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Cummins/Onan — 4-1

For these Cummins/Onan models: MCGBA, MCGCA, MCGDA, MCGDB, MCGGA, MDGDA, MDGDB, MDGDC, MDGDD.

Applies to: Cummins Onan Mcgba, Cummins Onan Mcgca, Cummins Onan Mcgda, Cummins Onan Mcgdb, Cummins Onan Mcgga, Cummins Onan Mdgda, Cummins Onan Mdgdb, Cummins Onan Mdgdc, Cummins Onan Mdgdd

Procedure

  1. 4. Troubleshooting The generator set has sensors that continuously monitor the engine for low oil pressure, high engine temperature and high exhaust temperature of a wa- ter cooled exhaust. If an abnormal condition occurs, the fault circuit breaker will trip and the engine shuts down. After the problem is corrected, reset the fault circuit breaker to restart the generator set. Table 4-1 describes the operation of the fault condi- tion system (including optional features) and lists troubleshooting procedures. SAFETY CONSIDERATIONS High voltages are present within the control box and generator output box when the generator is run- ning. Do not open the control box or generator out- put box while the set is running. WARNING Contacting high voltage compo- nents can cause severe personal injury or death. Keep control and output box covers in place during troubleshooting. Generator set installations are normally designed for remote starting. When troubleshooting a set that is shut down, make certain the generator set cannot be accidentally restarted. To prevent accidental starting, always remove the negative battery cable from the set starting battery. CAUTION Always disconnect a battery char- ger from its AC source before disconnecting the battery cables. Otherwise, disconnecting the cables can result in voltage spikes high enough to damage the DC control circuits of the set. WARNING Accidental starting of the generator set while working on it can cause severe per- sonal injury or death. Prevent accidental start- ing by disconnecting the starting battery cables (negative [–] first). Arcing can ignite the explosive hydrogen gas given off by batteries, causing severe personal injury. Arcing can occur if the negative (–) bat- tery cable is connected and a tool being used to connect or disconnect the positive (+) battery cable accidentally touches the frame or other grounded metal part of the set. To prevent arc- ing, always remove the negative (–) cable first, and reconnect it last. When a fault condition occurs during operation, fol- low the procedures in Table 4-1 to locate and cor- rect the problem. For any symptom not listed, con- tact an authorized service center for assistance. Redistribution or publication of this document, by any means, is strictly prohibited. 4-2 TABLE 4-1. TROUBLESHOOTING WARNING Many troubleshooting procedures present hazards that can result in severe personal inju- ry or death. Only qualified service personnel with knowledge of fuels, electricity, and machinery haz- ards should perform service procedures. Review safety precautions on pages ii and iii.. CHECKS AND CORRECTIVE MEASURES 1a. Service the battery and battery terminals and cables. See Maintenance. b. Replace the control circuit fuse (above the flywheel housing in a twist-lock holder) if it has blown. 2a. Check the fuel supply. b. If a fault circuit breaker has tripped, service the fault, and reset the circuit breaker. c. Service the battery if the engine cranks too slowly to start, refill with engine oil of suitable viscosity and plug in or service the engine coolant heater, if provided. Install an engine coolant heater if necessary. See Maintenance. 3a. Shut down the set if possible. See Maintenance for servicing the cooling system. b. Disconnect as many non-critical loads as possible so that the engine will run cooler, and service as soon as possible. 4a. Fill coolant, if necessary, after the engine has cooled down, and fix any leaks. b. See Maintenance for servicing the cooling system. c. Reset the tripped fault circuit breaker. 5a. Clean out the sea water strainer and make sure the sea water cock is fully open. b. Call your distributor to service the water cooled exhaust sys- tem. c. Reset the tripped fault circuit breaker. 6a. Shut down the set if possible. Fill oil, if necessary. b. Disconnect as many non-critical loads as possible so that the engine will run cooler, and service as soon as possible. 7a. Fill oil, if necessary. See Maintenance. b. Call your distributor to service the engine lubrication system. c. Reset the tripped fault circuit breaker. 8a. Check the governor-throttle linkage. See Adjustments. b. Reset the tripped fault circuit breaker. 9a. Determine the cause (overload or short circuit) and clear the fault. b. Reset the line circuit breaker. c. Reset the field circuit breaker. SYMPTOMS
  2. 1. The engine does not crank.
  3. 2. The engine cranks, but does not start.
  4. 3. The engine coolant temperature gauge indicates 220° F or more while the engine is running.
  5. 4. The engine shuts down due to high engine temperature or low coolant level.
  6. 5. The engine shuts down due to high exhaust temperatu

Source: manual:960-0151B Onan MCGBA CA GA DA DB DA DB DC DD Operators Manual (6-2000) .pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.