Introduction The cylinder cutout tests are for the engines that are listed above. The cylinder cutout tests have been added to Version 3.2.1 of the Caterpillar Electronic Technician (ET). This is a special upgrade to the regular Version 3.2 release that was delivered in October 2000. The test is not currently cu rrently able to run on 793 truck engines if the engine is in chassis. Parasitic loads cause the test to abort prematurely. The test may be used if the engine is removed from the truck and the parasitic loads are reduced. The test is useful for troubleshooting low power, rough operation, misfiring, and excessive fuel consumption. The test is designed to provide satisfactory results without externally loading the engine. The test provides a fast method and an effective method in order to diagnose cylinders without the use of a dynamometer. This makes the test well suited for use in the field. Proper use of the tests will reduce troubleshooting time and repair costs. The tests will also improve troubleshooting accurac y. Do not perform any procedure in this Special S pecial Instruction until you read this information and you understand this information.
Test Overview The diagnostic tests compare the performance between the cylinders. The tests can determine if the cylinders have a problem. ET will display an "OK" status or "Not OK" status for each cylinder at the end of the test. There are five tests. One test was added for each of the following engines with standard rotation 3508, 3512, and 3516. One test was added for 3512 and 3516 engines with reverse rotation. The 3508 engine with reverse rotation uses the same test as the 3508 engine with standard rotation.
Description of the Test The firing order is divided and the cylinders c ylinders are put into cylinder groups. There are two cylinder groups for the 8 cylinder engine. The test for the 12 and 16 cylinder engines contain three cylinder groups. Refer to table 1. The tests for each engine configuration are slightly different. All of the tests work in the 789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(SE..B.Página 2 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 same general manner.
The test sets desired engine speed to 1200 rpm or to the rated speed if the rated speed is below 1200 rpm. One cylinder group is selected and the test cuts out the remaining c ylinders. Next, the test cuts out each of the cylinders in the selected group by cutting out one cylinder at a time. Injection duration is then used to compare the performance of each cylinder to the other cylinders. When one group is finished the test advances to the next group until all cylinders have been tested. After all cylinders have been tested, the entire test runs a gain and the results are averaged. After the completion of both test cycles an "OK" or a "Not OK" status is given for each cylinder. This method of testing has several advantages. The multiple cylinder cutout test cuts out the majority of the cylinders by loading the engine internally. This eliminates the need to externally load the engine. Accurate testing of the engine can be completed with the engine in the chassis and on the site. In addition, when the engine is running on only a few cylinders it is possible to measure the performance of each cylinder with greater resolution. Cylinders were placed into cylinder groups in a manner that provides uniform spacing in the firing order. This allows the engine to run as smoothl y as possible on only a few cylinders. Perfect spacing between the firing of the cylinders is not possible for all of the engine configurations. The specific cylinders in each group of each test are shown in table 1. The 3508 engine with standard rotation or reverse rotation allows the use of the same cylinder cutout test. The 12 and 16 c ylinder engines require different tests for standard rotation or reverse rotation. ET will automatically detect the engine configuration. ET will then select the proper test for the engine configuration. The first cylinder group on 16 cylinder engines contains 6 cylinders and the other two groups contain 5 cylinders. The first cylinder group has lower numbers for the injection duration since the group has an extra cylinder. The cylinder-to-cylinder variation is calculated only within a cylinder group and the "OK" and the "Not OK" status will still be correct. Table 1 Engine Configuration Cylinder Cutout Test Cylinder Groups 3508 Standard and Reverse Rotation 5 Cylinder 1-4-6-7, 2-3-5-8
3512 Standard Rotation 9 Cylinder 1-4-10-11, 2-5-7-12, 3-6-8-9 3512 Reverse Rotation 9 Cylinder 1-6-8-11, 4-5-7-10, 2-3-9-12 3516 Standard Rotation 12 Cylinder 1-6-8-9-13-16, 2-3-10-11-14, 4-5-712-15 3516 Reverse Rotation 12 Cylinder 1-2-4-9-12-13, 3-6-8-11-16, 5-7-1014-15 789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(SE..B.Página 3 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004
General Test Requirements 1. The engine must maintain engine speed of 1200 rpm or the rated speed if the rated speed is below 1200 rpm within ± 125 rpm. An extremely rough running engine will need to be diagnosed by using other methods such as the manual single cylinder cutout test. 2. The engine coolant temperature must reach 68 °C (154 °F) to prevent cold mode and other characteristics of a cold engine from affecting the test results. If the engine will not warm up, the coolant temperature regulators may need to be replaced before the test is run. 3. No load should be placed on the engine. The test was designed in order to provide an effective means of troubleshooting the engine without a dynamometer. Since the test cuts out the majority of the cylinders the engine will not be able to carry much of an external load. Common parasitic loads are acceptable and the loads will not affect the test unless the loads change during the test. Higher loads will cause the test to abort if the engine is unable to maintain engine speed within the allowable test speed. In addition, higher loads ma y cause torsional damage to engine components.
Beginning the Test ET will set desired engine speed to 1200 rpm or to the rated speed if the rated speed is below 1200 rpm. ET will override the inputs of the throttle position sensor or other speed control devices in order to set the engine speed. Ensure that running the engine at the test speed without throttle control will not have an y adverse effects. Transmissions should be placed in Neutral. Vehicles should be placed in Park. Parking brakes should be applied. Generators should be off-line. Note: Prematurely stopping the test or disconnecting ET du ring the test will return engine speed control
to normal operation after a delay of several seconds. The engine speed may be low idle, rated speed, or any other speed, depending on the position of the throttle sensor or other speed con trol devices. Refer to ""Additional Information" " before using this test on engines that are used in the following applications: 789 Off Highway Trucks 1500 rpm and 1800 rpm Generator Set Engines Machine engines that are installed on a dynamometer. When the engine and related equipment is ready for testing begin the test. 1. Connect ET to the electronic control module. 2. Start the engine. Run the engine until the engine coolant temperature is at the normal operating temperature. 789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(SE..B.Página 4 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 3. Pull down the "Diagnostics" menu. Select "Diagnostic Tests" and then select "Cylinder Cutout Test". Refer to illustration 1. 4. ET will display the screen for the manual cylinder cutout test that is shown in illustration 2. Select the "Start" button at the bottom of the screen in order to proceed to the multiple cylinder cutout test. 5. After selecting the "Start" button, ET will display a screen that lists the required test conditions. Select the "Continue" button at the bottom of the screen if the conditions have been met. Illustration 1 g00775975 Illustration 2 g00769597
789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(SE..B.Página 5 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 6. ET will display a "Warning" dialog box. Read the warning and select "OK" if you are ready to continue. 7. The engine should now go to 1200 rpm or to the rated speed if the rated speed is below 1200 rpm and ET will begin the cylinder cutout test. 8. The test runs two complete cycles and the results are averaged for consistency. Five minutes are required in order to complete the test for the 8 cylinder engine. Eleven minutes are required in
order to complete the test for the 16 cylinder engine. If the test is completed successfully ET will display "Test Complete!" dialog box. Select "OK" in order to proceed to the test results. 9. ET will now display the "c ylinder status" for each cylinder as "OK" or "Not OK". 10. Select the "Show Details" button in order to view the additional details of the test. 11. Print test results or save test results by selecting the "Print" button in the lower right hand corner of the screen.
Using Test Results It is important to understand that this test evaluates the performance of the entire cylinder. The results of the test will not isolate a problem to the specific c omponents that are within a c ylinder. The following steps are recommended in order to repair a cylinder for a test result of "Not OK". 1. Check the following items: bridge adjustments, valve adjustments, the h eight of fuel injector timing, the part number of the fuel injector, the wiring harness for the fuel injector and electrical connections. Wear of valve train components can cause valve lash adjustments and height adjustments for the fuel injector timing to be out of specification. Adjustments that are out of specification will cause a cylinder to be reported as "Not OK". New fuel injectors have a trim code that is printed on the top of the injector tappet. The trim code is four digits. The trim code must be programmed into the ET calibration screen. Earlier fuel injectors t hat do not have trim codes should be programmed to the default value of 1100. If any of the items are out of specification, repair the condition and rerun the cylinder cutout test in order to confirm the repair. If the status of the cylinder is still "Not OK" then p roceed to the next step. 2. Temporarily replace the fuel injector or exchan ge the fuel injector with a fuel injector in a cylinder that tested "OK". 3. Rerun the cylinder cutout test. If a fuel injector was exchanged from ano ther cylinder and the problem follows the fuel injector, replace the fuel injector. If the problem stays with the cylinder, the fuel injector was not the cause of the problem. If the new fuel injector resolved the problem the repair is complete. 4. If the status of the cylinder is still "Not OK" the new fuel injector did not resolve the problem. Do not replace the fuel injector. Proceed to the next step. 5. Continue troubleshooting the other cylinder compon ents such as pistons, valves, and rings. Use
the techniques that exist in order to troubleshoot the problem. Note: When fuel injectors are replaced, include the printed copies of the cylinder cutout tests with any 789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(SE..B.Página 6 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 fuel injectors that are returned to the factory. There should be three cylinder cutout tests if adjustments for the top end were required for the repair. The first test is an initial test. The second is a test after the adjustments to the top end are made. The third test is run after the replacement of a fuel injector in order to confirm the repair. If multiple fuel injectors are replaced, mark the fuel injectors with the appropriate cylinder number. These steps help ensure a successful repair. The steps also help the factory correlate test results with test results from the failure analysis that is performed at the factory.
Interpreting Test Results The test returns an "OK" or "Not OK" indic ation for each cylinder. The results are selfexplanatory and the results are easily interpreted. The test also provides numbers that are for injection duration. The numbers for the injection duration are not easily interpreted. The numbers for the injection duration are provided at the completion of the test by selecting the "Show Details" button. The numbers for the injection duration are not normally required in order to perform a repair. A technician with a thorough understanding of the operation of the test would use the numbers for the injection duration. The information that is listed in table 2 is an example of an engine repair. The information contains results of a cylinder cutout test. The information also contains interpretations of the numbers for the injection duration. The test that is shown in table 2 was run with a faulty injector. The fuel injector in cylinder 7 has a low rate of fuel delivery (28 percent). The test co rrectly identified cylinder 7 as "Not OK". However, the numbers for the injection duration may lead to a different diagnosis. For example, cylinder 5 is the weakest cylinder in the column "Cycle 2" at 1565.54. The test identified cylinder 7 as the weakest cylinder. However, cylinder 5 has the lowest duration number. In order to understand the test results that are listed in table 2, you must remember that the 8 cylinder
cutout test has two cylinder groups. Only the cylinders that are within a test group are compared to each other. The first group contains cylinders 1, 4, 6, and 7. The second group contains cylinders 2, 3, 5, and Table 2 Test Before Repair Cylinder Cycle 1 Cycle 2 Status 1 1653.37 1653.41 "OK" 2 1610.66 1598.56 "OK" 3 1600.46 1590.95 "OK" 4 1661.03 1651.35 "OK" 5 1569.08 1565.54 "OK" 6 1653.15 1641.71 "OK" 7 1589.64 1583.97 "Not OK" 8 1587.90 1592.06 "OK" 789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(SE..B.Página 7 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 8. Compare the results of cylinder 7 with the results that are from cylinders 1, 4, and 6. Cylinder 7 is much lower than the other cylinders in this group. Therefore, ET determined that cylinder 7 was "Not OK". The injection duration of cylinder 5 is slightly lower than the injection duration of cylinder 7. However, cylinder 7 is in a different group so a comparison of these two cylinders is not valid. Cylinder 5 is fairly close to the other cylinders in number 5 cylinder's own group. This is the reason that cylinder 5 tested "OK". Notice that the injection duration for cylinders 1, 4, and 6 is high when the injection duration is compared to the other cylinders. Cylinders 1, 4, and 6 must work harder in order to compensate for cylinder 7. Cylinders 2, 3, 5, and 8 are not affected because the cylinders are in a different cylinder group and the group is not tested with cylinder 7. The next test was run on the same engine after replacing the weak fuel injector in cylinder 7. The results are shown in table 3. After the repair of cylinder 7, ET will now indicat e the status of the cylinders as "OK". Cylinders 1, 4, and 6 are not working hard in order to compensate for cylinder 7. This caused the numbers for the injection duration for 1, 4, and 6 to decrease from the initial test. Cylinder 5 has the lowest number, but cylinder 5 is close enough to the other cylinders that are in the
group in order to test "OK". When all of the cylinders test "OK", do not attempt to make observations about cylinder performance based on the minor variations in the numbers of injection duration. These minor differences are beyond the capabilities of the test. These minor differences are so small that the differences are insignificant. Therefore, do not assume that cylinder 5 is more powerful or less powerful than any of the other cylinders.
Testing Tips Table 3 Test After Repair Cylinder Cycle 1 Cycle 2 Status 1 1576.59 1573.18 "OK" 2 1590.13 1594.12 "OK" 3 1578.82 1573.88 "OK" 4 1579.76 1578.88 "OK" 5 1562.71 1558.12 "OK" 6 1572.12 1559.18 "OK" 7 1576.25 1570.00 "OK" 8 1576.50 1574.00 "OK" 789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(SE..B.Página 8 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 Use the following tips in order to improve the acc uracy of the results of the cylinder test. 1. Run the test when the engine is at normal operating temperature. The test will run when coolant temperature is at least 68 °C (154 °F), but the results will be more consistent and accurate at normal operating temperature. If the engine will not warm up the coolant temperature regulators may be leaking excessively. 2. If the test produces results that are questionable for some reason, rerun the test. Test results are generally consistent and repeatable. There is a small amount of variation from one test to another test. A marginal cylinder may test "OK" one test an d "Not OK" for another test. If test results differ the test that was conducted closest to the no rmal operating temperature is most accurate. 3. Valid test results can not be obtained when accessories are cycling on and off during the test. Turn off the air conditioner. Make sure that other a ccessories such as cooling fans, air compressors, and power steering pumps are always on or always off and do not cycle during the test.
4. The test does not measure the power that is produced by the cylinders. The test only measures the percent of variance between cylinders in the same cylinder group. 5. The test indicates "Not OK" when the cylinder performance is weak. The weak cylinder is compared to the other cylinders that are in the same cylinder group. The test will indicate "Not OK" for a cylinder that is approximately 10 percent to 15 percent low on power. 6. Many customers may not notice a performance problem when only one cylinder is 10 percent to 15 percent low on power. This is especially true on engines with a large number of cylinders. Some applications are more sensitive to small drops in power. 7. Replacing a marginal fuel injector that tests "Not OK" may not always be in the customer's best interest. An example might be on an engine that has no performance complaint and the engine is near a scheduled maintenance interval. Use common sense. 8. The test does not currently detect high power cylinders. A "Not OK" indication is given only for low power cylinders. 9. ET will only compare the cylinders that are in the same cylinder group i n order to determine whether a cylinder is "OK" or "Not OK". C ylinders in one cylinder group can not be compared to cylinders in a different cylinder group. This is especially true on the 16 cylinder test. The three cylinder groups do not contain the same number of cylinders. This results in a difference in the numbers of the injection duration for the first group when the numbers are compared to the other two groups. This situation does not affect the test results. 10. The test checks for cylinder-to-cylinder variation, but the test does not measure the actual power. It is possible that an engine could have an entire set of fuel injectors that are uniformly low on power and test "OK". Although this is possible, it is unlikely. Typically in a worn set of fuel injectors or a damaged set of fuel injectors, some fuel injectors will have more degradation than other fuel injectors. This will cause an increase in the variance. The test should be able to find the variance. 11. An extremely weak cylinder may obscure a weak cylinder that is in the same cylinder group. If this happens, the test will find the extremely weak cylinder first. Then when that cylinder is
789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(SE..B.Página 9 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 repaired and the test is rerun, the repaired c ylinder will test "OK", but a different cylinder in the same group may then test "Not OK". If another cylinder tests "Not OK" after a repair, verify that the cylinder is in the cylinder group that was repaired. If the cylinder is in the same group, then the cylinder was probably weak and the cylinder was obscured by another weak cylinder. If the cylinder is in a different cylinder group, there has been a change. This could be the result of a marginal cylinder, a change in coolant temperature from one test to the next, accessory load cycling, or other factors. 12. The results of the cylinder cutout test are used to supplement the processes of troubleshooting and service. The cylinder cutout test is used with other tests and other procedures in order to guide a technician to a fast, accurate repair.
Additional Information Additional Test Procedures for 789 Off Highway Trucks The steering pump will recharge the accumulators after every 30 to 40 seconds. This is due to the thermal bleed that is internal to the steering valve. The thermal bleed circulates warm oil through the valves in order to prevent thermal shock. The charging of the accumulators creates a load change that affects the cylinder cutout test. The Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand. Personal injury or death can result from improperly checking for a leak. Always use a board or cardboard when checking for a leak. Escaping air or fluid under pressure, even a pin-hole size leak, can penetrate body tissue causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.
789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(.S..EPágina 10 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 following procedure will keep the steering pump on in order to prevent a load change. 1. Locate accumulator charging valve (1) . Illustration 3 g00773479 (1) Accumulator charging valve (2) Drain line (3) Elbow
NOTICE Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop 789B Off-HighwayTruck 7EK00001-UP (MACHINE) POWERED BY 3516 Engine(.S..EPágina 11 de 12 https://sis.cat.com/sisweb/servlet/cat.dcs.sis.controller.techdoc.CSSISFormatTechDocForP. .r.i 09/30/2004 2. Disconnect drain line (2) from elbow (3) that is installed in the accumulator charging valve. 3. Use 6V-9508 Face Seal Plug and 6V-8397 O-Ring Seal in order to plug the drain line that is disconnected from the accumulator charging valve. 4. Use 6V-9829 Cap As in order to cap the elbow. 5. Perform the cylinder cutout test. 6. After the cylinder cutout test, reconnect the drain line to the accumulator charging valve. Note: If the warning light for the Steering Oil Temperature activates, stop the cylinder cutout test and reconnect the drain line. Allow the steering oil temperature to return to normal temperature before you attempt to rerun the cylinder cutout test.
Additional Test Procedures for 1500 rpm and 1800 rpm Generator Set Engines The operation of a 1500 rpm generator or 1800 rpm generator at the 1200 rpm test speed may cause some voltage regulators to deactivate during the test. This may cause a change in the engine load which will make the cylinder test invalid. If the voltage regulator dea ctivates during the test, stop the test. Run the test again while the voltage regulator is off. When all testing is complete reactivate the voltage regulator.
Additional Test Procedures for Running Machine Engines on a Dynamometer
Diagnostic codes are frequently activated when an engine is removed from a machine for dyno testing. These diagnostic codes may prevent the cylinder cutout test from starting. Some machine engines are equipped with an ET Dyno Mode. This feature causes certain diagnostic codes to be ignored. This allows the dyno test to be run on the engine. If this feature is available, put the engine into dyno mode first and then begin the cylinder cutout test. Refer to the Service Magazine 13 November, "Operational Requirements Needed to Use Dyno Mode Tool in Caterpillar Electronic Technician" for more information about ET dyno mode. Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. Copyright 1993, 2004 Caterpillar Inc. All Rights Reserved. Private Network For SIS Licensees. Thu Sep 30 09:48:11 UTC-0400 2004
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