Heavy maintenance, a lot of people with his own experience, tend to ignore some of the details, but these seemingly insignificant details sometimes cause damage to vehicles, small make up take stock to everyone today heavy card maintenance nine big fear.
Oil is only added to oil without engine oil
The engine oil is essential in the use of diesel engine, which mainly lubricates, cools and cleans.Many drivers will pay attention to check the oil amount of oil and add to the standard, but ignore the inspection of the oil quality and the replacement of the oil, causing some engine parts to wear out.In normal circumstances, the loss of oil is not large, but it is very easy to pollute, thus losing the protection of diesel engine.In the process of diesel engine operation, many dirt will enter into the oil, for new or after major repair machinery, commissioning after impurities will be more, if only add not in rush to put into use, it is easy to cause tile burning, holding shaft and other accidents.In addition, even if the oil change, some drivers due to lack of maintenance experience or graph save trouble, also when replacement is not thoroughly clean the oil duct, make the mechanical impurity still lingers in the oil pan and oil.
3.Avoid cylinder liner and piston products are not selected and installed
In the change of cylinder liner and piston, it is considered that the new cylinder sleeve and the piston are all standard parts. They are interchangeable and can be used.In fact, cylinder jacket and piston dimensions have certain tolerance range.If the maximum size cylinder sleeve is fitted with the minimum size piston, it will make the gap too large, resulting in compression and failure.Change, therefore, must want to check the size of the standard cylinder liner and piston group code, equipped with standard of cylinder liner and piston must make the size of the piston group code and the size of the standard cylinder liner group code is the same, only in this way can ensure a standard fit clearance between.In addition, the cylinder sleeve with the same grouping code for each cylinder and the piston of the same time, should also pay attention to the inspection of the piston clearance, to ensure the assembly standard, should also carry out a test before the installation.
4.Avoid cylinder clearance measurement
When measuring cylinder clearance, the piston skirt is not measured in the direction perpendicular to the piston pin hole, but in other direction.The structural features of the aluminum alloy piston are small and large, and a cone, and the local section is elliptic, so the air cylinder clearance along the circumference of the cylinder is not equal.When measuring, the regulation is based on the gap between the axial direction of the ellipse, which is to measure the clearance of the piston skirt in the direction of the piston pin.Such measurement is more convenient, accurate, and in reciprocating motion, the piston skirt is perpendicular to the direction of the piston pin hole just wear away from the effect of lateral pressure is bigger, so the measuring cylinder clearance, should be vertical to the piston pin hole in piston skirt in the direction of the measurement.
5.Avoid piston flame heating
Because the piston and piston pin is interference fit, so when installing a piston pin, should first make the piston thermal expansion, at this time, some of the maintenance personnel will put the piston on the flame heating directly, so it is very wrong, because each part of the piston, uneven heat bilges cold shrink degree would be different, firing can make the piston balance, easy to cause deformation;The piston surface also attaches to the coal ash, reducing the life of the piston.If the piston reaches a certain temperature and then naturally cools, its metallographic tissue will be damaged and the wear-resisting performance will be greatly reduced and its service life will be significantly shortened.When installing the piston pin, the piston can be heated evenly in hot oil to make it expand slowly.
6.Avoid grinding the bush with emery cloth
For some inexperienced mechanic, bush is a difficult work, because the scraping tile technology hard to master, so the bearing shell is not easy to meet the technical requirements, therefore, when someone replacing bearing shell, to increase the contact area of bearing shell and crankshaft, with emery cloth grinding instead of blow.This method is highly desirable in the actual repair, because of the abrasive cloth is hard, and the bearing alloy is soft, so when grinding sand easily embedded in the alloy, the diesel engine work will accelerate journal wear, shorten the service life of the crankshaft.
7.Don't bolt the bolt too tight
Disassembling process, many parts of the bolt are torque requirements, such as transmission box, cylinder cover, tires, connecting rod, and, in areas such as the front axle tightening torque has special provisions in the specification, must not optional change.But many use people to think that tighter is safer, but tightening too tight can cause bolts or bolts to break, or it can be caused by thread slips.
8.Avoid tyre pressure too high
Tire pressure of wheel type engineering machinery is an important factor to determine its service life and working efficiency.Too high or too low tire pressure can affect their service life, and it is also bad for safe driving, especially in hot summer.The standard of scientific inflation should be: based on the standard air pressure of the tire, with the change of temperature, the tire pressure will adjust slightly.
9.Do not use the water tank to add cold water
The engine overloads, the heat dissipation, or the water shortage of the water tank will cause the water tank to open the pan. If you add cold water immediately, it will cause the cylinder head and cylinder to burst.Therefore, once the water tank is found in the water tank, emergency measures should be taken to stop the operation, so that the coolant of the diesel engine cools itself.