The Cummins/Onan KTA-38-GI is an engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, including the 750 DFZ. It holds 129 L (34.1 gal) of oil and 208 L (54.9 gal) of coolant.
Also known as: Cummins KTA-38-GI
Part of the Cummins/Onan KTA-38 engine family — 3 variants share parts & fitment.
| Oil capacity | 129.0 L |
|---|---|
| Coolant capacity | 208.0 L |
| Rated speed | 1800 rpm |
How to read your Cummins/Onan engine serial & model number →
Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan KTA-38-GI.
| Item | Action | Hours | Months | Notes |
|---|---|---|---|---|
| Crankcase oil (new generator sets) | Drain | 50 hr | First service — Drain and replace the crankcase oil after the first 50 hours of operation on new generator sets | |
| Generator bearing | Inspect | 1000 hr | Have bearing inspected for wear every 1000 hours by an Onan Distributor | |
| Generator bearing (prime power) | Replace | 10000 hr | For prime power, replace at least every 10,000 hours or after two years | |
| Generator bearing (standby power) | Replace | 60 mo | For standby power, replace at least every five years |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Type | Item | Value | Unit | Condition |
|---|---|---|---|---|
| Clearance | Air cleaner nozzle distance from element | 1 | inch | 25 mm minimum |
| Pressure | Air cleaner cleaning air pressure | 30 | psi | 207 kPa; DFW, DFY and DFZ |
| Pressure | Crankcase breather drying air pressure | 30 | psi | maximum (OSHA) |
| Pressure | Low oil pressure shutdown setpoint | 14 | psi | 97 kPa; time delayed about 10 seconds following starter disconnect |
| Pressure | Normal engine oil pressure range | 50 to 70 | psi | 345 to 483 kPa |
| Pressure | Pre-low oil pressure alarm (optional 12-lamp system) | 20 | psi | 137 kPa or less |
| Pressure | Radiator air discharge static pressure | 0.25 | inch H2O | 0.018 inch Hg; 450 DM, 500 DM, 600 DFY, 750 DFZ |
| Pressure | Radiator air discharge static pressure | 0.5 | inch H2O | 0.037 inch Hg; 450 DFW |
| Resistance | Battery specific gravity (recharge below) | 1.260 | specific gravity | use a hydrometer |
| Speed | Cycle cranking option | 15 | seconds | three 15-second cranking cycles with two 15-second rest periods |
| Speed | Fine speed adjustment range (SPEED ADJUST potentiometer) | ±100 | RPM | less than |
| Speed | Frequency meter speed relation | 30 | r/min | each hertz equals 30 r/min |
| Speed | No-load governed speed, 50 Hz 3% droop | 1545 | RPM | 51.5 Hz |
| Speed | No-load governed speed, 50 Hz 5% droop | 1575 | RPM | 52.5 Hz |
| Speed | No-load governed speed, 50 Hz isochronous | 1500 | RPM | 50.0 Hz |
| Speed | No-load governed speed, 60 Hz 3% droop | 1854 | RPM | 61.8 Hz |
| Speed | No-load governed speed, 60 Hz 5% droop | 1890 | RPM | 63.0 Hz |
| Speed | No-load governed speed, 60 Hz isochronous | 1800 | RPM | 60.0 Hz |
| Speed | Overcrank cranking limit (standard control) | 75 | seconds | starter disengages after 75 seconds of cranking |
| Speed | Overspeed shutdown, 50 Hz units | 1850 ± 50 | r/min | |
| Speed | Overspeed shutdown, 60 Hz units | 2100 ± 90 | r/min | |
| Speed | Starter disconnect speed | 450 to 570 | r/min | |
| Temperature | High engine temperature shutdown | 215 | °F | 102°C; time delayed about 10 seconds following starter disconnect |
| Temperature | LO ENG TEMP lamp setpoint | 70 | °F | 21°C or lower engine water jacket temperature |
| Temperature | Pre-high engine temperature alarm | 205 | °F | 97°C; optional 12-lamp system |
| Torque | Oil drain plug | 60-70 | ft.lb | also 81-95 N·m |
| Voltage | Electrical system starting voltage | 24 | Volts DC | |
| Voltage | Random voltage variation | ±1 | % | constant loads |
| Voltage | Rating condition, ambient temperature | 77 | °F | 25°C; also altitude 300 feet (92 m) |
| Voltage | Voltage adjust rheostat range | ±5 | % | optional; of rated output voltage |
| Voltage | Voltage regulation, VRAS-2 regulator | ±2 | % | from no load to full load |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Fluid | Grade | Standard | Ambient | Capacity | Notes |
|---|---|---|---|---|---|
| Coolant | Water or water/antifreeze mixture with DCA precharge | Water clean, low in mineral content, free of chloride, sulphate, or acid; permanent type antifreeze | New engines shipped with precharge water filter; precharge water filter compatible with plain water and all permanent antifreezes except methoxy propanol base; do not use antifreeze with anti-leak additives; capacities (standard radiator): 44 gallons (166 litres) 450 DM, 500 DM, 600 DFY; 42.5 gallons (161 litres) 450 DFW; 55 gallons (208 litres) 750 DFZ | ||
| Engine oil | SAE 5W synthetic | API class CC/CD; sulphated ash not exceeding 1.85 percent; pour point 9°F (5°C) below lowest expected temperature; viscosity 10,000 mPa*s max at -31°F (-35°C) and 4.1 mm2/s min at 212°F (100°C) | below -25°C | For ambient temperatures consistently below -13°F (-25°C) with no provision to keep engine warm; do not use petroleum base 5W grade oil | |
| Engine oil | SAE 10W-30 | API Class CC/CD, maximum sulphated ash 1.85 percent | -25°C to 35°C | -13°F to 95°F; capacities: 22.3 Gallons (84 litres) 450 DM, 500 DM, 600 DFY; 27 Gallons (102 litres) 450 DFW; 34 Gallons (129 litres) 750 DFZ (filters, lines and crankcase) | |
| Engine oil | SAE 15W-40 | API Class CC/CD | above -10°C | 14°F (-10°C) and above | |
| Engine oil | SAE 20W-40 | API Class CC/CD | above 0°C | 32°F (0°C) and above | |
| Fuel | No. 2 diesel | Engine primarily designed for No. 2 diesel fuels; will also operate on No. 1 fuel or similar if specifications met; filter or strain fuel as tank is filled | |||
| Grease | non-conductive grease | Light coating on battery terminals to retard corrosion | |||
| Other | anti-seize compound | Use when reassembling threaded aluminum parts (coolant heater) |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
⚠ Filters should be handled with care to prevent damage.
Tools: compressed air
Tools: compressed air
⚠ Do not use antifreeze with an anti-leak formula; the stop leak element can prevent or retard coolant flow through the filter.
⚠ Failure to remove AC power presents a shock hazard and can cause serious personal injury or death.
⚠ Contact with hot coolant can result in severe burns.
⚠ Excessive air pressure while starting the water flow could split the radiator core. Apply air pressure gradually.
Tools: flushing gun, compressed air
Tools: compressed air
⚠ Crankcase pressure can blow out hot oil and cause serious burns. Do NOT check oil while the generator set is operating.
Tools: drain pan, torque wrench
⚠ Do not permit any flame, cigarette, or other ignition source near the fuel system.
⚠ Always allow 15 minutes after engine shutdown before checking oil level.
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
The Cummins/Onan KTA-38-GI engine has an oil capacity of 129.0 liters.
The Cummins/Onan KTA-38-GI powers 1 generator set(s), including Cummins/Onan 750 DFZ.
A commonly reported issue on generators using the Cummins/Onan KTA-38-GI is: Starter has been locked out because of excessive cranking time..