Useful Tips to Start Cummins Engines

Useful Tips to Start Cummins Engines

Without question, it is very necessary and important to learn how to correctly start diesel engines. If you don’t know, then take a few time to read this article and you will know what you should pay attention to when starting the engines

Staring the Engines

Please note that starting requires that clean air and fuel are supplied to the combustion chambers in the proper quantities at the correct time.

Normal Starting Procedure

Warning: Before starting, be sure that everyone is clear of the engine and equipment.

If the fuel system is equipped with an overspeed stop, push the “Reset” button before attempting to start the engine.

1. On engines equipped with an air activated prelube device, open the air valve to activate the piston in the prelube device which will lubricate all moving parts in the engine.

Note: On engines equipped with an oil pressure safety switch, hold the fuel by-pass switch in the “start” position until the engine oil pressure reaches 7 to 10 psi (48 to 69 kpa); then, move it to the “run” position.

2. Set the throttle for idle speed and disengage the driven unit.

Caution: To protect the turbocharger during start-up by not opening the throttle or accelerating above 1000 rpm until the idle speed oil pressure registers on the gauge.

3. Open the manual fuel shut-down valve, if equipped. See Fig.3. Electric shut-down valves operate as the switch is turned on. A manual override knob provided  on the forward end of the electric shut-down valve allows the valve to be opened in case of an electric power failure. To use, turn fully clockwise; return it to the run position after an electric repair.

Warning: Check before starting Cummins engines, make sure everyone leaves the engine and equipment to prevent an accident.

4. Pull the decompression release lever (if equipped) and press the starter button or turn the key switch to the “start” position. After three or four seconds of cranking, close the decompress release lever and continue to crank until the engine fires.

Caution: To prevent permanent cranking motor damage, do not crank the engine for more than 30 seconds continuously. If the engine does not fire within the first 30 seconds, wait one to two minutes before recranking.

5. At the initial start or after oil or filter changes and after the engine has run for a few minutes, shut it down and wait 15 minutes for  the oil to drain back into the pan. Check the engine oil level again; add oil as necessary to bring the oil level to the “H” mark on dipstick. The drop in oil level is due to absorption by the oil filters. Never operate the engine with the oil level below the low level mark or above the high level mark.

If you find that your diesel generator is hard to start, then here are the reason for why.

    Battery failure

    The single most frequent service call for generator failure is related to battery failure. Eighty percent of all battery failure is related to sulfation buildup — the accumulation of lead sulfates on the plates of lead-acid batteries. This buildup occurs when the sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to coat the battery's lead plates. When enough plate area has sulfated, the battery will not be able to provide enough current and will normally need to be replaced. Battery failure is commonly the result of low electrolyte levels — battery plates exposed to air will immediately sulfate.

    Battery cells are shorted when sedimentary trays fill up with lead debris. You can avoid shorted batteries if you replace them regularly. Some experts recommend replacing them every three years.

    Although battery failure can result from open cells, this is not a common occurrence. Open cells are the result of an overcurrent of the battery system. If a generator system has had several battery failures determined to be caused by open cells, the unit may require larger batteries capable of higher cold cranking amps (CCAs).

    Frequently, battery failure is due to the charger breaker being open or tripped — often the result of human error rather than actual charger failure. This usually occurs after service on a generator, or some type of maintenance, where the charger has been turned off and not turned back on again when the service is completed. Always double check a generator system after any service or maintenance to make sure everything is functioning properly.

    Because many battery problems are caused by dirty and loose connections, maintenance is critical. Cable connections need to be regularly cleaned and tightened. Battery charger failures are difficult to prevent, and cannot be accurately predicted. However, monitoring the charge rates from month to month will establish a trend that can help map the potential for failure. A properly functioning battery charger will have a constant charge rate for any given system. An increase of amperage may show signs of a battery or charger malfunction.

    Low coolant levels

    The most obvious cause for a low coolant level is either an external or internal leak. Pay close attention to any visible puddles of coolant during weekly inspections of the unit(s). The color of the coolant varies by manufacturer and may look like red-dyed diesel fuel. Inspect oil for any signs of color change or a milky texture and hoses for “crusties” — the sign of coolant seeping and additives drying up at the connection. While many generators are equipped with low coolant level alarms, few have a dedicated alarm indicator for low coolant. Commonly, this alarm will be tied in to a high coolant temp shutdown circuit.

    Internally plugged radiator cores will also cause low coolant level shutdowns. When the generator is under load, the thermostats open completely, and the radiator cannot allow the proper amount of flow through the core. The coolant has to go somewhere, so it purges through the overflow line. As the engine cools off and the thermostat closes, the level drops and activates the low coolant level shutdown.

    This also occurs when float switch-type coolant level sensors are used, and the lines are plumbed to the top and bottom radiator tanks. When the thermostats open, the path of least resistance is through the float switch lines, and the flow causes the float to drop and shutdown the engine. The thermostat will not open enough to cause this during regular weekly running of the generator. It will have to be tested under load to cause the thermostats to fully open. A full load test with an external load bank is the only accurate way to check a cooling system.

    Low coolant temp alarms

    Low coolant temp alarms are mainly the result of faulty block heaters. Given the fact that they run 24 hours a day, seven days a week, they're going to fail periodically. A block heater will normally not cause the engine not to run. You may need to allow a generator to run for a few minutes at no load after startup so that the temperature comes up.

    Why have block heaters? A common misconception is that the engine does not need a block heater in warmer climates. However, a block heater does more than help the engine to start in cold weather. Due to the dissimilar metals that the engines are built with, accelerated wear can occur during startup. The pistons, normally made of aluminum, will expand at a faster rate than the iron cylinder liners. This rapid expansion of the pistons can lead to scuffing of the piston skirt. Block heaters relieve most of this scuffing by maintaining the cooling system temperature and keeping the cylinder liners expanded.

    The extreme temperature inside the block heater is what causes the coolant to circulate through the system. (At times, you can hear the coolant boiling inside of the block heater.) The block heater's high temperatures flash off the coolant into small amounts of steam, causing the coolant to evaporate in slight amounts. While it takes a long time to show a difference in the coolant level, recording the amount of coolant added to the system will help establish a trend. (The block heater thermostat is located at the cold side of the heater.) If the engine is continuously using coolant with no signs of leakage, you should take oil samples and analyze them before continuing further troubleshooting efforts. If the block heater temperature gets excessively high, premature block heater failure or extreme engine damage may occur. Some generators use a control panel to operate their block heater.

    Normal walk-through inspections should include checking the cylinder head (or engine thermostat housing) for temperature and verifying that the engine or block heater hoses are warm. The temperature setting should be between 90°F and 100°F — never more than 120°F.

    Oil, fuel, or coolant leaks

    Most often, oil leaks are not in fact leaks but the result of “wet stacking” (or “engine slobber”) caused by excessive no-load run time. Diesel engine generators are designed to operate with a load — most effectively in the 70% to 80% range of rated output. When generators operate considerably below the rated output level, the engine can start to over-fuel or “wet stack” and damage the engine.