The cylinder head in the engine is a rather specific unit. Malfunctions of this mechanism can lead to complete inoperability of the vehicle. For example, violations of the mating surface of the cylinder head and cylinder block can be caused by a breakdown of the gasket. This leads to other troubles as well. So, antifreeze gets into the oil. There will also be oil in the expansion tank and in the cooling system. If you operate a car with such a malfunction, then the engine will die completely. Therefore, the problem needs to be fixed urgently. An operation such as cylinder head milling will help restore the plane of the head.
Cylinder head characteristics
The cylinder head, as noted above, is one of the most important components of any internal combustion engine. All the main parts of the gas distribution mechanism of the internal combustion engine are installed in the head.
This is a complex element, and is most often madeit is made of aluminum alloys or alloyed cast iron. So that the cylinder head and the engine block can reliably interact with each other, the bottom of the cylinder head is expanded, and its mating plane is perfectly flat.
Design Features
The design contains a variety of elements - these are spark plugs, nozzles, glow plugs, camshafts. Valves are also integrated into the head - inlet and inlet. In-line engines are equipped with one cylinder head, and V-engines have a separate head for each row of cylinders.
Holes on the cylinder head are required for mounting injectors, spark plugs. Valve springs, valve bushings, support washers, camshaft bearing housings are installed in the upper niche. Also in the housing there are holes for installing the intake and exhaust manifolds.
When is cylinder head milling needed?
So, the purpose of milling is the process of finishing the surface of the head, which interacts with the cylinder block, to the required criteria for mating planes.
This operation is performed in two cases. Usually the head is milled when tuning the engine. So, they often reduce the height of the cylinder head in order to increase the compression ratio of the engine. This is not relevant for ordinary motorists, because ordinary drivers have enough regular characteristics and capabilities of the internal combustion engine.
In case of repair, cylinder head milling is indispensable. It is mandatory. Any overhaul of the engine is not carried out without this procedure. One way or another, but any engine at least once, but was subjected to overheating. And overheating adversely affects the mating plane. Often the result of overheating is the deformation of the block head. As for the repair, it can be any operation. For example, from replacing gaskets to repairing or replacing camshafts. Even a banal burnt gasket to the block head is already a reason for processing.
Is it possible to mill with your own hands?
You need to understand that cylinder head milling is impossible without special equipment, or rather, without a milling machine. With such a machine in the garage, the operation is feasible. As for the machine itself, the main thing is that it should be at least a little “alive”. Manually, you can only grind the surface if the gasket is burnt.
When the head is dismantled from the motor and installed on the machine, the first thing that matters is the thickness of the milling. In this case, you need to find out the maximum repair depth of milling. This is indicated in the service documentation for the car. If this parameter is observed, then there will be no problems with the engine.
Don't try to do the work yourself. Modern cylinder head milling machines are equipped with a software system that has high accuracy. By eye, it will not be possible to “remove” a layer of metal of a strictly required thickness. It is much better for nerves and budget to use the services of professionals.
How to clean the surface of the old gasket?
This must be done before grinding and milling the cylinder head. You will need an ordinary knife or a grindstone from grinding machines. Working with a stone, they make circular movements or movements in the form of a figure eight. They must be as smooth as possible.
After removing the remnants of the gasket, you will see how the cylinder head is deformed. Such processing should be carried out until all irregularities are leveled. As a result, you need to get the most even and preferably a mirror plane. This ensures a good seal.
How to properly prepare the cylinder head?
It should be remembered that before performing work, you need to check the plane. This can be done by hand. To do this, you need a set of probes and an ordinary ruler. The latter is placed in turn on each diagonal of the lower plane of the cylinder head and then a probe is selected that will pass between the ruler and the mating plane. This measurement method will not give much accuracy, but you can roughly understand how the node is deformed. Usually the plane is strongly deformed in the area of the pistons, where there is carbon deposits, or in the place where the gasket is broken.
It should also be borne in mind that the milling of the VAZ cylinder head should be performed only after a complete check of the assembly for microcracks and other defects. Before this operation, all defects must be eliminated. In order to find cracks, you need a special liquid - it will immediately show defective areas.
After applying the liquid to the surface, wait five minutes or more before washing it off. If the surface of the cylinder head has defects, then the coloring pigment will clog precisely into the cracks. But this can only reveal external flaws.
Cutters
The machine is not as important as a set of cutters for milling a cylinder head. The most common end mills with pentagonal inserts. They were produced in the USSR according to GOST 26595-85. These are powerful cutting tools for roughing and semi-finishing of steel and cast iron. But this cutter is not very suitable for working with pure aluminum. However, if necessary, the surface quality can be improved. Indexable inserts on these cutters do not have a chip flow groove. The plate receives shock loads, but there is no surface quality. But the same plates, equipped with such a groove, make it possible to obtain a surface many times better. As for the choice of alloys, it is quite small - you can find T5K10 and T15K6 on sale.
In order to achieve better results by do-it-yourself cylinder head milling with the available tools, 6 wedges are removed from the cutter and only two plates are left. When working on the machine, the feed should be low, and the revolutions should be high.
Conclusion
Without the proper experience of working on milling machines, you should not try to mill such a critical part as the cylinder head. It is best to trust professionals, but you need to choose wisely. Now services are provided by different masters, and not all are equally qualified and experienced.
