1, oil and not only in the using of diesel engine oil change is necessary, mainly plays a role of lubrication, cooling and cleaning, etc.
As a result, many drivers will pay attention to the oil amount to check the oil, and according to the standard to add, but neglected the lubricating oil quality check and has deteriorated oil replacement, cause some engine moving parts are always in poor lubrication conditions, so as to accelerate the wear parts.
Under normal circumstances the oil consumption is not large, but it is very easy to pollution, to protect the role of the diesel engine.
In the process of diesel engine operation, many dirt (
Fuel oil incomplete combustion generated carbon smoke, carbon deposit and scale, etc. )
Will enter into the oil.
For new or after major repair machinery, commissioning after impurities will be more, if only not change is eager to be 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.
2, the indiscriminate use of butter coated cylinder MATS and butter.
Butter is commonly used in engineering machinery repair grease, can play the role of lubrication and seal.
Therefore, some mechanic when installing a head gasket, mat in cylinder coated with a layer of butter, thought it can increase the tightness of diesel engine.
It seems to do little imagine, affected the performance of diesel engine.
Cylinder pad is one of the most important seal between diesel engine cylinder block and cylinder head, it can not only high temperature and high pressure gas produced by sealed inside the cylinder, and still can seal the cylinder head and cylinder of the cooling water and lubricating oil, therefore, when the mounting head gasket, pay special attention to its sealing quality.
If installed in the cylinder MATS and butter, when the cylinder head bolt is tightened, part of the butter will be squeezed into the cylinder in the channel and the oil duct, stay in the cylinder gasket between the butter in cylinder work, due to the effect of high temperature, part will shed cylinder combustion, others remain in the combination of the cylinder block and cylinder head, cylinder pad, cylinder head and the body plane between aperture, high temperature and high pressure gas from impact cylinder pad, easily damaged cylinder pad, cause air leakage.
In addition, the butter for a long time in high temperature condition also will produce carbon deposit, cylinder pad premature aging metamorphism.
So do not butter when install the cylinder pad.
3, cylinder liner and piston product without matching that installing a change in the cylinder liner and piston, thinks the new cylinder liner and piston are standard parts, are interchangeable, mount can use.
In fact, the size of the cylinder liner and piston has a certain tolerance range.
Such as the maximum size of the jacket with the minimum size of the piston, can make the fit clearance is too large, causing compression is weak, and start the difficulties.
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, each cylinder is installed in the same group code of cylinder liner and piston at the same time, also notice before test cylinder clearance, to ensure assembly standard, in front of the machine should also conduct a test, in case of mount defect of fake and shoddy products.
4, the cylinder clearance measurement in measuring cylinder clearance is not allowed, not in piston skirt is perpendicular to the direction of the piston pin hole measurement, and measurement in the other direction.
The structure characteristics of aluminum alloy piston is little big, is a cone, and the skirt section for elliptic, so along the circumferential direction of the cylinder clearance is not equal.
Measurement, the regulations will be subject to the direction of the long axis of the ellipse clearance, which measure the piston skirt in vertical direction of the piston pin hole clearance.
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, piston flame heating due to 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;
Piston surface also attach to ashes, reduce the service life of the piston.
If natural cooling after the piston reaches a certain temperature, its microstructure will be damaged and the wear-resisting performance is greatly reduced, its service life will be significantly reduced.
When installing a piston pin, piston can be placed in hot oil evenly heating make its slow inflation, must not use open flame heating directly.
6, with emery cloth grinding bearing bush for some inexperienced mechanic, scraping tile is a difficult work, because the scraping tile technology hard to master, so 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.