Engine overhaul process and matters needing attention

Reception process

1. The registration requirements are complete (especially the time and the number of kilometers are invalid for the odometer. If the customer does not agree to repair the factory written instructions, it will be calculated at 300 kilometers per day after leaving the factory, and 20,000 kilometers will exceed the warranty period.)
2. The engine is malfunctioning. (Regular oil leakage locations, frequent belt breaks (cylinder bed), frequent oil pressure instability, abnormal noise, etc.) Quality inspection and maintenance personnel explain the causes of the above locations in detail, and determine replacement. (For the exchangeable or non-exchangeable ones, we will communicate with customers and replace them at various levels, taking into account the factors of the warranty period after leaving the factory.)

Disassembly, washing and inspection process

1. Remove the cylinder head bolts. Note that the oil pan bolts or shell bolts must be in a cold state. They can be disassembled according to the ability to cross first and then close, so as to prevent the parts from deforming during the disassembly process and leaving hidden dangers.
2. If the problem of insufficient oil pressure is frequently reported, pay attention to the inside of the cylinder, especially whether there are micro cracks on the outside of the oil passage pipe diameter causing the inside. (Detection of oil pump pressure)
3. The journal data, cylinder journal data and the average position of journal oil should be tested cylinder by cylinder according to the requirements of the table, and the table should be filled in. (The arbitration of the Maintenance Office originally presented the original basis for the accident) Cylinder block and cylinder head plane unevenness Check the light leakage gap with a steel ruler to determine whether to shovel the flat surface. (Frequent oil leakage, gas blow-by failure). If the basic parts exceed the safety standard, contact the user in time to confirm the replacement. (Users do not agree to replace, and must sign: "Non-replacement maintenance agreement" to prevent future troubles. If there are frequent cylinder bed failures, consider 1. Whether the vehicle has repeatedly shoveled the cylinder block and the cylinder head plane condition, if any It is necessary to detect whether the height has exceeded the standard. It needs to be replaced (usually the cylinder head). If not, the plane (after light leakage detection) needs to be processed by outsourcing. Otherwise, it is easy to blast, and it is difficult to solve the problem of flushing the cylinder gasket.

Assembly process

1. Assembly environment, quality avoidance.
1.) Dirty venue
2.) External ring mirror for windy and sandy weather.
2. The required assembly procedure and torque of bolts (especially for Xikang vehicles, aluminum alloy cylinders, extremely large torque occurs, causing serious consequences for slipping ribbons).
3. The engine is precision-coordinated, and the current products are basically mature products. If there are abnormalities in the normal assembly, you should first consider whether there is any negligence or mistakes in the process in the re-inspection. Do not hit hard with your head and force the re-installation. Otherwise, the consequences will be incalculable. (D25 car engine Zhang X disassembles and reassembles allusions!)
4. Imported axle bushes are strictly prohibited from scraping. At present, the production vehicles are basically imported products from Sino-foreign joint ventures. The accuracy of the axle bushes is also not suitable for scraping. However, the clearance between the bush and the axle should also be disassembled and inspected during assembly, and a written assembly inspection record shall be made. (The gap is plugged, pressed, and the safety line method is used. The meshing surface can be printed and tested. It provides a basis for future accidents and accident prevention and solutions. If the gap is too large, the aperture of the connecting rod must be considered. The connecting rod is due to work The environment, frustration, pressure and cushion force influence, do not rule out deformation factors, detection methods. 1.) Make a table. 2.) Check the replacement parts and install the bearing bushes with new connecting rods for test. If the meshing surface is obviously the same as the original connecting rod, consider the diameter of the connecting rod. If the gap is too large, it can be dealt with by drilling the connecting rod cover. (You must weigh the connecting rod when purchasing. The error of the weight of the connecting rod in the same group should not be greater than 29 grams, otherwise it will cause the engine to run unstable and malfunction.
5. For cars with high water temperature (especially when the oil is milky white and has deteriorated), it is important to check the water pressure of the cylinder. ) Water seepage in the oil radiator, failure of the water pump, cracked or micro cracks in the cylinder liner are all within the detection range.
6. After the cylinder head is removed, check whether the multi-cylinder liner pulls the cylinder and whether the piston is missing. (Involving whether the connecting rod is twisted, bent, or deformed).
7. After changing the cylinder liner, changing and comparing the valve seat and processing, the main engineer must re-inspect, 1.) Whether there is any crack in the middle and lower part of the cylinder liner (to prevent the internal leakage of water from entering the oil pan after installation) 2. ) Whether the valve seat and the valve are broken, and the height is combined. (In case the seal is not tight, the cylinder pressure is insufficient, and the engine is weak and malfunctions). 3.) Because the processing technology of changing the cylinder block is difficult to ensure that the block will not fall off and cause the valve to break and the piston to malfunction, the user and the manufacturer must reach a written agreement in this type of situation to avoid future troubles. 4.) The position of the front and rear oil seals is deformed or leaked if worn. It needs to be repaired by welding and re-crepe the processing situation. The service station shall not be accepted. (Users are not willing to change the cylinder body to be processed) Because of its concentricity, it is difficult to meet the requirements under the current processing conditions.

Inspection (completion) process

1. Appearance inspection: all processes are based on reasons
2. Start-up inspection: 1.) Meter response 2.) Start-up response time 3.) Muffler exhaust smoke concentration, color 4.) Sound.
3. Running inspection, rapid-medium-high-speed speed changes, noise changes, (taboo: high-speed continuous operation for a long time to prevent cylinder pulling.
4. "Four leaks" inspection (air leakage, oil leakage, water leakage, electricity leakage)
5. Acoustic inspection, the root causes of abnormal noise are generally three situations: 1) improper fit clearance, 2) different mating mating surfaces, and 3) incorrect assembly and connection.
6. The test run time, the engine was originally required to be tested in the shop for no less than 4 hours, the loading pad test should be no less than 1 hour, and the road test should be no less than 30 kilometers.
7. Check the working conditions. After the oil pressure, water temperature and appearance are normal, the cylinder must be checked. If the original sound of the cylinder is not changed, check the working condition of the leaking nozzle to prevent the engine from being caused by the failure of the injector. Operation failure, (especially if the driver does not agree to repair the fuel nozzle and the fuel pump before maintenance, and make contact, communicate and deal with it.
8. The test run inspection result should be entered into the required items in the form. The basic proof of responsibility for quality inspectors and maintenance workers is that the data in the form reflect the true process and conclusions. If the quality inspectors do not fill in as required, they can change positions and become repairers. The technician in charge must observe on-site when assembling in the maintenance group. Eliminate illegal operations and cause quality hazards to the engine.

Delivery process

1. During the maintenance process, if the customer does not agree to replace the parts and purchase the parts by himself, the processing conditions must be signed and archived according to the existing "non-replacement maintenance agreement" and "self-purchasing maintenance agreement (including processing). Who is negligent? Responsible.)
2. After the engine is overhauled, instruct the customer and indicate the driving on the transfer car. Maintenance and oil change must be done at 2000 kilometers. It is required to change the oil every "10,000 kilometers" afterwards. (Xikang machine stipulates the oil change time according to the manufacturer's requirements) and requires the driver to be careful in the operation, “when driving at high speed for a long time and when the flame is turned off, the machine should run at a rapid speed to prevent the high temperature of the machine body from pulling the cylinder and damage to the pressure.
3. After the customer picks up the car and leaves the factory, if there is a phenomenon of "water temperature is too high" the engine lights up, the customer must be notified to stop driving and wait for rescue. It is impossible not to go to the scene and command indiscriminately, causing serious consequences to be compensated.