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4、(outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2795_201408SURFACE VEHICLEINFORMATION REPORTJ2795REV.AUG2014Issued 2012-12 Revised
5、2014-08 Superseding J2795 APR2007Power Cylinder Oil Consumption: Problem Solving RATIONALENew engineers or engineers that are not experienced in power cylinder development may not always have the necessary background to develop the optimum engines or solve problems that are experienced. This documen
6、t gives basic background information that will help engineers working with power cylinders with the knowledge that they need to help them be more effective. TABLE OF CONTENTS 1. SCOPE 31.1 Purpose . 32. REFERENCES 43. DEFINITIONS . 44. LIST OF METHODS 45. CHECK THE HISTORY OF THE ENGINE . 46. ELIMIN
7、ATE THE SIMPLE POSSIBILITIES (BEFORE ENGINE TEARDOWN) . 46.1 Check for Leaks 46.2 Check for Excessive Oil Carry Over . 56.3 Check for Malfunctioning External Components 56.4 Check for Coolant in the Oil 56.5 Check for Fuel in the Oil . 56.6 Measure Blow-by 56.7 Compression Check 56.8 Leak Down Test
8、66.9 Borescope the Engine . 66.10 Examine the Color of the Exhaust 66.11 Complete an Oil Analysis 6SAE INTERNATIONAL J2795 Revised AUG2014 Page 2 of 21 7. ELIMINATE THE POTENTIAL MISTAKES (AFTER ENGINE TEARDOWN) 67.1 Incorrect or Missing Components . 67.1.1 Piston Rings 67.1.2 Incorrect Dip-stick .
9、67.2 Misassembled Power Cylinder Parts 67.2.1 Piston Rings 67.2.2 Broken Parts . 67.2.3 Abnormal Marks 77.2.4 Improperly Handled Rings 78. OIL CONSUMPTION AS A RESULT OF A FAILURE 78.1 Broken Rings . 78.2 Face Coating Failure . 88.3 Scuffed Power Cylinder 88.4 Carbon Deposits on the Piston Top Land
10、and Top Ring Groove . 98.4.1 Carbon Buildup on the Top Land 98.4.2 Carbon Buildup in the Top Ring Groove . 108.4.3 Carbon Tracking . 108.5 Excessive Wear 108.6 Debris 118.7 Lack of Lubrication 118.8 Bore Washing from the Fuel . 118.9 Oil Burning from the Cylinder Wall 119. CHECK FOR PROPER DESIGN 12
11、10. MODELING AND MAPPING . 1210.1 Cylinder Kit Dynamics . 1210.2 Engine Oil Consumption Steady State Mapping . 1311. COMPONENT SWAPPING AND VARIATION TECHNIQUES 1311.1 Swapping Technique 1411.2 Variation Technique 1412. SYSTEM SEPARATION . 1412.1 Isolating the Overhead 1412.2 Isolating the Turbochar
12、ger/Supercharger . 1412.3 Isolating the Fuel Pump 1412.4 Isolating the Crankcase Ventilation Systems 1512.5 Isolating the External Components . 1513. OTHER POSSIBLE FACTORS 1513.1 Customer Duty Cycle 1514. OIL CONSUMPTION PROBLEM SOLVING SEQUENCE OIL CONSUMPTIONHAS BECOME BAD 1514.1 Before Disassemb
13、ly of the Engine 1514.1.1 Check the History 1514.1.2 Investigate the Source 1514.1.3 Check for Problems 1514.2 Minimal Disassembly of the Engine 1614.3 Remove the Cylinder Head. 1614.4 Remove the Power Cylinder Components 1614.4.1 Check for Incorrect Installation Issues 1614.4.2 Check for Damage 161
14、4.4.3 Evaluate the Components . 1714.4.4 Check for Wear . 1714.4.5 Check for Manufacturing Issues . 17SAE INTERNATIONAL J2795 Revised AUG2014 Page 3 of 21 15. OIL CONSUMPTION PROBLEM SOLVING SEQUENCE OIL CONSUMPTION IS HIGHBUT ACCEPTABLE ON OTHER ENGINES . 1715.1 Before Disassembly of the Engine 171
15、5.1.1 Check the History 1715.1.2 Investigate the Source 1715.1.3 Check for Problems 1715.2 Minimal Disassembly of the Engine 1815.3 Remove the Cylinder Head. 1815.4 Remove the Power Cylinder Components 1815.4.1 Check for Assembly Issues . 1815.4.2 Check for Damage 1815.4.3 Evaluate the Components .
16、1915.4.4 Check for Manufacturing Issues . 1915.5 Swap Testing 1916. OIL CONSUMPTION PROBLEM SOLVING SEQUENCE OIL CONSUMPTION IS ALWAYS HIGH 1916.1 Before Disassembly of the Engine 1916.1.1 Check the History 1916.1.2 Investigate the Source 1916.2 Remove the Head . 2016.3 Remove the Power Cylinder Com
17、ponents 2016.3.1 Evaluate the Components . 2016.3.2 Check for Manufacturing Issues . 2016.4 Evaluate the Design 2016.5 Model the Power Cylinder Dynamics 2016.6 Variation Testing . 2017. NOTES 2117.1 Marginal Indicia . 21FIGURE 1 EXAMPLE OF DAMAGED TO THE THIRD LAND DUE TO INSTALLATION DAMAGE . 7FIGU
18、RE 2 EXAMPLE OF BROKEN PISTON RING 8FIGURE 3 EXAMPLE OF FAILED RING FACE COATINGS . 8FIGURE 4 EXAMPLE OF PISTON SCUFF 9FIGURE 5 EXAMPLE OF CARBON POLISHING 9FIGURE 6 EXAMPLE OF CARBON TRACKING CAUSED BY EXCESSIVE BORE DISTORTION . 10FIGURE 7 EXAMPLES OF EXCESSIVELY WORN RINGS 11FIGURE 8 EXAMPLE OF E
19、XCESSIVE POLISH DUE TO BORE WASHING OR OIL BURNING 12FIGURE 9 EXAMPLE OF INTER-RING GAS PRESSURE AND RING MOTION . 13FIGURE 10 EXAMPLE OF OIL CONSUMPTION MAPPING 131. SCOPE This document describes methodologies to determine the causes of high oil consumption caused by primarily the power cylinder sy
20、stem. 1.1 Purpose The oil consumption of an internal combustion engine is a significant performance attribute. The loss of engine oil through the combustion chamber is critical because it impacts the emissions signature of the engine and potentially poisons any exhaust gas after treatment devices. T
21、o the operator of the engine, the consumption of oil is an unnecessary and excessive cost of engine operation. While solving oil consumption problems, it is important to have a systematic way of determining the cause of the high oil consumption. Not all of the oil consumption problems are due to the
22、 power cylinder system. Other engine subsystems can contribute to the oil consumption of an engine which means that isolation of contributing systems is essential for diagnosing and eliminating the source of oil consumption. The purpose of this document is to review the various possible systematic m
23、ethods for solving oil consumption problems. SAE INTERNATIONAL J2795 Revised AUG2014 Page 4 of 21 2. REFERENCES There are no referenced publications specified herein. 3. DEFINITIONS There are no unique definitions. 4. LIST OF METHODS The following is a list of the basic methods for determining the c
24、auses of high oil consumption: x Check the History of the Engine x Eliminate the Simple Possibilities x Eliminate the Mistakes x Oil Consumption as a Result of a Failure x Modeling and Mapping x Component Swapping and Variation Techniques x System Separation 5. CHECK THE HISTORY OF THE ENGINE High o
25、il consumption may be a result of how the engine was operating. Make sure that the engine was run properly. Some of the areas to check on engine operation are: x Check for changes to blow-by. This might indicate a problem in the engine. x Check the history for changes in temperatures and/or pressure
26、s that might indicate incorrect engine operation or problems:x Oil x Coolant x Intake x Exhaust x Check the condition of the oil for signs of potential problems. Example of lubrication conditions to analyze are: x Oxidation parameters x Viscosity x Wear Metals x Contaminants x Check for incorrect en
27、gine operation: x Speed x Load 6. ELIMINATE THE SIMPLE POSSIBILITIES (BEFORE ENGINE TEARDOWN) When there is a problem with high oil consumption of an engine, it is important to eliminate the simple potential causes first. These are the things that are done prior to any engine teardown. 6.1 Check for
28、 Leaks In any case where there is high oil consumption, an examination of leaks should be made. Look for oil on the ground or oil on the engine. The magnitude of the leak might be determined by catching the oil leaked over a period of time and measuring the final quantity. SAE INTERNATIONAL J2795 Re
29、vised AUG2014 Page 5 of 21 6.2 Check for Excessive Oil Carry Over Oil may exit through the crank case breather. In an open system, the oil may then accumulate on the ground. In a closed system there may be oil in the intake system. Excessive oil through the breather might be an indication of various
30、 problems:Design Issues x Poorly Designed Breather x Incorrectly Positioned Breather x Plugged Breather or Valve (PCV) x Missing Breather or Valve (PCV) Problemsx Might indicate excessively high blow-by that results from a power cylinder problem 6.3 Check for Malfunctioning External Components Compo
31、nents other than the power cylinder may contribute to high oil consumption. Check these components for signs of oil consumption problems. Turbocharger/Supercharger Can often be isolated from the main engine to determine the turbocharger/supercharger contribution to oil consumption. Oil tracks might
32、also be seen in the outlet if there is a broken seal. Air compressor Might be able to remove from the engine to check for its contribution to oil consumption. Valve Guides There may be oil leaking down the valve stems. Replace the valve stem seals if possible. Fuel Pump The fuel pump or fuel injecto
33、rs may leak oil into the fuel. The oil will then be burnt with the fuel. 6.4 Check for Coolant in the Oil Coolant in the cylinder will vaporize causing high blow-by. Also it will affect lubricity of the oil and result in high wear ofthe cylinder walls that will affect blow-by and oil consumption. Co
34、olant in the oil could also indicate a failed cylinder head gasket which could cause high blow-by and / or oil consumption. 6.5 Check for Fuel in the Oil Fuel in the oil will affect the lubricity of the oil and result in high wear of the cylinder walls that will affect blow-by. 6.6 Measure Blow-by M
35、easure blow-by in the problem solving efforts. High blow-by might be an indicator of power cylinder issues that might result in high oil consumption also. These issues could include: x Broken Ring x Broken Piston x Scuffed Cylinder 6.7 Compression Check A compression check can help to determine if t
36、here is a problem with the rings or pistons that might be resulting in high oil consumption.SAE INTERNATIONAL J2795 Revised AUG2014 Page 6 of 21 6.8 Leak Down Test A leak down test can follow a compression check to identify the source of the leak. Look for signs of leaking in the intake ports, exhau
37、st ports, crankcase, or coolant. Signs for leaks may be leakage noise in the ports and crankcase, or gas bubbles in the coolant. This test makes it possible to better understand whether the power cylinder (piston and rings) is the source of blow-by that might be affecting oil consumption. 6.9 Boresc
38、ope the Engine A borescope of the cylinder will help to identify if there has been scuffing or piston damage that might explain the cause of high oil consumption. 6.10 Examine the Color of the Exhaust The color of the exhaust gases might indicate problems: x Excessive white smoke might indicate cool
39、ant in the cylinder x Excessive black smoke might indicate excessive fuel. 6.11 Complete an Oil Analysis Analyze the oil for signs of potential problems. Analyze viscosity change and base number change for oil degradation. Check for wear metals (iron, chrome, etc.) in the oil for indications of fail
40、ures occurring within the engine. The oil should also be analyzed for contaminates such as fuel and coolant. Excessive fuel or coolant in the oil may diminish the lubricity which will cause excessive wear or scuffing of the cylinder. This can result in high oil consumption. 7. ELIMINATE THE POTENTIA
41、L MISTAKES (AFTER ENGINE TEARDOWN) 7.1 Incorrect or Missing Components Verify that there are no incorrect or missing components in the engine. 7.1.1 Piston Rings Check each ring. Have all the rings been installed on each piston? Have the correct piston rings been used. Make sure that the oil rings a
42、re installed with all the pieces. A missing piece can be detrimental to oil consumption. 7.1.2 Incorrect Dip-stick An incorrect dip-stick may result in the engine being overfilled with oil. This might result in high oil consumption. 7.2 Misassembled Power Cylinder Parts 7.2.1 Piston Rings Make sure
43、that all the rings have been installed with the proper side up. An asymmetric ring that is installed upside down will scrape oil upward causing high oil consumption. 7.2.2 Broken Parts Check all the piston rings for breakage. Piston rings may have been broken during operation or during assembly. Rin
44、gs that were broken on assembly can often be identified by damage to the piston. The broken ends of the rings become polished against the cylinder bore and / or against each other during running if they were broken at assembly or during running. If they were broken during or after tear-down, the bro
45、ken ends are not polished. SAE INTERNATIONAL J2795 Revised AUG2014 Page 7 of 21 Broken ring lands on the piston would also be a cause of high oil consumption and blow-by. It may be necessary to remove the rings to determine whether any ring lands are cracked or broken. Look for cracks on the cylinde
46、r head and also for damage on the head gasket. 7.2.3 Abnormal Marks Check the pistons and rings for abnormal markings. This could be an indication of assembly damage. FIGURE 1 - EXAMPLE OF DAMAGED TO THE THIRD LAND DUE TO INSTALLATION DAMAGE 7.2.4 Improperly Handled Rings A piston ring that is overe
47、xtended or excessively twisted during installation might break in operation or show abnormal marks on the face of the ring. 8. OIL CONSUMPTION AS A RESULT OF A FAILURE High oil consumption will be caused by failure of components. This must be determined when investigating the cause of high oil consu
48、mption. In the subsequent sections there are a few examples of failures that may result in high oil consumption.8.1 Broken Rings A broken piston ring can be easily be found and can result in high oil consumption and high blow-by. SAE INTERNATIONAL J2795 Revised AUG2014 Page 8 of 21 FIGURE 2 - EXAMPLE OF BR
