Repair of the cylinder head YaMZ-650

Disassembly of the cylinder head (guided by Fig. 1)

1. Unscrew the nuts (311442) securing the fuel supply fittings to the injectors

2. Remove the fuel supply fittings to the injectors (650.1112154).

3. Loosen the bolts (a) (300144) (see Fig. 2) fastening the injector brackets.

Removing YaMZ-650 injectors

4. Remove the injector mounting brackets (6) (650.1112163) (see Fig. 2).
5. Remove nozzles (c) (650.1112010) (see Fig. 2).
6. Remove copper washers (312383).

Removing the coolant drain box from the YaMZ-650 cylinder head

7. Remove the 7 cylinder head coolant drain box bolts (a) (310022) (see Fig. 3).
8. Remove the coolant drain box from the head (17).
9. Remove the gasket (18) from the coolant drain box.

Removing YaMZ-650 valves

10. Compress the springs using tool 9838 (see Fig. 4).
11. Remove breadcrumbs (25).
12. Remove the plates (24) and springs (21, 22).
13. Remove spring washers (23).
14. Remove the valves (26, 27) and arrange them in order.
15. Remove the valve cups (13).
16. Remove the valve guides (14, 15)
17. Weld a washer to the valve seat.
18. Push the seats (19, 20) out of the head.
19. Cut internal thread M26x1.5 mm in nozzle cups

Removing the YaMZ-650 nozzle cup

20. Remove nozzle cups (12) using tool 1205 (see Fig. 5).
21. Remove O-ring (11). Injector cups must be replaced with the cylinder head removed

Disassembly of rocker arms with axle and uprights. (See Fig. 1)

1. Pull out the guide bush (1).
2. Remove pins (5).
3. Remove rocker arms (2), struts (3) and springs (4).
4. If necessary, remove the plugs (7, 8).

Assembly of rocker arms with axle and uprights. (See Fig. 1)

1. Install plugs (7, 8) using Loctite 542 sealant.
2. Lubricate and install the uprights (3), rocker arms (2) and springs (4).
3. Set pins (1, 5).

Cylinder head cleaning.

(see Fig.1) Clean the cylinder head if necessary, remove the plugs (9, 10, 16) to remove carbon deposits.

Checking the cylinder head and MGR parts. (See Appendix B)

Checking the cylinder head for leaks YaMZ-650

1. Check the bearing surface of the cylinder head for the gasket.
2. Check the tightness of the cylinder head before installation.

Attach tool 2549 with 6 bar air pressure, immerse the head in hot water (80˚ C) and make sure there are no bubbles (see Fig. 6).

3. Check spring calibration.
4. Check radial clearance between valve and guide.
5. Check valve clearance and protrusion.

Dimensions and tolerances of the YaMZ-650 cylinder head

Cylinder head dimensions and tolerances

Dimensions and tolerances of the YaMZ-650 cylinder head

Cylinder head assembly

Install stubs:

Checking and installing stubs

1. Install plugs (9, 16) (see Fig. 1) using tools 3016 + 2363 25 mm.
2. Install the plug (10) (see Fig. 1) using tool 3016 + 2363 42 mm.
3. When installing plugs, use Loctite 542 sealant.
4. Check for recess “A” = 1.5 ± 0.5 mm (see Fig. 9)

Injector cup setting:

1. Replace the O-ring (11) (see Fig. 1).
2. Lubricate the nozzle cup with grease.
3. Replace the nozzle cup (12) (see Fig. 1).

Installing the YaMZ-650 nozzle cup

4. Install tool 2556.
5. Flare at “A” (see Fig. 10a) using tool 1220.
6. Remove tool 1220 using tool 1205 (see Fig. 10B)
7. Remove tool 2556
8. Check tightness.

Installing the valve guides:

Installation of YaMZ-650 valve guides

1. Lubricate the guide bushings with grease.
2. Press in the inlet (1) and outlet (2) valve guides using tool 2539 and a press (see Fig. 11).
After replacing the guide bushings, the valve seats are lapped. Lapping after seating.

Install valve seats:

Installation of YaMZ-650 valve seats

1. Cool valve seats in liquid nitrogen or freezer for approximately 12 hours.
2. Install the valve seats using tool 1332 and a press (see Fig. 12).

Valve seat lapping:

Grinding of YaMZ-650 valve seats

Before lapping the seats, check the condition of the valve guides. Replace if required.

Technique:

- valve guides should ensure tool centering.
- to determine the amount of metal to be removed, take into account the "R" values of the valve sinking; machine the seating surface "P" using tool 9732, respecting the angle "A":
- at the inlet 60˚,
- on release 45˚

Depending on the equipment/tool used, the angles are indicated either in relation to the plane of the junction of the cylinder head with the gasket, or in relation to the valve axis.

Installation of valves (see Fig. 1):

Removing the YaMZ-650 cylinder head valves

Do not grind the valves themselves, no grinding is allowed.

1. Place the seals (13) on the exhaust valve guides.
2. Lubricate with oil and install valves.
3. Install spring support washers (23).
4. Install springs (21, 22) with plates (24).
5. Fit the studs (25) using tool 9838 (see Fig. 14).

Setting jets:

Installation of YaMZ-650 injectors

1. Install injector (2) with copper washer (1) (312383) into injector hole in cylinder head. (When installing it, the fuel supply hole must be directed towards the intake ports of the cylinder head).
2. Install the fuel supply fitting to the injector (6). (Respect orientation (B)).
3. Maneuver the injector (2) and the nozzle for supplying fuel to the injector (6) so that the cones of the nozzle and the holes in the injector meet.
4. Screw on the union nut (7).
5. Fit the injector bracket (3).
6. Replace the spherical washer (4) (312391).
7. Tighten the injector bracket bolt (5).
8. Pre-tighten the bolt of the injector bracket (5) and the union nut (7) to a torque of no more than 5 Nm.
Finally tighten the injector bracket bolt (5) and the nozzle attachment nut (7) to 60 Nm.
9. Check the protrusion of the injectors.

Installing the coolant drain box from the cylinder head:

Installing the coolant drain box gasket from the YaMZ-650 cylinder head

1. Install the seal (2) in the coolant drain box from the cylinder head (1) (see Fig. 16).
2. Install the coolant drain box from the cylinder head.
3. Screw on the coolant drain box bolts from the cylinder head and finally tighten Mcr = 20 ± 4 Nm, following the specified tightening order (see Fig. 17)