VALVE AS-CHECK 5274112 - Caterpillar

Probable Causes
Codes
Detonation sensor torque
Air/Fuel ratio
NOx sensor calibration
Valve lash
Excessive deposits
Cylinder misfireOnce, the associated codes have been identified and addressed, if the detonation occurrences continue, use the following steps to conduct mechanical and performance-based checks to help determine the root cause. Some steps may or may not be necessary depending on various factors. For example, an engine with very low hours will unlikely have deposit build up in the cylinder versus high hour engines or engines running on utility fuel supplies will have less likely fuel quality problems as field gas applications. Use site-specific performance data sheet, Gas Engine Rating Pro (GERP), and operating characteristics to help narrow the list of possibilities.Note: The situation is unlikely to have a failed detonation sensor if a detonation event is only being detected at one cylinder of the two cylinders a single detonation sensor monitors. A false detonation event due to a failed sensor would affect both cylinders being monitored by that sensor.Recommended Actions
Table 3
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Look for active or logged codes that are associated with detonation. Refer to the codes associated with detonation section.
C. Verify which cylinders are reporting detonation.
Codes
Result: An associated code is active or logged.
Repair: Troubleshoot any associated codes before continuing with this test.
Result:There are no logged or active associated codes. There are multiple cylinders reporting detonation
Proceed to Test Step 2.
Result:There are no logged or active associated codes. There is a single cylinder reporting detonation.
Proceed to Test Step 6.
2. Interview the operator
A. Determine the type of operation and conditions
B. Determine if any recent changes to the engine or supporting systems have been made.
Ask the following:
- What time of day does detonation occur?
- What loads are applied when detonation occurs?
- Has there been any changes to fuel supplies?
Operation
Result: There are specific times, transient loads, or conditions that may have contributed to detonation after discussion with the operator.
Repair: Determine the best method for site-specific maintenance or operational training to help minimize system changes or fluctuations in fuel quality, load, or operation.
Result: No unusual or abnormal activity was found. Engine is under normal, stable operating conditions.
Proceed to Test Step 3.
3. Check Detonation Sensor Torque
A. Check for proper torque of the detonation sensor.
Proper torque is 15 3 N m (11 2 lb ft)
Torque
Result: The sensor torque value is OK.
Proceed to Test Step 4.
Result: The sensor torque value is NOT OK.
Repair: Torque the sensor to the proper torque value.
If the problem is not resolved, proceed to Test Step 4
4. Swap Detonation Sensors
A. Turn the battery disconnect switch to the OFF position.
B. Swap the suspect detonation sensor with another detonation sensor on the engine.
Note: Attempt to swap the sensor with one that is on the opposite bank or furthest away from the suspect sensor mounting location.
Note: Ensure that the sensors are properly torqued after the swap.
C. Turn the battery disconnect switch to the ON position.
D. Start the engine and run the engine at normal operating conditions if possible.
Sensor
Result: