Cummins/Onan GTA8.3 Engine

⚠ Check or set valves with engine cold below 60°C [140°F].

⚠ Make sure timing pin is disengaged before rotating engine.

Tools: feeler gauge, flathead screwdriver, torque wrench

1. Remove air crossover tube (water-to-air system only).
2. Disconnect support clamps and hose clamps; remove vent tube.
3. Remove valve cover.
4. Locate TDC for cylinder No. 1 using vibration damper marks.
5. Check or set intake clearance 0.30 mm and exhaust clearance 0.61 mm with engine cold.
6. Set valves per sequence with flathead screwdriver.
7. Tighten locknuts to 24 Nm [18 ft-lb] and recheck lash.
8. Rotate engine 360 degrees and adjust remaining valves.
9. Install valve cover and torque to 24 Nm [18 ft-lb].
10. Install crankcase vent tube and air crossover tube.

⚠ Severe engine damage will result if the valve is left in the closed position.

⚠ Never over concentrate cooling system with DCA4.

Tools: filter wrench

1. Turn coolant shutoff valve to OFF position.
2. Remove and discard coolant filter; clean gasket surface.
3. Apply light film of Lubriplate 105 or equivalent to filter gasket.
4. Install filter as specified by manufacturer.
5. Open shutoff valve and install coolant system pressure cap.
6. Operate engine until coolant temperature above 82 °C [180 °F] and check for leaks.
7. After air purged, check coolant level.

⚠ Do not install the radiator cap. The engine is to be operated without the cap for this process.

⚠ Do not use caustic cleaners in the cooling system. Aluminum components will be damaged.

1. Fill the system with a mixture of sodium carbonate and water: use 0.5 kilograms [1.0 lb] of sodium carbonate for every 23 liters [6.0 U.S. Gallons] of water.
2. Do not install the radiator cap; operate the engine for 5 minutes with the coolant temperature above 80 C [176 F].
3. Shut the engine off and drain the cooling system.
4. Fill the cooling system with clean water.
5. Operate the engine for 5 minutes with the coolant temperature above 80 C [176 F].
6. Shut the engine off and drain the cooling system.
7. If the water being drained is still dirty, flush the system again until the water is clean.

⚠ Applying excessive force in the opposite direction of wind-up or after the tensioner has been wound up to the positive stop can cause the tensioner arm to break.

1. Lift the tensioner arm and pulley to remove and install the belt.
2. The belt tensioner winds in the direction that the spring tang is bent over the tensioner body.
3. To loosen the tension on the belt, rotate the tensioner to wind the spring tighter.

⚠ Hot oil can cause personal injury.

⚠ Mechanical overtightening can distort threads or damage filter element seal.

Tools: 17 mm wrench or socket, 118 to 131 mm filter wrench

1. Operate engine until water temperature reaches 60 °C [140 °F] and shut off.
2. Remove oil drain plug and drain oil.
3. Remove filter using filter wrench, clean gasket surface.
4. Install correct oil filter LF3000.
5. Fill oil filter with clean lubricating oil.
6. Apply light film of oil to gasket before installing new filter.
7. Install oil drain plug and torque to 80 Nm [60 ft-lb].
8. Fill engine to proper level.
9. Operate engine at idle and inspect for leaks.

⚠ Do not engage starter motor for more than 30 seconds at a time. Wait for two minutes between each start.

⚠ After the engine has run for several minutes, add lubricating oil to compensate for oil absorbed by the filter element(s) and oil cooler.

1. Fill crankcase to the FULL mark on the dipstick.
2. Crank the engine for 15 seconds with ignition OFF until oil pressure appears on the gauge or warning light goes out.
3. Refill crankcase to the FULL mark on the dipstick.

⚠ Do not engage starter motor for more than 30 seconds at a time.

⚠ Wait for two minutes between each start.

1. Remove turbocharger oil inlet line and pre-lubricate bearing with 50 to 60 cc clean oil.
2. Reconnect oil supply line.
3. Fill crankcase to FULL mark on dipstick.
4. Crank engine for 15 seconds with ignition OFF until oil pressure appears.
5. Refill crankcase to FULL mark.

⚠ Mechanical overtightening can damage spark plug and cylinder head.

⚠ Do not touch porcelain area on spark plug.

Tools: torque wrench, magnetic spark plug socket (Snap-On P.N. S971KA)

1. Install new spark plug in cylinder head with clean porcelain.
2. Use extension and magnetic spark plug socket and thread in by hand.
3. Torque spark plug to 35 to 41 Nm [26 to 30 ft-lb].
4. Apply small amount of dielectric grease inside and outside spark plug boot.
5. Carefully place plug boot onto spark plug terminal and press until snap is felt.

⚠ Be careful not to drop the spark plug.

Tools: 5/8 in deep-well spark plug socket, extension, 3/8 inch hose

1. Disconnect wires from ignition coil end first, then spark plug end.
2. Remove rubber insert from spark plug socket to prevent contamination.
3. Loosen spark plug with 5/8 in deep-well rubber insert spark plug socket.
4. Slip 3/8 inch inside diameter hose over plug end and turn counterclockwise.
5. Lift spark plug out and mark with cylinder number.
6. Visually inspect plug wires, extenders and connections for damage.

⚠ Always know the location of the manual fuel shut-off valve in the event of an emergency or while servicing the engine.

1. Let the engine idle a few minutes before shutting it down; idle 3 to 5 minutes to allow lubricating oil and water to carry heat away.
2. Turn off the fuel-gas with either the automatic or manual shut-off valve and allow the engine to come to a complete stop.
3. Turn ignition switch to OFF position.

⚠ Before starting be sure that everyone is clear of the engine and the equipment.

⚠ Do not crank the engine for more than 30 seconds at a time; wait two minutes before attempting to crank again.

⚠ Continuous operation with low coolant temperature below 60 C [140 F] or high coolant temperature above 100 C [212 F] can damage the engine.

1. Check the lubricating oil and engine coolant levels.
2. Set the throttle for idle speed.
3. Disengage the clutch (if equipped) or open the main circuit breaker on generator set applications.
4. Open the gas supply shut-off valve.
5. If equipped with fuel shutoff valves with manual reset, return manual reset to open position before cranking engine.
6. Push the reset button on the instrument panel.
7. Hold in the safety switch override button or turn timer past 20 seconds and push the start button.
8. Release the override button when oil pressure gauge shows an increase in oil pressure; oil pressure must be indicated within 15 seconds.
9. Engage the clutch, if equipped, and run the engine at just above idle to allow coolant to warm up.
10. Idle the engine no more than 3 to 5 minutes at 1000 RPM before applying the load or until water temperature reaches 60 C (140 F).

⚠ The system must be filled slowly to prevent air locks.

1. Drain the coolant.
2. Remove the supply line connection.
3. Remove the discharge line connection.
4. Remove the aftercooler pump.
5. Clean the sealing surfaces on the cylinder block.
6. Install the aftercooler pump along with a new gasket; torque 77 N.m [57 ft-lb].
7. Connect the supply and discharge lines.
8. Fill the cooling system with a mixture of 50% water and 50% ethylene-glycol type antifreeze.