Generac In-line Engine
The Generac In-line is a 1.5 L 4-cylinder naturally aspirated engine rated at 3600 rpm, producing up to 46.23 kW. It powers generator sets from Generac, including the In Line, QT022, QT027 and QT030. It holds 3.8 L (1.0 gal) of oil and 7.6 L (2.0 gal) of coolant.
Also known as: Generac In-line
Engine specifications
| Oil capacity | 3.8 L |
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| Coolant capacity | 7.6 L |
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| Displacement | 1.5 L |
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| Cylinders | 4 |
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| Aspiration | Naturally Aspirated |
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| Rated speed | 3600 rpm |
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| Gross power | 46 kW |
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Common problems
15- Warning active. SERVICE SCHEDULE C
Fix: Perform SERVICE SCHEDULE C maintenance; press ENTER to clear. - Warning active. SERVICE SCHEDULE B
Fix: Perform SERVICE SCHEDULE B maintenance; press ENTER to clear. - Warning active. SERVICE SCHEDULE A
Fix: Perform SERVICE SCHEDULE A maintenance; press ENTER to clear. - Warning active. LOW BATTERY
Fix: Clear alarm. From the MAIN menu on the control panel, navigate to the BATTERY MENU. Contact servicing dealer if battery is GOOD. Replace battery If CHECK BATTERY is displayed. - Warning active. CHARGER WARNING
Fix: Contact servicing dealer. - Warning active. BATTERY PROBLEM
Fix: Contact servicing dealer. - Unit will not start in AUTO with utility loss. UNDERVOLTAGE
Fix: Contact servicing dealer. - Unit will not start in AUTO with utility loss. UNDERSPEED
Fix: Contact servicing dealer. - Unit will not start in AUTO with utility loss. RPM SENSE LOSS
Fix: Clear alarm. From the MAIN menu on the control panel, navigate to the BATTERY MENU. Contact servicing dealer if battery is GOOD. Replace battery If CHECK BATTERY is displayed. - Unit will not start in AUTO with utility loss. OVERVOLTAGE
Fix: Contact servicing dealer. - Unit will not start in AUTO with utility loss. OVERSPEED
Fix: Contact servicing dealer. - Unit will not start in AUTO with utility loss. OVERCRANK
Fix: Clear alarm. Attempt to start the unit in MANUAL. If it does not start or starts and runs rough, contact servicing dealer. - Unit will not start in AUTO with utility loss. NOT ACTIVATED
Fix: Refer to activation section in Owner’s Manual. - Unit will not start in AUTO with utility loss. MISWIRE
Fix: Contact servicing dealer. - Unit will not start in AUTO with utility loss. LOW OIL PRESSURE
Fix: Check oil level. Add oil per Owner’s Manual. Contact servicing dealer if oil level is correct.
Compiled from service & troubleshooting documentation across every generator set that uses the Generac In-line.
Maintenance schedule
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
Service intervals
6| Item | Action | Hours | Months | Notes |
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| Replace fuel filter | Replace | 500 hr | | |
| Replace oil and filter | Change | 500 hr | | |
| Drain/flush coolant system | Drain | 1000 hr | | |
| Check coolant level and hoses | Check | | | First service |
| Check fuel level | Check | | | First service |
| Check oil level | Check | | | First service |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Service specifications
9| Type | Item | Value | Unit | Condition |
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| Other | Total Harmonic Distortion | <5% | | |
| Pressure | LP fuel pressure | 7-14 | in Water Column | fuel system |
| Pressure | NG fuel pressure | 3.5-14 | in Water Column | fuel system |
| Speed | Frequency regulation (steady state) | 0.25 | % | isochronous operation |
| Speed | Steady State Regulation (Governor) | ±0.25% | | |
| Temperature | Operating temperature rise above ambient | 120 | °C | above 40°C ambient |
| Torque | Operating temperature rise | 120 | °C above 40°C ambient | rated output |
| Voltage | Voltage Regulation | ±1% | | |
| Voltage | Voltage regulation | 1 | % | steady state |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Recommended fluids
| Fluid | Grade | Standard | Ambient | Capacity | Notes |
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| Coolant | Ethylene glycol 50/50 mix | | | 11.0 l | RG048: 11 l, RG060/RG080: 17 l |
| Coolant | Peak Fleet-Charge 50/50 ethylene glycol | | -20°C to 48°C | 2.8 gal | Use demineralized or distilled water base |
| Engine oil | 15W-40 | API Service Class CD or better | -20°C to 48°C | | Synthetic oil can be used in appropriate weight |
| Fuel | Ultra Low Sulfur Diesel | | below 40°C | | Mechanical engine-driven pump, 5 micron filter (15/20/30 kW), 10 micron filter (48/50 kW) |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Fault codes
6| Code | Name | Meaning | Severity | Action |
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| HIGH TEMPERATURE | High Temperature | Engine coolant temperature exceeds limit | Shutdown | |
| LOW OIL PRESSURE | Low Oil Pressure | Oil pressure below acceptable level | Warning | |
| NOT ACTIVATED | Not Activated | Unit will not start in AUTO with utility loss | Info | |
| OVERCRANK | Overcrank | Engine overcrank fault | Warning | |
| OVERLOAD | Overload | Unit overloaded, shuts down during operation | Shutdown | |
| RPM SENSE LOSS | RPM Sense Loss | Loss of engine RPM signal | Shutdown | |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Voltage reconnection
| Voltage | Phase | Connection | Leads | Notes |
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| 120/208 | 3 | 6 wire | 3-Phase 6 wire alternator output | Power factor 0.8 |
| 120/208 | 3 | Three phase | RD015, RD020, RD030, RD050 | |
| 120/240 | 1 | 4 wire | 1-Phase 4 wire alternator output | Power factor 1.0 |
| 120/240 | 1 | Single phase | RD015, RD020, RD030, RD048 | |
| 120/240 | 3 | 6 wire | 3-Phase 6 wire alternator output | Power factor 0.8 |
| 120/240 | 3 | Three phase | RD015, RD020, RD030, RD048, RD050 | |
| 277/480 | 3 | 6 wire | 3-Phase 6 wire alternator output | Power factor 0.8 |
| 277/480 | 3 | Three phase | RD030, RD048, RD050 | |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Common questions
What is the oil capacity of the Generac In-line?
The Generac In-line engine has an oil capacity of 3.8 liters.
What is the displacement of the Generac In-line?
The Generac In-line has a displacement of 1.5 liters with 4 cylinders.
Which generators use the Generac In-line engine?
The Generac In-line powers 26 generator set(s), including Generac In Line, Generac QT022, Generac QT027, Generac QT030, Generac QT036.
How often should you change the oil in the Generac In-line?
The Generac In-line oil change interval is every 500 hours.
What is a common problem with the Generac In-line engine?
A commonly reported issue on generators using the Generac In-line is: Warning active. SERVICE SCHEDULE C. Fix: Perform SERVICE SCHEDULE C maintenance; press ENTER to clear..