3116 and 3126 HEUI Truck Engines Starting the Engine
Make a thorough under-the-hood inspection before starting the engine. Look for items such as fuel, oil, or coolant leaks, worn belts, and trash buildup. Remove trash buildup and have repairs made as needed.
Perform required Daily maintenance before starting the engine.
NOTE: There will be an indicator lamp on the dashboard of the vehicle marked AIR INLET HEATER.
To aid cold weather starting and reduce white smoke at start-up, the engine is equipped with an electric air heater grid located at the air inlet elbow. Under the proper conditions, the ECM activates a relay which cycles the Air Inlet Heater on and off.
The Air Inlet Heater system is designed to operate prior to start-up, during cranking, and after the engine has started. If the sum of the coolant temperature and the inlet air temperature is below 25°C (77°F), the ECM allows the heater to stay on for preheating when the ignition key switch is turned to the ON (RUN) position. The indicator lamp on the instrument panel will turn on when the Air Inlet Heater system is functioning. The electric air heater grid, the starting motor solenoid, the ECM, and sensors are part of the engine arrangement.
Start the engine using the following procedure.
1.Engage the parking brake. Place the transmission in NEUTRAL. If the vehicle is equipped with a manual transmission, depress the clutch pedal in order to disengage the flywheel clutch. This reduces transmission drag and prevents movement of the vehicle. Depressing the clutch in cold weather can mean the difference between starting and not starting by reducing battery drain.
The CHECK ENGINE/DIAGNOSTIC lamp will turn ON for five seconds as a system lamp check when the ignition key switch is first turned on. If the lamp fails to turn ON, notify your Caterpillar dealer. If the lamp continues to flash after the engine has started, the ECM has detected an engine system problem. Refer to Engine Diagnostics topic.
2.Turn the ignition key switch to the ON position. The Air Inlet Heater system has a preheat function to improve cold weather starting.
NOTE: The AIR INLET HEATER indicator lamp will turn ON for a minimum of two seconds regardless of the coolant temperature. If the AIR INLET HEATER indicator lamp stays ON for more than two seconds, wait until the indicator lamp turns to OFF (approximately 30 seconds) before attempting to start the engine. If the operator attempts to start the engine before the indicator lamp goes OFF, the ECM will control the Air Inlet Heater for the cranking cycle. Attempting to start the engine before the indicator lamp goes OFF could result in excessive white smoke at start-up.
3.Turn the ignition key switch to the START position in order to crank the engine. The Air Inlet Heater will turn ON if the sum of the coolant temperature and the inlet air temperature is less than 25°C (77°F).
DO NOT PUSH DOWN OR HOLD THE THROTTLE DOWN while cranking the engine. The system will automatically provide the correct amount of fuel to start the engine.
If the engine does not start after 15 to 20 seconds of cranking, release the ignition key switch. If the sum of the coolant temperature and the inlet air temperature is less than 25°C (77°F), the Air Inlet Heater preheat cycle will restart. Turn to the ignition key switch to the OFF position. Allow the starting motor to cool for two minutes. Repeat steps 2 and 3.
4.Release the ignition key switch to the ON (RUN) position immediately after the engine starts. After the engine starts, check to make sure the transmission is still in NEUTRAL and release the clutch pedal (manual transmission). The vehicle may be operated at a light load and speed as soon as the engine oil pressure and air pressure have reached normal levels.
After the engine has started, the Air Inlet Heater may continue to operate in a Continuous mode and/or in an On/Off cycle mode. The Continuous mode can last for a maximum of seven minutes, followed by the On/Off cycle mode. During the On/Off cycle mode, the Air Inlet Heater cycles ON and OFF for ten seconds. The Air Inlet Heater will turn OFF when the sum of the coolant temperature and the air inlet temperature exceeds 35°C (95°F).
If the engine is operated with a low load, the engine will reach normal operating temperature sooner than when the engine is idled with no load. When idling in cold weather, increase the engine speed to approximately 1000 to 1200 rpm in order to warm-up the engine more quickly. Do not race the engine in order to speed the warm-up. Limit unnecessary idle time to ten minutes.
Startability will be improved at temperatures below 0°C (32°F) by the use of an automatic ether injection system and/or use of a jacket water heater. This will help alleviate white smoke and misfire during cold weather start-up. Consult your Caterpillar dealer for other means of improving startability in cold temperatures.
An optional ether starting aid is available for use with the engine. The system injects ether into the air inlet manifold AFTER the air inlet heater. Extensive damage to the engine could occur if ether is directed at the air inlet heater element while the air inlet heater is activated.
If the vehicle is equipped with the ether injection system, crank the engine, depress the ether switch, hold the ether switch for three seconds, and release the ether switch. Additional injections may be necessary to start and/or achieve low idle speed.
Occasional starting difficulty may be caused by a low battery charge, a lack of fuel, or a wiring harness problem.
If the engine fuel system has been run dry, fill the fuel tank and prime the fuel system. Refer to the Priming the Fuel System topic.
If the other problems are suspected, perform the appropriate following procedure in order to start the engine.
1.Turn the ignition key switch to the OFF position. Remove the key and turn all electrical accessories OFF before attaching the cables.
2.Connect one end of the positive (+) cable to the positive (+) terminal of the battery being started. Connect the other of the positive (+) cable to the positive (+) terminal of the power source.
3.Connect one end of the negative (-) cable to the negative (-) terminal of the power source. Connect the other end of the negative (-) cable to the starting motor negative (-) terminal or to the engine block. This prevents potential sparks from igniting combustible gases produced by some batteries.
4.Allow sufficient time to partially charge the battery. The engine will not continue to operate after the engine is started if the battery does not have a partial charge.
5.Start the engine. After the engine starts, disconnect the negative (-) cable from the starting motor negative (-) terminal or from the engine block. Disconnect the other end of the negative (-) cable from the negative (-) terminal of the power source.
6.Disconnect the positive (+) cable from the positive (+) terminal of the battery on the engine that is being started. Disconnect the positive (+) cable from the positive (+) terminal of the power source.
Locate the ECM. Two harness connectors are attached to the ECM. The upper connector is the engine harness and the lower connector is the chassis harness. Check the connectors to be sure that the connectors are secure. Perform a “tug test” on EACH wire in the lower connector.
1.Pull (tug) on each wire with approximately 4.5 kg (10 pounds) of force. The wire should remain in the connector.
2.If a wire feels loose, push the wire back into the connector. Then tug the wire again in order to ensure that the wire is locked into place.
3.Start the engine. If the engine does not start, consult the nearest Caterpillar dealer for assistance.
Categories: 3126 | Tags: Starting the Engine | Leave a comment