) in the lower position as shown in Fig. 2, b.
Remove the cover of the front hatch 1 of the clutch housing (Fig. 5).
Inserting a pry bar into the holes 2 in the flywheel, turn the crankshaft in the direction of rotation until the lock engages with the flywheel under the action of the spring.
The position of the marks on the end face of the injection timing advance coupling body and the flange of the driving half-coupling of the fuel injection pump drive (Fig. 3) must coincide and be in the upper position.
If the marks are not in the upper position, disengage the lock, turn the crankshaft one revolution until the crankshaft is locked again.
Place the lock in the upper fixed position.
Turn the crankshaft in the direction of rotation (counterclockwise when viewed from the flywheel side) by an angle of 60° (turning the flywheel by the distance between two adjacent holes corresponds to turning the crankshaft by 30°), i.e. to the "I" position.
In this crankshaft position, the clearance in the valves of the 1st and 5th cylinders is checked (valves closed, valve pushrods turn easily by hand).
Use a torque wrench to check the tightening torque of the nuts securing the rocker arm stands of the adjustable valves (Mcr = 4.2 ÷ 5.4 kgf·m).
Measure with a feeler gauge the clearance between the rocker arm tips and the valve stem ends of the 1st and 5th cylinders.
With properly adjusted clearances, a 0.20 mm feeler gauge for the intake valve and a 0.30 mm feeler gauge for the exhaust valve should enter freely, while a 0.25 mm feeler gauge for the intake and a 0.35 mm feeler gauge for the exhaust should enter with resistance.
If necessary, adjust the required clearance as follows:
- using a valve adjustment tool or a spanner and screwdriver, loosen nut 2 (Fig. 4) of adjusting screw 1;
- insert the feeler gauge of the required thickness and, by turning the screw with a screwdriver, adjust the required clearance;
- while holding the screw with a screwdriver, tighten the nut and check the clearance.
The tightening torque of the adjusting screw nut should be 4.2-5.4 kgf·m.
To check the clearances in the remaining valves, set the crankshaft to positions "II", "III" and "IV", for this turn it by 180°, 260°, 540° respectively relative to the first crankshaft position, checking the valves of cylinders 4 and 2, 6 and 3, 7 and 8.
Install the clutch housing hatch cover and cylinder head covers in place.
Start the engine. With properly adjusted clearances, there should be no knocking in the valve mechanism.
Checking and tightening the cylinder head bolts
Unscrew the bolts securing the cylinder head covers and remove them.
On a cold engine or no earlier than 30 minutes after it has been stopped (if it was running), tighten the cylinder head bolts in three stages in the sequence shown in Fig. 1.
The bolt tightening torque should be: first stage 4-5 kgf·m, second stage — 12-15 kgf·m, third stage — 19-21 kgf·m (limit value).
