Remove the cylinder head cover (650.1003256 - complete).
Remove the injector harness from the bracket brackets
Disconnect the electrical wires from the injectors.
Remove the bracket for the injector harness (650.3724126).
Disconnect the coolant temperature sensor (3) (650.1130556) (see Fig. 1).
Remove the screw (1), remove the 1.-shaped adapter (2) and the cable bundle (see Fig. 21).
Remove the swivel bolt (310200) with two copper washers (312381) securing the fuel drain pipe from the head.
Remove the fuel drain pipe (650.1104346).
Remove 12 bolts (1) (see Fig. 2) fastening the racks of the rocker axle (650.1007108).
Remove rocker arms with axle and struts assembly (650.1007088).
Remove rocker bars (650.1007176).
Lay out the parts in the correct order.
Remove 14 M20 bolts (650.1003016) and 24 M14 bolts (650.1003017) securing the cylinder head.
Remove the cylinder head (see Fig. 3).
Remove the cylinder head gasket (650.1003210).
Fix the sleeves using tool 1462 (see Fig. 4).
Installing the YaMZ-650 cylinder head
1. Install the cylinder head gasket so that the manufacturer's mark is on top.
- 2. Check for center pins. (Use 2 capless screws (A) with a diameter of 14 mm, a length of 170 mm (see Fig. 5)).
- 3. Install the cylinder head.
- 4. Remove screws (A).
5. Install the cylinder head bolts and tighten in the order shown in Fig. 6.
Tighten in four steps using tools 2322 + 9777:
- - 1st trick: bolts (1 - 14) M20x1.5 - 215 mm torque Mcr = 200 Nm;
- - 2nd technique: bolts (15 - 38) M14x1.5 - 190 mm torque Mcr = 120 Nm;
- - 3rd method: loosen the M20 bolts, then tighten with a torque of Mcr = 100 ± 10 Nm and tighten by an angle of 180˚ ± 6˚;
- - 4th trick: loosen the M14 bolts, then tighten with a torque of Mcr = 80 ± 10 Nm and tighten by an angle of 100˚ ± 6˚.
Once the bolts have been tightened in the order shown, do not retighten the bolts in the future.
Lubricating bolts:
- - since the new bolts are already lubricated, no additional lubrication is required;
- - when reusing and subsequent use of bolts, lubricate the thread and under its head with Loctite 542 sealant.
Installation of rocker arms with axle and uprights assembly
- 1. Lubricate the seating surfaces with oil.
- 2. Install rocker bars.
- 3. Make sure that the alignment pins are present.
- 4. Install rocker axle.
5. Tighten the rocker arm strut bolts in the order shown and to the recommended torque (see Fig. 7):
- - pre-tighten, following the tightening torque Mcr = 20 ± 4 Nm;
- - finally tighten, observing the tightening order with a torque of Mcr = 40 ± 4 Nm plus an additional turn of 90˚ ± 6˚
- - check the tightening torque with a torque wrench Mcr = 100 ± 10 Nm.
Lubricating the bolts: Since the new bolts are already lubricated, no additional lubrication is required.
6. Install the injector harness bracket by tightening its fastening bolts to Mcr = 7.5 ± 1.5 Nm.
Adjustment of rockers
Checking and adjusting the clearances in the valve mechanism should be carried out on a cold engine or not earlier than two hours after it has been stopped.
To check and adjust the gaps, it is necessary to set the piston of the adjustable cylinder to the top dead center (TDC) position on the compression stroke when the intake and exhaust valves are closed.
It is recommended to check and adjust the gaps in accordance with the order of operation of the cylinders: 1 - 5 - 3 - 6 - 2 - 4.
Cylinders are numbered from the fan.
WARNING! TDC ON THE COMPRESSION STROKE CAN BE DETERMINED BY THE FREE TURNING “BY HAND” OF THE ROCKER ARMS OF THE INLET AND EXHAUST VALVES OF THE ADJUSTABLE CYLINDER. IF THE RODS ARE CLAMPED AND DO NOT TURN, THE CRANKSHAFT MUST BE ROTATED 360˚ (ONE TURN).
The gaps are checked using a feeler gauge, which must be inserted between the toe of the rocker arm and the stop of the traverse.
Gap value “A” (see Fig. 8) should be:
- - at the inlet 0.40 ± 0.05 mm,
- - at outlet 0.70 ± 0.05 mm.
Check with a torque wrench the tightening torque of the rocker arm strut mounting bolts (for tightening) and, if necessary, tighten them.
The tightening torque should be 80 - 100 Nm.
Adjust the clearances in the drive of the intake and exhaust valves of the 1st cylinder, for which you need:
1. Disconnect and unscrew the engine speed sensor from the flywheel housing (1) (see Fig. 9).
- 2. By rotating the crankshaft using a rotary device, in the direction of rotation, set the piston of the 1st cylinder to TDC on the compression stroke (1 position (see Fig. 10))
- 3. Loosen the locknut of the adjusting screw of the rocker arms of the intake and exhaust valves (alternately) and back out the screw by half a turn.
- 4. Insert a feeler gauge of the required thickness between the rocker toe and the stop surface of the yoke and, holding it in this position, turn in the adjusting screw so that the toe of the rocker comes into contact with the feeler gauge (adjustment is made for both intake and exhaust valves).
- 5. While holding the adjusting screw in this position, tighten the lock nut of the screw to a torque Mkr = 40 ± 8 Nm
- (during the subsequent check of the gaps, the probe with a thickness of 0.45 mm at the inlet and 0.75 mm at the outlet should enter with little effort (1 kgf), 0.35 mm thick at the inlet and 0.65 mm at the outlet - freely, without effort).
- 6. further, turning the crankshaft sequentially by 120˚ from position 1 (initial), adjust the clearances in the 5th, 3rd, 6th, 2nd and 4th cylinders in the same order, respectively.
- 7. Start the engine and listen to its work. With correctly adjusted clearances, there should be no knocking in the valve mechanism.