The cylinder head in the engine is a rather specific unit. Failures of this mechanism can lead to complete inoperability of the vehicle. For example, malfunctions of the surface of the cylinder head and the cylinder block can be caused by breakdown of the gasket. This entails other troubles. 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, the engine will die completely. Therefore, the problem must be urgently addressed. An operation such as milling cylinder head will help restore the plane of the head.
Cylinder head characteristic
The cylinder head, as already noted above, is one of the most important components of any internal combustion engines. All the main parts of the gas distribution mechanism of the engine are installed in the head.
This is a complex element, and most often it is made of aluminum alloys or of alloyed cast iron. So that the cylinder head and engine block can reliably interact with each other, the cylinder head is expanded from below and its mating plane is perfectly flat.
Design features
The design has 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-shaped engines have a separate head for each row of cylinders.
Holes on the cylinder head are necessary for the installation of nozzles, spark plugs. Valve springs, valve bushings, thrust washers, camshaft bearing housings are installed in the upper niche. Also in the housing there are holes for installing the intake and exhaust manifold.
When is cylinder head milling needed?
So, the purpose of milling is the process of fine-tuning the surface of the head interacting with the cylinder block to the necessary criteria for mating planes.
This operation is performed in two cases. Usually the head is milled when tuning the engine is done. So, the cylinder head height is often reduced to increase the compression ratio of the motor. This is not relevant for ordinary car enthusiasts, because ordinary drivers have enough staffing characteristics and capabilities of the internal combustion engine.
In case of repair, cylinder head cannot be dispensed with. It is a must. Any engine overhaul 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 the banal burnt-in gasket to the block head is already a reason for processing.
Is it possible to mill with your own hands?
It must be understood that milling of the cylinder head is impossible without special equipment, or rather, without a milling machine. If there is 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 “live”. Manually, you can only polish the surface if the gasket burns.
When the head is dismantled from the motor and mounted on the machine, the milling thickness is the first thing that matters. In this case, you need to find out the maximum repair depth of milling. This is indicated in the service documentation for the vehicle. If this parameter is observed, then no problems with the engine will arise.
Do not try to do the work yourself. Modern cylinder head milling machines are equipped with a software system that has high precision. It is not possible to “remove” a layer of metal of strictly necessary thickness by eye. It is much better for nerves and the budget to use the services of professionals.
How to clean the surface from the old gasket?
This must be done before grinding milling the cylinder head. You will need an ordinary knife or a grindstone from grinding machines. Working with a stone, make circular movements or movements in the form of a figure eight. They must be as smooth as possible.
After removing the rest of the gasket, you will see how the cylinder head is deformed. This treatment should be carried out until all the irregularities are aligned. As a result, you need to get the most even and preferably a mirror plane. This ensures a good seal.
How to prepare the cylinder head?
It should be remembered that before performing work, you need to check the plane. You can do it yourself. 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 the probe is selected, which will pass between the ruler and the attachment plane. This measurement method will not give much accuracy, but you can roughly understand how the node is deformed. Typically, the plane is strongly deformed in the area of the pistons, where there is soot, or at the place of penetration of the gasket.
It should also be borne in mind that the milling of the VAZ cylinder head should only be performed after a complete check of the assembly for microcracks and other defects. Before this operation, all defects must be excluded. In order to find cracks, you will need a special fluid - it will immediately show the defective places.
After applying the liquid to the surface, wait five or more minutes before rinsing it off. If the surface of the cylinder head has defects, then the coloring pigment will clog exactly in the cracks. But only external flaws can be detected in this way.
Milling cutters
The machine is not as important as the set of milling cutters for milling cylinder head. End mills with five-sided inserts are the most common. They were produced in the USSR in accordance with GOST 26595-85. These are powerful cutting tools for roughing and semi-finishing of steel and cast iron. But this mill is not suitable for work with pure aluminum. However, surface quality can be improved if necessary. Replaceable plates on such mills do not have grooves for chip flow. The plate receives shock loads, but there is no surface quality. But these 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 very small - on sale you can find T5K10 and T15K6.
To do the milling of the cylinder head with the available tools to achieve better results, 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 speed should be large.
Conclusion
Not having the proper experience of working on milling machines, you should not try to engage in the milling of 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.