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Maintenance case: diesel engine "back to water" how to solve?
June 23, 2022
Diesel engine "back to the water", generally refers to the phenomenon of a large amount of gas generated inside the engine, resulting in a large amount of coolant overflow from the water tank mouth. Cause a large amount of gas inside the engine, one is the engine cylinder gasket damage, high-pressure gas in the cylinder into the cooling system; another reason is the engine in the high water temperature state suddenly stop or load is too large, resulting in internal engine overheating, a large amount of coolant gasification.
A 200KW diesel generator set "back to water" failure, our company immediately dispatched professional after-sales service personnel to repair.
Failure phenomenon and analysis
Diesel engine "back to water", generally refers to the phenomenon of a large amount of gas generated inside the engine, resulting in a large amount of coolant overflow from the water tank mouth. Cause a large amount of gas inside the engine, one is the engine cylinder gasket damage, cylinder high-pressure gas into the cooling system; another reason is the engine in the high water temperature state suddenly stop or load too much, resulting in internal overheating of the engine, a large amount of coolant vaporization.
The scene observation, the fault engine does not exist cylinder gasket damage or water overheating phenomenon, coolant is only a small amount of overflow, and in the engine running process to open the water tank cover, coolant instead of overflow. Therefore, it is judged that the fault is not the usual sense of "water", but due to the process of adding water, did not drain the air in the cooling system, the water temperature rises further, the cooling system gas heat expansion top open the tank cover, while bringing out a small amount of coolant and caused by a "water leak "phenomenon. To solve this problem, the first thing to do is to remove the air in the cooling system clean. The coolant will be released, re-added slowly, and pay attention to the discharge of air in the engine intercooler, the test found that the water temperature rose to about 70 ℃, there are still most of the units have "water leakage". At this time, the maintenance personnel noticed that this batch of units had added fuel-based coolant heating cold start device on the basis of the conventional configuration, and the cold start device took water at the warm air port of the engine, and the pipeline was long, so it was likely that the air inside this part of the pipeline was not easy to be drained.
According to the above analysis, considering that the cold start device takes water from the engine body, which cannot be changed, and the installation space is affected, the location and piping of the cold start device is not convenient to change, and there is no ideal location for adding an overflow tank, so it was decided to solve this problem by improving the exhaust capacity of the water tank.
The water tank mouth up 30 mm higher, down to extend 60 mm (the lower end of about in the middle of the upper water chamber), while in the downward extension of the section, near the top of the upper water chamber to open a 10 mm diameter exhaust hole. Downward extension section can ensure that the water flow inside the upper water chamber away from the tank mouth, so that the tank mouth inside to keep calm; upward raised section can make the tank in the gas-water mixture in the overflow rise process has a separation process, so that the gas floats to the top, top open the tank mouth check valve after overflow, coolant is back to the upper water chamber, will not be carried out. Exhaust hole can ensure that the water level is higher than the lower port of the water tank mouth, discharged into the tank.
Through the solution of this problem, it can be seen that the use of the improved structure of the water tank mouth described in this paper, can be used as one of the solutions to prevent the user from adding water in the process of the overflow caused by the lack of gas, of course, such as installation space allows the addition of overflow tank, is also a way to solve this problem, the user can change depending on the situation.
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