20450849 Volvo.Penta Hexagon screw

Probable Causes
Active codes and logged codes
Engine Oil Level
Fuel System
Fuel injectors
Proper Lubrication
Low Compression
Valve train componentsRecommended Actions
Note: When changing engine speeds on the 308E2, the engine creates a noise that can be misinterpreted as a miss. The sound is normal and is due to the machine throttle control which increases in steps and due to a restricted exhaust pipe.Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. Active Codes and Logged Codes
A. Establish communication between Caterpillar Electronic Technician (ET) and the Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Download the "Product Status Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.
Troubleshoot any active codes before continuing with this procedure.
Codes
Result: There are active codes.
Troubleshoot any active codes before continuing with this procedure.
Result: There are no active codes.
Proceed to Test Step 2.
2. Check the Engine Oil Level and Obtain an Oil Sample
A. Check the oil level and obtain an oil sample. If the oil level is high refer to Troubleshooting, Oil Contains Fuel, if fuel is present.
Oil
Result: The engine oil sample shows moitor or action required, then skip to Test Step 5.
Make necessary repairs.
Proceed to Test Step 3.
3. Check the Fuel System
Refer to Systems Operation/Testing and Adjusting, "Fuel System" for additional information.
A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only.
B. Ensure that the vent in the fuel cap is not filled with debris.
C. Inspect the fuel system for external leaks.
D. Check that there is no air in the clear primary fuel filter. Refer to Systems Operation/Testing and Adjusting, Low-Pressure Fuel System - Test.
E. Change the primary fuel filter and the in-line filter for the fuel transfer pump.
F. Check fuel quality. Refer to Testing and Adjusting, Fuel Quality - Test, for the proper procedure. Check the fuel tank for debris or foreign objects which may block the fuel supply.
G. Check for the proper operation of the fuel transfer pump. Replace the pre-filter if excessive contamination or if the maintenance interval is exceeded. Refer to Testing and Adjusting, Low Fuel Pressure System-Test, for test information.
Fuel
Result: The fuel system is OK.
Proceed to Test Step 4.
Result: The fuel system is not OK.
Make necessary repairs.
4. Fuel Injectors
A. If service has been performed on the engine fuel system recently, verify that the injector trim codes in the Engine ECM match the injector for each cylinder. If injectors were moved between cylinders or if an injector was replaced and the injector trim codes were not updated in the Engine ECM, this can cause an engine miss.
B. Access the "Cylinder Cutout Test" in the "Diagnostic Tests" under the "Diagnostics" menu. Cut out each cylinder one at a time to listen for improvements in the engine. If engine sound improves while cutting out a specific cylinder or cylinders, then check that the injector(s) are working properly by using 440-6907 Injector Kit.
Note: The injector deliver quantity is not a reliable indicator of a failed injector. It is not recommended to use that test in determining if an injector is failed.
Fuel Injectors
Result: If injector(s) trim codes for each cylinder do not match what is in the Engine ECM, then refer to Special Instruction, REHS9707, for the procedure to install the new injector QR codes within the Engine ECM and on-line. Confirm that this resolves the issue.
Result: If injector(s) are found to be defective, then replace the injector(s). Refer to Disassembly and Assembly, Electronic Unit Injector - Remove and Install. Refer to Special Instruction, REHS9707, for the procedure to install the new injector QR codes within the Engine ECM and online. Confirm that this resolves the issue.
Note: If two or more injectors are not working properly, this is likely a result of water in the fuel, bad fuel, or contaminated fuel. Contaminated fuel can occur by pre-filling the fuel filter or contamination during a previous repair of the fuel system. The root cause needs to be determined to prevent a repeat occurrence.
Result: There are no previous known services on fuel system and there was no noticeable improvement during the cylinder cut out test. The customer could have ordered injectors through parts and did not change the injector trim codes in the Engine ECM. Visually confirm that the injector trim code for each cylinder matches what is in the Engine ECM. Refer to Special Instruction, REHS9707, for the procedure to install the new injector QR codes within the Engine ECM and online.
5. Low Compression
A. Perform a compression test. Refer to Testing and Adjusting, Compression – Test.
B.Possible causes of low compression:
• Faulty piston
• Faulty piston rings
• Worn cylinder bores
• Worn valves
• Faulty cylinder head
• Damaged cylinder head
Compression
Result: Low compression is not present.
Proceed to Test Step 6.
Result: Low compression is present.
Make the necessary repairs.
6. Valve Train Components
A. Check the valve lash. Refer to Troubleshooting, "Valve Lash Is Excessive".
B. Check for damage to valve train components. Remove the valve cover from the suspect cylinders. Check the following items for damage:
1. Camshaft
2. Valve springs
3. Camshaft followers
4. Rocker shaft
5. Bridges
6. Pushrods
7. Injectors
Refer to the Disassembly and Assembly for additional information.
C. Check for valves that do not move freely. Remove the cylinder head and inspect the valves.
Refer to the Disassembly and Assembly for additional information.
Valve train
Result: The valve train components are not damaged.
Result: The valve train components are damaged.
Make the necessary repairs, Verify that the repair eliminated the problem.
Complete the procedure in the order in which the steps are listed.The procedure corrected the issue. Return the engine to service.