In detail: do-it-yourself repair of a KamAZ head from a real master for the site my.housecope.com.
TECHNOLOGICAL CARD № 1.4.
REPAIR OF THE CYLINDER HEAD OF THE KAMAZ-740 ENGINE
Total labor intensity - 57.0 people. min
DISASSEMBLY OF THE CYLINDER HEAD OF THE KAMAZ-740 ENGINE
Labor intensity - 17.0 people. min
1. Install the cylinder head assembly onto the disassembly tool. (Workbench for locksmiths, device for disassembling and assembling the head).
2. Unbend the antennae of the lock washer securing the rocker arm strut. (Hammer, chisel).
3. Unscrew the nuts 18 (Fig. 1) fastening the rocker arm axle struts. (Replaceable head 17 mm, wrench with p. K.).
4. Remove the rocker arm post, lock washers and rocker retainer.
5. Remove the rocker arms 8 (Fig. 2) of the valves from the rocker arm post.
6. Unscrew and remove the nut 7 from the adjusting screw and unscrew the adjusting screw 5 of the rocker arm. (Wrench 17 mm, screwdriver 10.0 mm).
7. Remove the cylinder head from the disassembly tool. (Workbench for locksmiths, device for disassembling and assembling the head).
8. Install the cylinder head on the valve remover).
9. Rotate the handle 2 to squeeze the spring plate 12 (Fig. 1) together with the bushing 11, and remove the 10 valve crackers, 11 valve spring plates, valve spring plates 12, outer 13 and inner 14 springs and 16 valve spring washers. (Screwdriver 10.0 mm).
10. Remove the sealing collar 15 (Fig. 4) of the inlet valve assembly with the collar ring 16 from the guide sleeve 18 of the inlet valve. (Screwdriver 10.0 mm).
11. Remove the inlet 20 and outlet 1 valves.
12. Unscrew the screw 29 fastening the intake manifold and the screw 30 fastening the water pipe.
Video (click to play).
Perform work if necessary to replace the screwdriver. (Key for turning the screw-in
return the studs 21 for attaching the exhaust manifold pipe, studs 26 for attaching the rocker arm struts and pins 24 for attaching the injector bracket. Perform the work if necessary to replace the studs. (Tool for unscrewing the studs).
14. Remove cylinder head 31 from the tool. (Valve remover).
WASHING THE CYLINDER HEAD PARTS
15. Rinse the removed parts and the cylinder head, clean the valve, valve seats, valve guides, the block head and blow them off with compressed air. (Installation for washing parts, model 196 M or "Typhoon", metal brush; metal brushes, emery paper No. 280-320, a gun for blowing parts with compressed air mrd S-417).
DEFECTIVE CYLINDER HEAD PARTS
16. Defect parts of the cylinder head. Troubleshooting should be performed according to the troubleshooting card No. 1.3.
17. Install the cylinder head on a stand for crimping the head, check the head tightness and, if necessary, eliminate the leakage. Check at a pressure of 0.4 MPa (4 kgf / cmg) for 2 minutes. Fluid leaks and leaks are not allowed. (Stand for crimping, stopwatch).
If you love your KamAZ and undertook to provide it with emergency technical assistance with your own hands, do not forget that when servicing trucks you need to follow certain rules and sequence of actions, especially when it comes to its engine or removable engine elements.
Lapping engine valves
To ensure that the valves are lapped in, the valve train must be disassembled. Now you need to carry out the procedure for preparing a special paste. It will consist of three components in a certain ratio. Half of the paste will be green silicon carbide micropowder, 1/3 of the volume will be diesel oil and 1/6 will be diesel fuel.Immediately before use, the already prepared lapping paste must be thoroughly mixed in order to stir up the micropowder, which tends to precipitate.
Now apply a thin layer of paste to the chamfer of the valve seat carefully and evenly. Do not forget to clean the valve stem with a cloth that has been previously soaked in engine oil. Lapping is carried out by the reciprocating movement of the valve using a drill fitted with a suction cup or similar. When the valve is pressed, it turns in a circular motion, first by 1/3 of a turn, and then by ¼ of a turn, only in the opposite direction. The grinding process does not stop until a uniform matte belt appears on the chamfers of the valve and seat, the width of which is at least 1.5 mm.
Checking the quality of valve lapping
At the end of the lapping procedure, the valves and cylinder head are flushed with diesel fuel and blown with air. The valve train can now be reassembled. In doing so, the quality of the valve lapping should be determined using a standard tightness test.
Such a check begins with the fact that the cylinder head is installed in turn, the intake and exhaust ports are upwards, and diesel fuel is poured into them. If the valves are lapped well, then they do not allow fuel to pass through the seals for 30 seconds. If the fuel still leaks, take a rubber mallet and tap it on the end of the valve. If this does not help and the leakage continues, the valves are lapped again.
Also, the quality of lapping can be checked by applying marks (5 pieces, maximum 8) with a soft graphite pencil perpendicular to the chamfer of the valve at approximately the same distance from each other. The valve is now gently pushed into the seat with a push and a ¼ turn. It is necessary that all marks are erased, if this does not happen, grinding the valves also requires a second procedure.
In case of an immediate need to repair the engine, you can do it yourself, guided by some manuals or instructions.
Repair work with a KamAZ engine consists of many procedures and tricks that will help prolong the life of your car. Below are presented.
When the engine fails, you can do a lot of work to fix its malfunctions. The main thing is to first figure out what is the reason for these.
Timely identification of truck engine malfunctions, as well as knowledge of the causes of specific signs of damage to parts, helps.
In case of a certain malfunction in the KamAZ engine, it is possible to independently provide the unit with all the necessary maintenance,.
Each head of the Kamaz-740 block is installed on two locating pins, pressed into the cylinder block, and fastened with four alloy steel bolts.
One of the locating pins simultaneously serves as a bushing for supplying oil to lubricate the rocker arms. The sleeve is sealed with rubber rings.
In the Kamaz-740 cylinder head, in comparison with the 740.10 engine head, the engine oil drain hole from under the valve cover into the rod cavity is increased. The intake and exhaust ports are located on opposite sides of the cylinder head.
The inlet channel has a tangential profile to ensure optimal rotational movement of the air charge, which determines the parameters of the working process and the environmental performance of the engine, therefore, replacement with the cylinder heads of the 740.10 engine is not allowed.
Cast iron seats and sintered valve guides are pressed into the cylinder head of the Kamaz-740. The valve seats have an increased interference fit compared to the 740.10 engine seats, and are fixed with a sharp edge.
The outlet seat and valve are profiled to provide less resistance to exhaust gas discharge.The use of outlet valve 740.10 is not recommended.
The joint "cylinder head - sleeve" Kamaz-740 (gas joint) is unlined. A steel O-ring is pressed into the bore groove on the lower plane of the head.
Through this ring, the Kamaz-740 cylinder head is installed on the liner collar. The tightness of the seal is ensured by high precision machining of the mating surfaces of the O-ring and the cylinder liner.
The O-ring has an additional lead coating to compensate for the roughness of the sealing surfaces.
The cylinder heads contain the valve mechanism and the injector. The valve mechanism of the head is closed by an aluminum cover, sealed with a gasket. Cast iron seats and sintered valve guides are bored after being pressed into the head.
Each head is secured to the cylinder block with four bolts. To avoid breaking the tightness of the gas joint, the bolts are tightened in a cross pattern in three steps.
The inlet and outlet ports are located on opposite sides of the head. When looking at the engine from the side, the intake valves of the heads are on the right, and the exhaust valves are on the left.
The inlet channel has a tangential profile, providing a vortex movement of air in the cylinder, improving mixture formation and accelerating the combustion process of the injected fuel. The injector socket is located on the side of the exhaust valve at an angle to the cylinder axis.
It is necessary to remove the cylinder head quite often. At least every 40-50 thousand kilometers. This is how the KamAZ engine is structurally arranged. Leaking coolant or oil is the cause. Dismantling the cylinder head will also be required to repair the piston group or the gas distribution mechanism.
Let's take a step-by-step and detailed look at the process of dismantling the head of the KamAZ 740 engine block.
1. Drain at least half of the coolant from the cooling system.
2. To dismantle the heads of the block of some cylinders, it will be necessary to dismantle the coolant expansion tank and the compressor.
3. Remove the intake and exhaust manifolds, and also unscrew all interfering fuel pipes.
4. Unscrew the bolt securing the block head cover with a 13 key.
5. Remove the cover and gasket.
6. If you need to remove only one head, you will have to remove the cover from the adjacent head of the block so that its protrusion does not interfere with dismantling.
7. To dismantle the cylinder head of the fourth and eighth cylinders, you will need to unscrew the nuts securing the cab springs with a 17 key and move them aside along with the shock absorbers.
8. It is advisable to fix the rods of the gas distribution mechanism, for example, by tying them together in order to avoid them falling into the pallet when removing the cylinder head.
9. Unscrew the four bolts securing the head to the block using a 19 socket or box wrench.
10. Remove the head of the block by prying it with a mounting spade and at the same time swinging it by inserting it into the hole of the screw securing the wrench.
11. The head should be cleaned of dirt and carbon deposits. After that, replace the three O-rings ("barrels") of the water holes.
O-rings are included in the repair kit for rubber goods of the head of the KamAZ 740 engine block. In the vocabulary of auto repairmen, their name is found - a barrel.
12. Place a new O-ring on the oil channel bushing.
thirteen.We install a new cylinder head gasket on the engine block and put the rods in place.
14. Reinstall the block head. The cylinder head mounting bolts should be tightened crosswise in three steps.
The final tightening torque of the bolts of the KamAZ 740 engine block head is 16-18 kgf * m.
The kit consists of: 1.740.1003 040 Oil channel sealing ring - 16 pcs. 2. 740.1003 214-04 Sealing ring (cylinder head) "barrel", installed in the holes of the coolant channels - 24 pcs. 3.740.1003 213-26 Cylinder head gasket - 8 pcs.
4.740.1003270 Cylinder head sealing cover gasket - 8 pcs.
Cylinder head gaskets can be old or new.
Taking into account the interchangeability of the heads of the KamAZ 740 engine block, it is preferable for repairs to replace the cylinder head with a new one.
If necessary, repairs are often carried out:
Replacing valve seats.
Seat machining - valve lapping.
Saddle socket boring.
Plane restoration
The engine of KamAZ 740 cars is designed in such a way that each cylinder of the block has its own head. Accordingly, under each Cylinder head KamAZ there is a separate gasket that ensures its tight fit to the block, or rather the tightness of the water and oil channels.
However, in consequence, temperature exposure, incorrect installation, Bad quality and a number of other destructive factors, breakdown (burnout) of such gaskets quite often happens. Therefore, replacing the gasket under one or more heads is quite a common procedure.
leakage of oil or coolant from under the head to the outside... The most common option for KamAZ vehicles. It is detected by the presence of streaks on the block. Often, due to the exhaust manifold, it is difficult to determine unambiguously which of the heads "leaked". After dismantling it, it becomes clear which of the heads needs to be removed.
exit from under the head of the exhaust gases, which is manifested by a rather loud soundtrack when the engine is running. Quite a rare occurrence for a KamAZ engine. Considering that the function of sealing the head and cylinder (combustion chamber) is taken over by the steel ring of the gas joint, the gasket will burn out as a result of damage to this part. If the ring seat has not been deformed, it will need to be replaced. Otherwise, it may be necessary to replace the head with a new one.
after dismantling the cylinder head for any of the above reasons, and for cylinder head repair, gas distribution and crank mechanism, replacement of the worn-out head bolt to the block, etc.
In addition to the rubber gasket, for each head it will be necessary to replace 2 O-rings on the bushings of the oil channels, as well as 3 seals for the water holes, which have the shape of a "barrel", for which they are nicknamed in the jargon of auto technicians. The gas joint can be provided with a fluoroplastic gasket.
Also, it may be necessary to replace the valve cover gasket and gaskets under the intake and exhaust manifolds.
Before starting work, you will need to drain at least half of the total volume of the coolant. And also, dismantle the interfering expansion tank and compressor.
Using a 19 wrench, unscrew the union nuts of the high pressure pipe from the injection pump section
Also, it is necessary to unscrew the fuel pipe from the injector of the head to be dismantled.
Using a spanner or socket wrench 14, unscrew the union of the drain tube of the injectors and remove it.
Remove the water pipe using a 13 socket wrench and the intake manifold with a 17 socket wrench.
Using a 13 key, unscrew the bolt securing the valve cover of the block head. And remove the cover along with the gasket. You will also have to remove the adjacent cover, the protrusion of which will interfere with the dismantling of the cylinder head of the block.
Using a 19 socket or box wrench, unscrew the 4 bolts securing the cylinder head of the block.Move the intake manifold and water pipe back from the head with the inserted knob. Having inserted the knob into the hole of the head for the bolt, swing it and remove it by prying the head with a mounting blade over the edge of the outlet pipe.
The removed head must be thoroughly cleaned of carbon deposits and troubleshooting must be performed. If the head is not damaged, replace the O-rings of the water passages with new ones. And also the sealing rubber ring of the bushing of the oil channel.
Install a new cylinder head gasket on the block.
The tightening torque must be:
the first reception - 39 ... 49 N m (4 ... .5 kgf m);
the second reception - 98 ... 127 N m (10 ... 13 kgf m);
the third reception - 186 ... 206 N m (19 ... 21 kgf m) the limiting value.
After tightening the bolts, it is necessary to adjust the clearances between the valves and the rocker arms. The clearance is necessary to ensure a tight fit of the valve to the seat during thermal expansion of parts during engine operation.
