With the growth of the so-called output of domestic trucks, various car enterprises realize their share through different ways of competition; However, in the post market service system, the so-called super long warranty plan basically leads to the maintenance system of the whole truck industry becoming a huge replacement factory in a disguised form; This also leads to the wrong thinking mode of many car users that they change when they break down. At this stage, many repeated faults are often caused by this blind replacement of WD615.
Since automobile repair is called repair, it should be carried out under the condition of theoretical basis; Many factors may lead to parts damage. The damage is not terrible. What is terrible is blind replacement and wrong maintenance process (no ideas and theoretical basis).
The repeated bearing case of WD615 engine in recent days fully reflects the current situation of the truck maintenance industry:
A 2009 HOWO dump truck had a bearing accident a month ago. The repair shop only replaced 6 connecting rods, crankshafts, bearing shells and other parts for the so-called experience of the vehicle due to long-term overload. After maintenance, it was put into use for a week, and the bearing was held again. After taking simple photos, the pictures transmitted from the network are determined to be the current situation that the connecting rod bearing, rolling bearing and main bearing are strained and the crankshaft is half scrapped.
According to the on-site photos of the main bearing taken by the maintenance personnel, the powder fragments of the bearing bush are pressed and embedded on the surface of the main bearing bush at both ends close to the stop of the main bearing, and there are obvious signs of particle damage.
There are also obvious bright traces of foreign matter friction stroke on both sides of the main journal oil passage hole. The connecting rod journal of bearing bush belongs to the highest level of bearing bush + rolling bush, and the residue of bearing bush alloy pasted on the journal after melting is adhered to the outer surface of the journal.
In order to illustrate the lubricating oil supply system of conventional engine, we use the oil supply diagram of IVECO C13 series engine to illustrate:
In the above figure, after sucking the lubricating oil, the oil pump passes through the oil circuit of the oil pump to the water-cooled oil radiator, then enters the external rotary oil filter, and then returns to the main oil passage of the cylinder block. The main oil passage provides sufficient lubricating oil for the main bearing bush of the engine to ensure the lubricating oil required for the normal operation of the fully floating crankshaft. At the same time, the main oil passage passes through the pipeline to the auxiliary oil passage of the engine lubrication system, One of the auxiliary oil passages is to the oil nozzle to forcibly lubricate the piston. The connecting rod moving assembly is also connected with the oil passage to the camshaft. At the same time, the main and auxiliary oil passages also have a pipeline to the gear chamber for lubrication.
For WD615 engine, the main oil passage is not only supplied to the crankshaft, but also to the camshaft. However, no matter how it changes, the lubricating oil of the engine must be filtered through the oil radiator and oil filter before it can be supplied to each oil circuit.
Many card friends may ask, he is holding the tile. Do you want me to see the oil lubrication line? Generally speaking, many card friends think that as long as the oil pressure is enough, the engine will not hold the shoe, but this is also a special case, especially for the engine that used to hold the shoe, it is very important to understand the lubricating oil routing. Before we continue, let’s take a look at the small structure of the down rotating oil filter.
Since it is a filter, it is to filter the lubricating oil, leave impurities and let the clean lubricating oil enter the engine. However, there is a safety valve. Once the filter element is blocked, normally, if no oil enters the engine lubrication system, the probability of engine scrapping and major safety accidents of the vehicle is very high, As the saying goes, “it’s better to live than die”. So we’d rather sacrifice the engine. Even if the bearing bush is pulled, the vehicle doesn’t stop suddenly (of course, it’s hard to say if the cylinder is tamped). So once the safety valve is opened, the unclean lubricating oil (with impurities) will enter the oil passage of the lubrication system. It’s like burying a bomb!
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As mentioned earlier, the engine went to the repair shop for maintenance after holding the bush. There is a stress here, that is, whether the filter has been blocked, causing the oil sludge after the safety valve is opened and the bearing bush powder formed in the last holding the Bush to enter the oil passage. It was learned in the process of communicating with the user, The repair shop did not disassemble the oil duct plug of the engine, clean the main oil duct and auxiliary oil duct of the engine, and did not replace the oil cooler core and check the oil pump.
From the current situation of the vehicle, due to the serious rolling of connecting rod journal, main journal and main bearing bush, it is likely that the impurities in the oil passage enter the bearing bush gap, resulting in the destruction of the bearing bush gap between connecting rod and crankshaft connecting rod journal, resulting in local high temperature, local strain and high-temperature bonding of bearing bush, At this time, due to heavy load or other reasons, it did not stop in time, resulting in local strain and turning into a malignant accident of rolling tile.
In general, if there is a case of shoe holding, the oil filter and other components must be measured or even dissected during maintenance. Once the safety valve is opened, the engine must strictly clean the main and auxiliary oil passages before the remaining formal maintenance. Of course, if it is easy, the main and auxiliary oil passages must be cleaned as long as the engine with shoe holding, To eliminate the possibility of re bearing caused by residual impurities in the oil passage.
For engineering vehicles, the replacement of engine lubricating oil is not based on driving mileage, but on working hours. It is recommended that users should read the maintenance instructions more. At the same time, if they often walk on the road with a large slope, conditional users should modify the type of engine bipolar oil pump to avoid the case of lack of oil bearing pad caused by the failure of the oil pump to absorb lubricating oil on the slope.
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