Replacing the cylinder head gaskets of the 740 Kamaz diesel engine

We replace the cylinder head gaskets when leaks of coolant and oil appear at the joint between the cylinder head and the cylinder block.

To carry out the work we shall need the following tools: spanners 8×10, 12×13, 17×19, 22×24, 27×30, interchangeable sockets 13, 14, 17, 19 mm, socket handle, pry bar, screwdriver, chisel, hammer, flat scraper, jack, stand, containers for fuel, oil and coolant, torque wrench.

1. First of all we disconnect the electrical leads from the batteries.
2. We drain the coolant.
3. We unscrew the bolts and remove the cover of the front hatch of the clutch housing.
4. We raise the front of the vehicle and place a stand under the first frame cross-member.

5. With a 14 mm socket and a spanner we unscrew the drain line (return), Figure 2.

6. We unscrew the high-pressure pipes from the engine injectors.

7. We unscrew the high-pressure pipes from the high-pressure fuel pump, Figure 4.

8. We slacken the exhaust manifold retaining bolts (Fig. 5).
9. We remove the intake manifolds.
10. With a 13 mm socket we unscrew the bolts and detach the thermostat housing flange.
11. We unscrew the water pipe retaining bolts and, with a pry bar, separate the pipes from the cylinder heads.

12. We unscrew the bolts 1 (Fig. 5) retaining the cylinder head covers and remove the covers 2 with the gaskets 3.
13. On the heads of the fourth and eighth cylinders the rocker pillar retaining nuts must be unscrewed and the pillars removed complete with rockers and rocker retainers and pushrod tubes.

14. With a 19 mm socket we slacken the cylinder head retaining bolts in the sequence shown in Figure 6, then unscrew them, remove the heads and mark their numbers.

Important! The head must not be placed on its mating face, so as not to damage the injector nozzles.

15. We withdraw the pushrods and lay them out according to the numbers of the cylinder heads.
16. We remove the cylinder head gaskets: the sealing gasket and the steel gasket for the gas joint.
17. We clean the mating surfaces of the cylinder heads and the cylinder block of carbon deposits and scale.

Fitting the cylinder head gaskets

1. We fit the sealing gaskets onto the cylinder block.
2. We fit new steel cylinder head gaskets onto the upper end face of the liners (before fitting we lubricate the steel gaskets with engine oil).
3. We fit the pushrods and screw in the adjusting screws.
4. We blow out the threaded holes, clean them of dirt and blow them with compressed air.
5. We fit the cylinder heads, centring them on the block dowels. At the same time we must make sure that the thermal clearance adjusting screws enter the ends of the pushrods.
6. Before screwing in the head bolts we lubricate the threaded part of the bolts with graphite grease mixed with engine oil.
7. We tighten the head retaining bolts in three stages in the sequence shown in Figure 6:
   • first stage — 39.2÷49.1 N·m (4–5 kgf·m);
   • second stage — 117.7÷147.2 N·m (12–15 kgf·m);
   • third stage — 156.9÷176.5 N·m (16–18 kgf·m).
8. We adjust the thermal clearances in the valve gear. Clearance for the inlet valves: 0.25–0.30 mm; for the exhaust valves: 0.35–0.40 mm.
9. We fit the front clutch housing cover.
10. We screw in the exhaust manifold retaining bolts.
11. We fit the head covers with gaskets and secure them with bolts with flat washers.
12. We fit the water pipe gaskets, the water pipes complete with the connecting pipe, and tighten them with bolts with flat and spring washers.
13. We attach the thermostat housing flange with bolts with flat and spring washers.
14. We fit the intake manifolds and connect the pipes to the heads.
15. We remove the stand from under the front of the vehicle and fill the coolant.
16. We connect the electrical leads to the battery.
17. We start the engine and check the operation of the valve gear.