Engine exhaust system oil leak detection method and apparatus

Abstract

This invention relates to a method and apparatus for detecting oil leakage in an engine exhaust system. The method includes adding fluorescent dye to the engine oil of the engine under test; connecting the engine under test to a dynamometer; controlling the engine under test to perform a warm-up operation, and then controlling the engine under test to operate at rated conditions for a first preset time after the warm-up operation is completed; controlling the engine under test to operate at low idle speed for a second preset time; after the engine under test completes low idle speed operation, detecting oil leakage based on the amount of external fluid leakage to obtain oil leakage detection results; and evaluating exhaust oil leakage based on the oil leakage detection results to obtain an exhaust oil leakage evaluation report. This invention solves the technical problems of being unable to identify the leakage medium, identify the leakage source, and pinpoint the faulty component by reproducing the leakage phenomenon of the exhaust system, using fluorescent dye to distinguish the leakage medium, and confirming the leakage source and identifying the faulty component through oil traces.

Description

Technical Field

[0001] This invention relates to the field of engine testing technology, and in particular to a method and apparatus for detecting oil leakage in an engine exhaust system. Background Technology

[0002] Under normal and stable engine operating conditions, the oil from the valve stem seals or combustion chamber is ignited by the high-temperature combustion gases and discharged through the exhaust pipe. There is no oil leakage in the engine exhaust system. However, during prolonged idling, the turbocharger speed drops significantly, resulting in insufficient intake pressure and incomplete combustion in the combustion chamber. This leads to a decrease in combustion gas pressure, reduced contact force between the piston rings and cylinder bores, and a deterioration in the seal between them. Consequently, the piston rings do not adequately scrape oil during the power stroke, resulting in an increased amount of residual oil on the cylinder walls after the power stroke. When the engine is idling, fuel consumption decreases, the internal combustion engine's heat dissipation decreases, the coolant temperature decreases, and the temperature inside the combustion chamber and exhaust pipe decreases. As a result, the oil vapor in the combustion chamber cannot be completely burned off and gradually condenses into liquid oil in the engine's exhaust system, flowing out of the exhaust pipe. Therefore, when the engine is idling for a long time, the excess oil leaking from the engine's exhaust valve stem seal or combustion chamber cannot be fully ignited or completely burned by the combustion gases. The unburned and partially burned oil adheres to the inner wall of the exhaust system and accumulates, eventually leading to oil leakage in the exhaust system.

[0003] Currently, there is no mature test method for engine exhaust system oil leakage in the industry. Generally, passive visual inspection methods are used to inspect the engine, which cannot reproduce the leakage phenomenon of the exhaust system, identify the leakage medium, identify the source of the leakage, and pinpoint the faulty component. Summary of the Invention

[0004] In view of this, it is necessary to provide a method and device for detecting engine exhaust system oil leaks, so as to solve the technical problems in current engine exhaust system leak detection that cannot identify the leaking medium, identify the source of the leak, and pinpoint the faulty component.

[0005] To address the above problems, this invention provides a method for detecting oil leakage in an engine exhaust system, comprising:

[0006] Add fluorescent dye to the engine oil of the engine to be tested;

[0007] Connect the engine under test to the dynamometer;

[0008] The engine under test is controlled to perform a warm-up operation, and after the warm-up operation is completed, the engine under test is controlled to operate under rated conditions for a first preset time.

[0009] The engine under test is controlled to operate at a low idle speed for a second preset time.

[0010] After the engine under test completes low idling, oil leakage is detected based on the amount of external fluid leakage to obtain the oil leakage detection result.

[0011] Based on the oil leak detection results, an exhaust oil leak assessment is conducted to obtain an exhaust oil leak assessment report.

[0012] Optionally, the step of detecting oil leaks based on the amount of external fluid leakage to obtain oil leak detection results includes:

[0013] The engine under test is shut down and its exhaust system is inspected to determine whether there is any external leakage of fluid in the exhaust system.

[0014] If the leaking fluid exists and the leaking fluid exceeds a preset fluid threshold, then the exhaust manifold is removed;

[0015] The leaking fluid was examined using black light to determine whether it was engine oil.

[0016] When the leaking fluid is determined to be engine oil, the location of the oil leak is determined by inspecting the exhaust pipe, turbocharger, exhaust valve stem oil seal, cylinder head, and power cylinder, and the location of the oil leak and its corresponding leakage amount are recorded.

[0017] Optionally, determining the location of the oil leak by inspecting the exhaust pipe, turbocharger, and cylinder head includes:

[0018] Inspect the exhaust pipe and the turbocharger;

[0019] If there is no trace of oil flow through the exhaust pipe and there is oil deposit inside the turbocharger, then the turbocharger is the location of the oil leak.

[0020] If there is no oil deposit in the turbocharger, check the exhaust valve stem oil seal, the cylinder head, and the power cylinder. Determine the location of the oil leak by observing the flow traces of the leaking oil.

[0021] Optionally, after controlling the engine under test to stop and inspecting the exhaust system of the engine under test to determine whether there is a leaking fluid outside the exhaust system, the method further includes:

[0022] If there is no leaking fluid or the leaking fluid does not exceed the preset fluid threshold, then return to the step of controlling the engine under test to operate under rated conditions for a first preset time, and continue to perform the oil leak detection until there is no leaking fluid or the leaking fluid does not exceed the preset fluid threshold twice, confirming that the engine under test does not have an exhaust leak problem.

[0023] Optionally, after inspecting the leaking fluid with black light to determine whether the leaking fluid is engine oil, the method further includes:

[0024] If it is confirmed that the leaking fluid is not engine oil, then the leaking fluid is determined to be fuel or coolant by observing the turbine and the exhaust manifold connected to the turbine.

[0025] When the leaking fluid is fuel, it indicates a fuel system malfunction;

[0026] When the leaking fluid is coolant, it indicates that the cylinder head has a crack or the EGR system has failed.

[0027] Optionally, after determining that the leaking fluid is engine oil, and after identifying the location of the oil leak by inspecting the exhaust pipe and turbocharger, and recording the location of the oil leak and its corresponding leakage amount, the method further includes:

[0028] Reinstall the exhaust pipe and replace the gasket, then return to the step of controlling the engine under test to operate under rated conditions for a first preset time, and perform the oil leak detection multiple times to repeatedly verify the oil leak detection.

[0029] Optionally, the exhaust oil leakage assessment report includes the engine's serial number, test date, test parameters, PAM number, equipment information, exhaust port location, exhaust port linear range, exhaust port surface coverage, valve stem information, and oil source information.

[0030] Optionally, before connecting the engine under test to the dynamometer, the method further includes:

[0031] The engine under test was cleaned, and a pad was placed under the engine to indicate any fluid leakage.

[0032] Optionally, before adding the fluorescent dye to the engine oil of the engine to be tested, the method further includes:

[0033] When the engine under test is a new engine that has never been run before, the engine under test is subjected to a long-term break-in operation.

[0034] Furthermore, the present invention also provides an engine exhaust system oil leakage detection device, comprising:

[0035] A dye addition module is used to add fluorescent dyes to the engine oil of the engine under test.

[0036] The connection module connects the engine under test to the dynamometer;

[0037] An engine control module is used to control the engine under test to perform a warm-up operation, and after the warm-up operation is completed, to control the engine under test to operate under rated conditions for a first preset time.

[0038] The idle speed control module is used to control the engine under test to operate at a low idle speed for a second preset time.

[0039] The leak detection module is used to detect oil leaks based on the amount of external fluid leakage after the engine under test has completed low idling operation, and to obtain the oil leak detection results.

[0040] The detection and evaluation module is used to evaluate exhaust oil leakage based on the oil leakage detection results and obtain an exhaust oil leakage evaluation report.

[0041] The beneficial effects of the above embodiments are as follows: The engine exhaust system oil leakage detection method provided by the present invention involves adding fluorescent dye to the engine oil of the engine under test; connecting the engine under test to a dynamometer; controlling the engine under test to perform a warm-up operation, and after the warm-up operation is completed, controlling the engine under test to operate at rated conditions for a first preset time; controlling the engine under test to operate at low idle speed for a second preset time; after the engine under test completes low idle speed operation, performing oil leakage detection based on the external fluid leakage amount to obtain oil leakage detection results; and performing exhaust oil leakage assessment based on the oil leakage detection results to obtain an exhaust oil leakage assessment report. The present invention solves the technical problem of being unable to identify the leakage medium, identify the leakage source, and pinpoint the faulty component in engine exhaust system leakage detection by reproducing the exhaust system leakage phenomenon, using fluorescent dye to distinguish the leakage medium, and confirming the leakage source and identifying the faulty component through oil traces. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating an embodiment of the engine exhaust system oil leakage detection method provided by the present invention;

[0044] Figure 2 This is a flowchart illustrating an embodiment of step S105 of the engine exhaust system oil leakage detection method provided by the present invention.

[0045] Figure 3 A schematic flowchart of an embodiment of step S204 of the engine exhaust system oil leakage detection method provided by the present invention;

[0046] Figure 4 This is a flowchart illustrating an embodiment of the engine exhaust system oil leakage detection method provided by the present invention after step S203;

[0047] Figure 5 This is a schematic diagram of an embodiment of the engine exhaust system oil leakage detection device provided by the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] It should be understood that the illustrative drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0050] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0051] This invention provides a method and apparatus for detecting oil leakage in an engine exhaust system, which will be described below.

[0052] Figure 1 This is a schematic flowchart of an embodiment of the engine exhaust system oil leakage detection method provided by the present invention, as shown below. Figure 1 As shown, it includes:

[0053] S101. Add fluorescent dye to the engine oil of the engine to be tested;

[0054] S102. Connect the engine to be tested to the dynamometer;

[0055] S103. Control the engine under test to perform a warm-up operation, and after the warm-up operation is completed, control the engine under test to operate under rated conditions for a first preset time.

[0056] S104. Control the engine under test to run at a low idle speed for a second preset time.

[0057] S105. After the engine under test completes low idling, perform oil leakage detection based on the amount of external fluid leakage to obtain the oil leakage detection result.

[0058] S106. Based on the oil leakage detection results, conduct an exhaust oil leakage assessment to obtain an exhaust oil leakage assessment report.

[0059] Compared with existing technologies, the engine exhaust system oil leakage method provided by this invention involves adding fluorescent dye to the engine oil of the engine under test; connecting the engine under test to a dynamometer; controlling the engine under test to perform a warm-up operation, and then controlling the engine under test to operate at rated conditions for a first preset time after the warm-up operation is completed; controlling the engine under test to operate at low idle speed for a second preset time; after the engine under test completes low idle speed operation, oil leakage detection is performed based on the amount of external fluid leakage to obtain oil leakage detection results; and exhaust oil leakage is assessed based on the oil leakage detection results to obtain an exhaust oil leakage assessment report. This invention solves the technical problems of not being able to identify the leakage medium, identify the leakage source, and pinpoint the faulty component in engine exhaust system leakage detection by reproducing the exhaust system leakage phenomenon, using fluorescent dye to distinguish the leakage medium, and confirming the leakage source and identifying the faulty component through oil traces.

[0060] Understandably, in practice, to reproduce the exhaust system leakage phenomenon, a dynamometer is connected to the engine. Before testing, the engine is warmed up to prepare for full-load operation. After warm-up, the engine is run at rated speed and load for 30 minutes (first preset time), with the following engine parameters: intake manifold temperature = 115±5℉, fuel temperature = 100±10℉, and coolant temperature = 190±5℉. This ensures a sufficiently high exhaust temperature to burn off any oil present in the exhaust system and to bring the engine oil temperature to a typical operating condition. After completing the above operations, the engine is controlled to run at low idle speed without load for 12 hours (second preset time). To prevent the engine shutdown function from being activated during low idle operation, the shutdown function can be turned off or activated via PTO (Power Take-Off). Off (power output device) keeps the engine running at the lowest stable speed; some engines under test include a "cylinder balance algorithm", and if the engine calibration includes this algorithm, this function also needs to be turned off; unnecessary mechanical or electronic accessories also need to be turned off and torque and oil pan temperature recorded, and fluid leak detection is performed after the engine operating conditions are reproduced.

[0061] It should be understood that, in the embodiments of the present invention, different engines have different exhaust oil leakage at different low idle speeds. Therefore, before the test, it is necessary to determine the idle speed at which the engine oil leakage is most severe according to the specific engine model. If the engine under test has no oil leakage at low idle speed, the exhaust oil leakage test is carried out again at 1.5 to 2 times the low idle speed in order to simulate the worst operating conditions of the engine.

[0062] In some embodiments of the present invention, reference is made to... Figure 2 , Figure 2 This is a flowchart illustrating an embodiment of step S105 of the engine exhaust system oil leakage detection method provided by the present invention. Step S105 includes:

[0063] S201. Control the engine under test to stop and check the exhaust system of the engine under test to determine whether there is any leakage fluid outside the exhaust system;

[0064] S202. If the leaking fluid exists and the leaking fluid exceeds a preset fluid threshold, then the exhaust manifold is removed.

[0065] S203. Inspect the leaking fluid with black light to determine whether the leaking fluid is engine oil;

[0066] S204. When it is determined that the leaking fluid is engine oil, the location of the engine oil leak is determined by inspecting the exhaust pipe, turbocharger, exhaust valve stem oil seal, cylinder head and power cylinder, and the location of the engine oil leak and its corresponding leakage amount are recorded.

[0067] It should be noted that the preset fluid threshold refers to the maximum allowable leakage flow rate of the engine exhaust system. In this embodiment of the invention, after 12 hours of low-idle operation, the engine under test is stopped, and the exterior of the exhaust system is inspected. If a large amount of leaking fluid is found outside the exhaust system, significantly exceeding the preset fluid threshold, the exhaust manifold and turbocharger are removed from the engine as a whole. It is necessary to ensure that no oil leaks into the exhaust manifold before and after removal to ensure the accuracy of the oil leakage traces on the exhaust manifold. The leaking fluid is then illuminated with black light. If the leaking fluid contains oil with added fluorescent dye, it can be identified with the naked eye. If the leaking fluid is oil, a more in-depth inspection is conducted on engine components such as the exhaust pipe, turbocharger, exhaust valve stem oil seal, cylinder head, and power cylinder. Based on the inspection results, the leak location is determined and the faulty component is identified.

[0068] In some embodiments of the present invention, reference is made to... Figure 3 , Figure 3 This is a schematic flowchart of an embodiment of step S204 of the engine exhaust system oil leakage detection method provided by the present invention. Step S204 includes:

[0069] S301. Inspect the exhaust pipe and the turbocharger;

[0070] S302. If there is no trace of oil flow through the exhaust pipe and there is oil deposit in the turbocharger, then the turbocharger is the location of the oil leak.

[0071] S303. If there is no oil deposit in the turbocharger, check the exhaust valve stem oil seal, the cylinder head, and the power cylinder. Determine the location of the oil leak by observing the flow traces of the leaking oil.

[0072] It should be noted that in this embodiment of the invention, it is first necessary to verify whether there is a separate oil deposit at the turbocharger outlet. If not, the turbocharger is not the source of exhaust oil leakage. If there is oil deposit in the turbocharger, but there is no trace of oil flowing through the corresponding exhaust pipe, it indicates that the oil comes from the turbocharger. In this case, the fault diagnosis is a turbocharger fault, and the turbocharger may need to be replaced.

[0073] In some embodiments of the present invention, after step S201, the method further includes:

[0074] If there is no leaking fluid or the leaking fluid does not exceed the preset fluid threshold, then return to the step of controlling the engine under test to operate under rated conditions for a first preset time, and continue to perform the oil leak detection until there is no leaking fluid or the leaking fluid does not exceed the preset fluid threshold twice, confirming that the engine under test does not have an exhaust leak problem.

[0075] It should be noted that, in this embodiment of the invention, if there is no leaking fluid or only a very small amount of leaking fluid outside the engine exhaust system, at least two reproduction operations of the engine exhaust system leakage condition need to be performed, that is, multiple tests and checks are conducted to ensure the accuracy of the test results.

[0076] In some embodiments of the present invention, reference is made to... Figure 4 , Figure 4 This is a flowchart illustrating an embodiment of the engine exhaust system oil leakage detection method provided by the present invention after step S203. After step S203, the method further includes:

[0077] S401. If it is confirmed that the leaking fluid is not engine oil, then determine whether the leaking fluid is fuel or coolant by observing the turbine and the exhaust manifold connected to the turbine.

[0078] S402. When the leaking fluid is fuel, it indicates a fuel system malfunction.

[0079] S403. When the leaking fluid is coolant, it indicates that the cylinder head has a crack or the EGR system has failed.

[0080] It should be noted that, in this embodiment of the invention, after determining that the leaking fluid is not engine oil, the leaking fluid needs to be identified. The leaking fluid is generally fuel or coolant. Fuel can be identified by smell. Alternatively, the turbine and the exhaust pipe connected to the turbine can be inspected to observe whether there is carbon deposit or oil smoke inside. If so, it indicates that the leaking fluid is fuel. If there are fluid spots at the exhaust pipe opening, it can be determined that the fuel system is faulty. If the inside of the exhaust pipe opening is clean and shiny, it indicates that the leaking fluid is coolant, and it can be determined that the cylinder head is cracked or the EGR (Exhaust Gas Return) system is malfunctioning.

[0081] It should also be noted that, in this embodiment of the invention, if the engine cylinder head supports dry operation, the oil leakage from the power cylinder can be determined by the proportion of the oil leakage from the power cylinder to the total oil leakage from the exhaust. If the cylinder head does not support dry operation, the oil leakage trajectory needs to be observed. If the oil trajectory appears along the edge of the exhaust valve and is close to the sealing gasket, the source of the leakage is the power cylinder. If the oil trajectory is located at the top of the exhaust valve stem at the bottom of the exhaust valve guide, the source of the oil leakage is the cylinder head.

[0082] Understandably, if the engine under test experiences a significant oil leak within 30 seconds and its source cannot be identified (e.g., the entire valve is soaked in oil), the oil will quickly evaporate due to the vibration of the valve stem and the contact effect of the cleaning agent. In this case, the engine should be stopped for a few minutes to allow the cleaning agent to evaporate completely, until there is no confusion affecting the determination of the source of the exhaust oil leak after the engine is restarted. Restart the engine and run it at the same no-load speed for 5-10 seconds, then stop the engine and review the source of the exhaust oil leak. If there is not enough oil leakage to determine the main source of the exhaust oil leak after 30 seconds of idling, restart the engine and run it at the same speed for 1 minute, then turn it off. Check the oil in the exhaust port and record the location of the exhaust port where the oil leak occurred and its source. Continue to run the engine under no-load conditions for one minute, while checking the exhaust oil leak between each test until the main source of the leak (power cylinder or cylinder head) is clear. If there is no oil leak after multiple one-minute tests, then perform an exhaust oil leak test at a higher idle speed.

[0083] In some embodiments of the present invention, after step S204, the method further includes:

[0084] Reinstall the exhaust pipe and replace the gasket, then return to the step of controlling the engine under test to operate under rated conditions for a first preset time, and perform the oil leak detection multiple times to repeatedly verify the oil leak detection.

[0085] In some embodiments of the present invention, the exhaust oil leakage assessment report includes the serial number of the engine under test, the test date, test parameters, PAM number, equipment information, exhaust port location, exhaust port linear range, exhaust port surface coverage, valve stem information, and oil source information.

[0086] It should be noted that, in this embodiment of the invention, after completing an exhaust manifold leak test, an assessment of exhaust oil leakage is required. Due to the subjectivity of exhaust oil leakage assessment, it is recommended that one person complete all assessments. The test description includes any specific parameters related to the exhaust manifold leak test, such as low idle speed and low idle time. It is also necessary to record the number of PAMs (data stations from all computer systems) that are completely consumed or idle during the leak test. When the engine has two exhaust valves per cylinder, the positions of the two exhaust valves in each cylinder on the power cylinder should be marked. The exhaust port linear range refers to the length of the oil leakage trajectory from the valve to the cylinder head or exhaust manifold edge. The exhaust port surface coverage refers to the coverage area of ​​oil leakage at each exhaust port, including the area from the entire exhaust port to the cylinder head or exhaust manifold interface edge. Valve stem information is used to describe the condition of the oil on the valve stem (such as fully wet, streaked, bottom wet, top wet, etc.). The assessment report should also record the exhaust leak location and leak level.

[0087] In some embodiments of the present invention, before step S102, the method further includes:

[0088] The engine under test was cleaned, and a pad was placed under the engine to indicate any fluid leakage.

[0089] Understandably, cleaning the engine under test and setting up the gasket is to facilitate observation of oil leaks and to identify other influencing factors. The engine needs to be painted black so that a light-colored paint can be sprayed on the exhaust pipe side to make the oil leak clearly visible.

[0090] In some embodiments of the present invention, before step S101, the method further includes:

[0091] When the engine under test is a new engine that has never been run before, the engine under test is subjected to a long-term break-in operation.

[0092] It is understood that in the embodiments of the present invention, some new engines (or old engines equipped with new power system components) will not exhibit exhaust leakage during testing, but will gradually develop leakage during the break-in process of the power system components. Therefore, an engine needs a considerable period of break-in time before performing the exhaust oil leakage test. For the exhaust oil leakage test, the extremely high cylinder pressure (higher than the general technical requirements) and extremely high piston temperature (higher than the maximum fuel consumption) will cause permanent piston deformation. Such high pressure and high temperature are detrimental to the test itself and the results. Therefore, if the engine under test is a new engine, it needs to be run for 100 hours under this pressure and high temperature before the test to perform engine break-in operation.

[0093] Reference Figure 5 This embodiment also provides an engine exhaust system oil leakage detection device 500, which includes:

[0094] The dye addition module 501 is used to add fluorescent dye to the engine oil of the engine to be tested;

[0095] The connection module 502 connects the engine under test to the dynamometer;

[0096] The engine control module 503 is used to control the engine under test to perform a warm-up operation, and after the warm-up operation is completed, control the engine under test to operate under rated conditions for a first preset time.

[0097] Idle speed control module 504 is used to control the engine under test to run at low idle speed for a second preset time.

[0098] Leakage detection module 505 is used to detect oil leakage based on the amount of external fluid leakage after the engine under test has completed low idling operation, and to obtain oil leakage detection results.

[0099] The detection and evaluation module 506 is used to evaluate exhaust oil leakage based on the oil leakage detection results and obtain an exhaust oil leakage evaluation report.

[0100] The engine exhaust system oil leakage detection device provided in the above embodiments can realize the scheme described in the above embodiment of the engine exhaust system oil leakage detection method. The specific principle of each unit can be referred to the embodiment of the engine exhaust system oil leakage detection method, which will not be repeated here.

[0101] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0102] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting oil leakage in an engine exhaust system, characterized in that, include: Add fluorescent dye to the engine oil of the engine to be tested; Connect the engine under test to the dynamometer; The engine under test is controlled to perform a warm-up operation, and after the warm-up operation is completed, the engine under test is controlled to operate under rated conditions for a first preset time. The engine under test is controlled to operate at a low idle speed for a second preset time. After the engine under test completes low idling, oil leakage is detected based on the amount of external fluid leakage to obtain the oil leakage detection result. Based on the oil leak detection results, an exhaust oil leak assessment is performed to obtain an exhaust oil leak assessment report. The step of detecting engine oil leaks based on external fluid leakage to obtain engine oil leak detection results includes: controlling the engine under test to stop and inspecting the exhaust system of the engine under test to determine whether there is leaking fluid outside the exhaust system; if there is leaking fluid and the leaking fluid exceeds a preset fluid threshold, then removing the exhaust manifold; inspecting the leaking fluid with black light to determine whether the leaking fluid is engine oil; when the leaking fluid is determined to be engine oil, determining the location of the engine oil leak by inspecting the exhaust pipe, turbocharger, exhaust valve stem oil seal, cylinder head, and power cylinder, and recording the location of the engine oil leak and its corresponding leakage amount.

2. The method for detecting engine exhaust system oil leakage according to claim 1, characterized in that, The method of determining the location of oil leaks by inspecting the exhaust pipe, turbocharger, and cylinder head includes: Inspect the exhaust pipe and the turbocharger; If there is no trace of oil flow through the exhaust pipe and there is oil deposit inside the turbocharger, then the turbocharger is the location of the oil leak. If there is no oil deposit in the turbocharger, check the exhaust valve stem oil seal, the cylinder head, and the power cylinder. Determine the location of the oil leak by observing the flow traces of the leaking oil.

3. The method for detecting engine exhaust system oil leakage according to claim 1, characterized in that, After controlling the engine under test to stop and inspecting the exhaust system of the engine under test to determine whether there is a fluid leak outside the exhaust system, the method further includes: If there is no leaking fluid or the leaking fluid does not exceed the preset fluid threshold, then return to the step of controlling the engine under test to operate under rated conditions for a first preset time, and continue to perform the oil leak detection until there is no leaking fluid or the leaking fluid does not exceed the preset fluid threshold twice, confirming that the engine under test does not have an exhaust leak problem.

4. The method for detecting engine exhaust system oil leakage according to claim 1, characterized in that, After inspecting the leaking fluid with black light to determine whether the leaking fluid is engine oil, the process further includes: If it is confirmed that the leaking fluid is not engine oil, then the leaking fluid is determined to be fuel or coolant by observing the turbine and the exhaust manifold connected to the turbine. When the leaking fluid is fuel, it indicates a fuel system malfunction; When the leaking fluid is coolant, it indicates that the cylinder head has a crack or the EGR system has failed.

5. The method for detecting engine exhaust system oil leakage according to claim 1, characterized in that, When the leaking fluid is determined to be engine oil, after identifying the location of the oil leak by inspecting the exhaust pipe and turbocharger, and recording the location of the oil leak and its corresponding leakage amount, the method further includes: Reinstall the exhaust pipe and replace the gasket, then return to the step of controlling the engine under test to operate under rated conditions for a first preset time, and perform the oil leak detection multiple times to repeatedly verify the oil leak detection.

6. The method for detecting engine exhaust system oil leakage according to claim 1, characterized in that, The exhaust oil leakage assessment report includes the engine's serial number, test date, test parameters, PAM number, equipment information, exhaust port location, exhaust port linear range, exhaust port surface coverage, valve stem information, and oil source information.

7. The method for detecting engine exhaust system oil leakage according to claim 1, characterized in that, Before connecting the engine under test to the dynamometer, the process also includes: The engine under test was cleaned, and a pad was placed under the engine to indicate any fluid leakage.

8. The method for detecting engine exhaust system oil leakage according to claim 1, characterized in that, Before adding the fluorescent dye to the engine oil of the engine under test, the process also includes: When the engine under test is a new engine that has never been run before, the engine under test is subjected to a long-term break-in operation.

9. An engine exhaust system oil leakage detection device, characterized in that, include: A dye addition module is used to add fluorescent dyes to the engine oil of the engine under test. The connection module connects the engine under test to the dynamometer; An engine control module is used to control the engine under test to perform a warm-up operation, and after the warm-up operation is completed, to control the engine under test to operate under rated conditions for a first preset time. The idle speed control module is used to control the engine under test to operate at a low idle speed for a second preset time. The leak detection module is used to detect oil leaks based on the amount of external fluid leakage after the engine under test has completed low idling operation, and to obtain the oil leak detection results. The detection and evaluation module is used to evaluate exhaust oil leakage based on the oil leakage detection results and obtain an exhaust oil leakage evaluation report. The step of detecting engine oil leaks based on external fluid leakage to obtain engine oil leak detection results includes: controlling the engine under test to stop and inspecting the exhaust system of the engine under test to determine whether there is leaking fluid outside the exhaust system; if there is leaking fluid and the leaking fluid exceeds a preset fluid threshold, then removing the exhaust manifold; inspecting the leaking fluid with black light to determine whether the leaking fluid is engine oil; when the leaking fluid is determined to be engine oil, determining the location of the engine oil leak by inspecting the exhaust pipe, turbocharger, exhaust valve stem oil seal, cylinder head, and power cylinder, and recording the location of the engine oil leak and its corresponding leakage amount.

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