Cummins/Onan GTA14 Engine

⚠ Make sure timing light voltage matches battery source or the timing light will be damaged

Tools: Low and high-tension timing light

1. Connect timing light induction pick-up clamp around #1 cylinder spark plug secondary wire.
2. Connect red power lead to battery positive and black lead to negative.
3. Point timing light toward back side of accessory drive pulley to read degrees BTDC.
4. Loosen the two ignition generator mounting cap-screws to adjust timing.
5. Rotate ignition generator clockwise to advance or counter-clockwise to retard.
6. Tighten the two mounting cap-screws.

⚠ Do not adjust belt tension to full value with the adjusting screw

Tools: Belt tension gauge

1. Loosen lock nut securing idler pulley to water pump.
2. Turn adjusting screw to adjust v-ribbed belt tension to 623 N (140 lb.).
3. Rotate crankshaft one revolution to allow belt to stretch and recheck tension.
4. Secure idler pulley by tightening the lock nut.

1. Check carburetor throttle idle position against throttle stop pin; adjust linkage length until screw rests against stop pin.
2. Manually lift governor lever through full throttle range and check for linkage bind.
3. Start engine and adjust low-speed stop screw on governor head for desired idling speed.

⚠ Do not pull or pry on the fan to rotate the engine

Tools: Feeler gauges, Inch pound torque wrench Part No. 3376592, Torque wrench adapter Part No. ST-669

1. Disconnect battery and remove rocker housing covers.
2. Tighten rocker lever shaft cap-screws.
3. Tighten rocker lever housing cap-screws in sequence 1 through 6, then 7 and 8.
4. Rotate accessory drive nut clockwise to align 1-6 VS mark with pointer.
5. Confirm both valves closed on cylinder No. 1.
6. Loosen lock nuts on intake and exhaust adjusting screws.
7. Insert correct feeler gauge between crosshead top and rocker lever pad.
8. Tighten adjusting screw (torque wrench or feel method) and hold while tightening lock nut.
9. Recheck feeler gauge drag; adjust all valves in firing order 1-5-3-6-2-4.
10. Install rocker lever covers.

⚠ Verify batteries have full charge before starting

Tools: Compression gauge, Spark plug removal tool

1. Shut off gas fuel valve and tag DO NOT OPEN.
2. Ground the ignition G lead to prevent ignition spark.
3. Remove spark plug probes and check for oil or water contamination.
4. Remove spark plugs from all cylinders.
5. Block engine throttle wide open.
6. Install compression gauge in #1 cylinder.
7. Crank engine until 6 to 8 revolutions and gauge reading is stable.
8. Record reading in psi.
9. Release gauge pressure and remove gauge.
10. Repeat for each cylinder.

Tools: Ohmmeter

1. Turn engine off and disconnect batteries.
2. Visually check coil for cracks, carbon tracking and physical damage.
3. Disconnect wiring to the coil.
4. Connect ohmmeter to positive and negative terminals and read primary resistance.
5. Connect ohmmeter to coil positive terminal and high-tension terminal and read secondary resistance.
6. Reconnect all wiring and batteries.

⚠ Never operate the engine without an air cleaner

1. For turbocharged engines operate at rated RPM and full load.
2. Check air cleaner service indicator or gauge.
3. Change filter element when red indicator flag is raised.
4. Reset button in end of service indicator after servicing.

⚠ Do not remove radiator cap from a hot engine

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

1. Turn coolant filter head shut-off valve to Off position.
2. Remove and discard coolant filter; clean gasket surface on filter head.
3. Apply light film of Lubriplate 105 to coolant filter gasket sealing surface.
4. Install filter as specified by manufacturer.
5. Open shut-off valve and install coolant system pressure cap.
6. Operate engine until coolant temperature is above 82 C [180 F] and check for leaks.
7. Check coolant level after air is purged.

⚠ Never use water alone for coolant

⚠ Wait until coolant temperature is below 50 C [120 F] before removing pressure cap

1. Fill system with 50 percent water and 50 percent ethylene glycol antifreeze mixture.
2. Do not exceed maximum fill rate of 14 liters/min [8.5 U.S. Gal./min.].
3. Install pressure cap and operate engine until it reaches 80 C [176 F].
4. Check coolant level again.

⚠ Do not install the radiator cap during flushing

⚠ Do not use caustic cleaners; aluminum components will be damaged

1. Fill system with mixture of sodium carbonate and water (0.5 kg per 23 liters).
2. Operate engine 5 minutes with coolant temperature above 80 C [176 F].
3. Shut engine off and drain cooling system.
4. Fill cooling system with clean water.
5. Operate engine 5 minutes above 80 C [176 F] and drain.
6. Repeat flush until water drained is clean.

⚠ Replace belts as a complete set when a drive uses two or more belts

Tools: Belt tension gauge

1. Loosen adjusting mechanism and move pulley centers close together.
2. Install belts without excessive force; do not roll or pry belt on.
3. Select correct gauge and tension per Belt Tension Chart.
4. Check pulley alignment and belt riding depth.

⚠ Hot oil can cause personal injury

⚠ Oil pressure must be indicated within 15 seconds after starting or shut off engine

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

1. Operate engine until water temperature reaches 60 C [140 F]; shut off and remove oil drain plug (17-mm).
2. Clean filter head area, remove filter with 118 to 131 mm filter wrench, clean gasket surface.
3. Install correct oil filter (LF3000).
4. Fill oil filter with clean oil; apply light film of oil to gasket.
5. Install filter; check and clean oil drain plug threads and sealing surface.
6. Install oil drain plug.
7. Fill engine: pan 36.00 L, filter 2.70 L, total system 41.64 L.
8. Operate engine at idle and inspect for leaks.
9. Stop engine, wait 5 minutes, check and top up oil level to H mark.