1. Introduction
In the above cylinder head is mounted, and the upper seal cylinder defining the combustion chamber. It is often in contact with high pressure gas, thus subjected to high thermal and mechanical loads. The cylinder head is made of water-cooled engine with a cooling water jacket, cooling water hole and a cooling water hole of a cylinder head in communication with the end face. Use of recycled water to cool the high temperature portion of the combustion chamber and the like.
further provided with a cylinder head intake and exhaust valve seat, valve guide holes for mounting intake and exhaust valves, and intake and exhaust passages and the like. Gasoline engine cylinder head machined with the spark plug mounting hole, and machining the cylinder head of the diesel engine injector mounting hole. The overhead camshaft engine cylinder head is also machined with camshaft bearing bore for mounting the camshaft.
The cylinder head is generally gray cast iron or alloy cast using cast, good thermal conductivity of aluminum, help to improve the compression ratio.
The cylinder head is an integral part of the combustion chamber, combustion chamber shape greatly influence the work of the engine, due to the different combustion gasoline and diesel engines, the cylinder head portion of a larger difference in composition of the combustion chamber. Gasoline main combustion chamber in the cylinder head, a combustion chamber of the diesel engine and the main pits top of the piston. 
2, cylinder head cracks measures
1, the head bolt to be tightened evenly and properly adjust the injection timing.
2, the tank should be added to soft water, changing the water and less as possible.
3, Diesel should be avoided in the long-term overload.
4, when the engine is operating and the water tank occasionally may not turn off immediately, but should be low speed slowly add water. Add cold water after the engine may not take the heat, the water temperature should stop to below 40 ℃ and then turn on the water. Winter season not immediately start adding water, while heated water should add water.
5, the assembly should be checked whether each coolant flow hole. Cooling regular cleaning with an alkaline solution, the timely removal of scale oil. 
3, knock Cause Cause
causing knocking are:
1. Oil too early
When Sleeve diesel generator set upward movement of the piston has not reached a predetermined position of the injector, the injector starts injection, combustion of fuel in advance, the impact of high pressure gas within the cylinder piston, given the rhythmic “despair, despair” knocking sound crisp, reduce the throttle, knocking sound obvious.
The method is excluded: fuel supply advance angle adjustment, i.e., increasing the spacers between the fuel pump so that the gearbox oil to meet the required time delay injection time. Each additional spacer 0.1 mm, 1.3-1.7 supply advance angle may be delayed.
2. Fuel combustion failure
The injection pressure is too low, the injector drip, poor atomization and fuel injection and other oil too late will result in poor fuel combustion caused by knock. Knocking sound caused by such failures low, husky voice accompanied by engine overheating, black smoke or exhaust pipes blasting, flame and so on. Remove the injectors should be checked and adjusted, adjust injection timing, replaced with new parts, if necessary, to conform to the regulations.
3. Oil valve wear 
4, and fault handling pull cylinder
1 Scuffing phenomena:
The mechanism of scuffing damage due to the sliding most lubricant film subjected to localized damage site, and the two projecting portions of the first metal surfaces in relative motion into contact, then occurs locally slight quot; blow quot; phenomenon, the blow portion relative motion member has been torn. to the metal surface of the hardened layer in the process, when the hardened layer is damaged, the metal grains produced will be increased wear of the surfaces in the material Mo so-called quot;. wear blow quot; short period of time, and the piston and appear on the center of the cylinder surface of the cylinderLine parallel rugged wear scar, which is the phenomenon of scuffing. Severe sticking or jamming the sliding portions may even completely cracked at both surfaces of the weak parts causes mechanical damage, i.e., seizures. Therefore, the scuffing The fundamental reason is seizing wear.
2 Scuffing of reasons:
cause of scuffing is very complex, the design of reasons, such as the installation of an optional material, determining the size of the gap, means for moderate is appropriate, the structural arrangement is reasonable, whether the appropriate surface roughness, whether perfect lubrication and cooling arrangements, etc., from a management perspective, it may be due to the following reasons:
(1) cylinder with a poor lubrication:
cylinder oil the reason insufficient supply or interruption occurs in direct contact with a metal cylinder with a poor lubrication of the cylinder is pulled are: oil sump poor quality of the oil or too little, or too high temperature of the diesel engine piston ring (mainly oil ring) or damage such as the failure.
(2) insufficient running:
effectively running in the shortest possible time, running time and must be considered in the load distribution problem even after long running low load running not completed, and if. after the renewal of the piston and the cylinder liner; break-in period should be appropriate to increase the fuel injection; should be a period of operation at low load a new one after the piston ring: rush high load operation, will cause scuffing Thus, the diesel engine should be noted that in the run-in period. It should be running and then increase the load operation.
(3) poor cooling:
will cause poor cooling cylinder, the piston temperature is too high, poor lubrication; poor cooling piston and the cylinder sleeve causes overheating and over-expansion deformation, lose their normal gap pull-cooled cylinder. the reason there are poor: the cooling water pump discharge pressure is insufficient, inadequate or interrupted water supply; cooling water chamber rust or dirt; water containing air bubbles accumulated in the cooling chamber did not release caused by air resistance; dirty water, the water temperature is too high.
(4) the piston ring does not work properly:
the opening gap is too small, so that the piston ring fault; World gap is too small, so that stuck piston rings; too much carbon, piston ring sticking lose ring groove elasticity, causing gas leak or fracture; open gap is too large or badly worn, leakage of gas leak occurs destroyed lubricating film, so that the surface temperature is too high after the piston to cause the broken pieces fall easily to pull the cylinder between the piston cylinder. seizures.
(5) using poor quality fuel:
Incomplete combustion bring more combustion residues; serious post-combustion, the exhaust gas temperature rises, technical measures are not taken in a timely manner; unsuitable cylinder lubricating base value. Moreover, some diesel engines because of long-term overload, the thermal load increases, the expansion or overheating failure in the moving parts of the cylinder is pulled.
(6) assembly errors Repair:
repair leakage loaded piston pin retaining ring assembly errors or not fully charged, the diesel engine during operation of the piston causes pin sprang scratch liner pull-cylinder difference cleaning installation. , the metal shavings or crushed hard objects into the tank can cause scuffing. Further piston placed incorrectly installed anti scuffing can cause leakage loaded piston rings have oil ring and gas ring, the oil ring main for scraping the oil, improving lubrication liner. guarantee seal gas ring main piston and cylinder in accordance with different operating conditions and under pressure of each gas ring vary in structural design and material selection, such as the piston ring placed incorrectly installed backwards or drain means can cause poor sealing or no oil scraping effect, so that the inner liner surface lubrication caused by lack of oil deterioration caused by scuffing.