The Caterpillar SR4 is a 34.5 L engine rated at 1200 rpm, producing up to 675 kW. It powers generator sets from Caterpillar, including the 3508 and 3512.
Also known as: Caterpillar SR4
| Displacement | 34.5 L |
|---|---|
| Rated speed | 1200 rpm |
| Gross power | 675 kW |
| Symptom | Cause | Remedy |
|---|---|---|
| The engine will be shutdown by means of the fuel control and a diagnostic code will be displayed. | If the signal from the engine mounted oil pressure/temperature transducer module is lost or unreadable | Refer to the Service Manual Module SENR3535, which is included in the Service Manual SENR7958 for programming instructions and diagnostic fault codes. |
| The engine will be shutdown by means of the air and fuel control and a diagnostic code will be displayed. | If the ECM loses its magnetic pickup signal | Refer to the Service Manual Module SENR3535, which is included in the Service Manual SENR7958 for diagnostic fault codes. |
| The engine will shutdown by means of the fuel control and the Overspeed LED will flash. | If the engine speed exceeds the overspeed setpoint | Lower the overspeed setpoint to 75% of its original value while the overspeed verify switch is depressed. This allows the overspeed circuit to be tested while a generator set is operating at rated speed. |
| The engine will be shutdown by means of the fuel control and the Low Oil Pressure LED will flash. | If the engine oil pressure drops below the low oil pressure setpoint | |
| The engine will shutdown by means of the fuel control and the High Coolant Temperature LED will flash. | If the engine coolant temperature exceeds the high coolant temperature setpoint | |
| The red fault shutdown indicator flashes when the GSC detects a fault that is a shutdown condition. | Refer to SENR5809 for fault code descriptions. | |
| Overcrank Protection - If the engine fails to start in a preprogrammed amount of time, the ECM will halt the starting sequence and flash the Overcrank LED. | Another attempt to start the engine cannot be made without first going to the offlreset position on the engine control switch (ECS). | |
| Check for loose or corroded terminals. | Make sure wire connections are correct. |
Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.
Compiled from service & troubleshooting documentation across every generator set that uses the Caterpillar SR4.
Step-by-step procedures compiled from the Caterpillar service manual for this engine.
| Item | Action | Hours | Months | Notes |
|---|---|---|---|---|
| System | Test | 1 hr | ToCI quarterly: exercise system under full load for 1 hour | |
| Cooling System Coolant Level | Check | 8 hr | Daily | |
| Driven Equipment | Other | 8 hr | Daily; Inspect/Replace/Lubricate | |
| Engine Air Cleaner Differential Pressure | Check | 8 hr | Daily | |
| Engine Air Precleaner | Clean | 8 hr | Daily | |
| Engine Oil Filter Differential Pressure | Check | 8 hr | Daily | |
| Engine Oil Level | Check | 8 hr | Daily | |
| Fuel System Fuel Filter Differential Pressure | Check | 8 hr | Daily | |
| Fuel System Primary Filter/Water Separator | Drain | 8 hr | Daily | |
| Fuel Tank Water and Sediment | Drain | 8 hr | Daily | |
| Instrument Panel | Inspect | 8 hr | Daily | |
| Walk-Around Inspection | Inspect | 8 hr | Daily | |
| Zinc Rods | Inspect | 50 hr | Inspect/Replace | |
| Alternator and Fan Belts | Inspect | 250 hr | Every 250 Service Hours; Inspect/Adjust/Replace | |
| Battery Electrolyte Level | Check | 250 hr | Every 250 Service Hours | |
| Belts | Adjust | 250 hr | ||
| Belts | Inspect | 250 hr | Inspect/Adjust/Replace; Every 250 Service Hours | |
| Cooling System Coolant Sample (Level 1) | Other | 250 hr | Obtain; Every 250 Service Hours | |
| Cooling System Supplemental Coolant Additive (SCA) | Test | 250 hr | Test/Add; Every 250 Service Hours | |
| Engine Oil Sample | Other | 250 hr | Obtain; Every 250 Service Hours | |
| Engine Oil Sample | Test | 250 hr | Every 250 Service Hours - Obtain | |
| Engine Valve Lash | Adjust | 4000 hr | First service — Inspect/Adjust; Initial 250 Service Hours | |
| Fan Drive Bearing | Lubricate | 250 hr | Every 250 Service Hours | |
| Fuel Injector | Adjust | 4000 hr | First service — Inspect/Adjust; Initial 250 Service Hours | |
| Fuel System Primary Filter | Clean | 250 hr | Every 250 Service Hours; Clean/Inspect/Replace | |
| Fuel System Primary Filter | Replace | 1000 hr | Every 250 Service Hours; Clean/Inspect/Replace | |
| Fuel System Secondary Filter | Replace | 1000 hr | Every 250 Service Hours | |
| Hoses and Clamps | Inspect | 250 hr | Inspect/Replace; Every 250 Service Hours | |
| Magnetic Pickups | Clean | 6000 hr | 72 mo | First service — Initial 250 Service Hours; Clean/Inspect |
| Magnetic Pickups | Inspect | 6000 hr | 72 mo | First service — Initial 250 Service Hours (or at first oil change); Clean/Inspect |
| Radiator | Clean | 250 hr | Every 250 Service Hours | |
| Speed Sensor | Clean | 6000 hr | 72 mo | First service — Initial 250 Service Hours; Clean/Inspect |
| Air Shutoff | Test | 500 hr | Every 500 Service Hours (Prime Power) | |
| Cooling System Coolant Sample (Level 1) | Test | 500 hr | Every 500 Service Hours (Prime Power) | |
| Cooling System Coolant Sample (Level 2) | Test | 500 hr | First service — Initial 500 Hours for new, refilled and converted systems | |
| Engine Oil and Filter | Change | 1000 hr | Every 500 Service Hours - standard sump; deep sump every 1000 hours | |
| Cooling System Coolant Analysis (Level II) | Other | 1000 hr | Every 1000 Service Hours; Obtain | |
| Cooling System Coolant Sample (Level 2) | Other | 1000 hr | 12 mo | First service — Obtain; Every 1000 Service Hours |
| Engine | Clean | 1000 hr | Every 1000 Service Hours | |
| Engine Crankcase Breather | Clean | 1000 hr | Every 1000 Service Hours |
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 shutoff damper plunger distance A (minimum) | 18.3 | mm | 0.72 inch; replace plunger if less |
| Clearance | Air shutoff damper plunger distance A (replace if less than) | 18.3 | mm | |
| Clearance | Coolant level below bottom of filler pipe | 13 | mm | no sight gauge |
| Clearance | Coolant level below filler pipe bottom (no sight gauge) | 13 | mm (0.5 in) | |
| Clearance | Crankshaft end play | .178 to .635 | mm (0.0070 to 0.0250 inch) | measured with dial indicator |
| Clearance | Crankshaft end play after assembly | 0.178 to 0.635 | mm (0.0070 to 0.0250 inch) | after assembly |
| Clearance | Crankshaft vibration damper plunger - minimum wear dimension A | 18.3 | mm (0.72 in) | |
| Clearance | End play at heat sink after assembly | 0.076 to 0.635 | mm (0.0030 to 0.0250 inch) | after assembly |
| Clearance | Gap at 3, 6, 9, 12 o'clock positions | 0.03 to 0.13 | mm (0.001 to 0.005 inch) | between |
| Clearance | Gap between generator and flywheel housing at locations (E), (F), (G), (H) | >0.03 and <0.13 | mm (0.001 inch to 0.005 inch) | more than 0.03 mm and less than 0.13 mm |
| Clearance | Generator forward offset from midpoint of end play | + 0.50 | mm (+ 0.0200 inch) | while generator supported by crane |
| Clearance | Rotor end play | 3.81 to 7.62 | mm (.150 to .300 inch) | approximately |
| Clearance | Shim thickness divisor for number of shims | 0.8 | mm (0.03 inch) | divide Letter L by this value |
| Clearance | Speed/timing sensor sliphead extension | 4 | mm | minimum |
| Clearance | Support deflection during bolt tightening | 0.13 | mm (0.005 inch) | maximum allowed movement |
| Gap | Air shutoff damper plunger distance A (replace if less) | 18.3 | mm | |
| Gap | Coolant level below bottom of filler pipe (no sight gauge) | within 13 | mm (.5 inch) | |
| Other | Air cleaner element cleaning limit | six times | replace at least once per year regardless | |
| Other | Air starting motor lubricator oil release rate | two drops per 30 seconds | constant rate of air flow | |
| Other | Altitude capability without derate | 1525 | m | |
| Other | Altitude capability without derate | 800 | m | |
| Other | Coolant Sample (Level 1) interval for Cat DEAC | 250 | hours | |
| Other | Cooling system cleaner amount (heavy deposits) | 0.5 | L per 3.8 to 7.6 L capacity | 1 pint per 1 to 2 US gal |
| Other | Cooling system cleaner amount (normal deposits) | 0.5 | L per 15 L capacity | 1 pint per 4 US gal |
| Other | Cooling system cleaner dosage - heavy deposits or plugging | 0.5 L per 3.8 to 7.6 L | (1 pint per 1 to 2 US gal) | |
| Other | Cooling system cleaner dosage - normal | 0.5 L per 15 L | (1 pint per 4 US gal) | |
| Other | Cooling system cleaning duration (heavy deposits) | 90 | minutes | minimum, coolant at least 82 C (180 F) |
| Other | Cooling system cleaning duration (normal deposits) | 30 | minutes | minimum, coolant at least 82 C (180 F) |
| Other | Cooling system fill rate | 19 | L/min | maximum |
| Other | Cooling system fill rate | no faster than 19 | L (5 US gal) per minute | to avoid air locks |
| Other | Cooling system fill rate maximum | 19 | L/min | |
| Other | Crankshaft vibration damper max temperature | 93 | °C (200°F) | during operation, infrared thermometer check |
| Other | Crankshaft vibration damper without sampling port - max life | 20000 | hours | |
| Other | Damper fluid viscosity degradation limit | 20 | percent | majority of applications |
| Other | Damper fluid viscosity degradation limit (Hasse & Wrede) | 20 | percent | majority of applications |
| Other | Damper operating hours before rebuild/replace (damper without sampling port) | 20000 | hours | |
| Other | Damper without sampling port - rebuild/replace interval | 20000 | hours | or at major overhaul |
| Other | Exercise under full load | 1 | hour | ToCI quarterly |
| Other | Fast Acting Cooling System Cleaner amount | 0.5 L per 15 L | L | cooling system capacity, normal deposits |
| Other | Fast Acting Cooling System Cleaner amount | 0.5 L per 3.8 to 7.6 L | L | cooling system capacity, heavy deposits |
| Other | Fuel (secondary) filter tightening after gasket contacts base | one full turn | by hand, do not overtighten | |
| Other | Full load test duration | 4 | hours | Once per year |
| Other | Gross Input Torque (TH55-E70) | 12 667 | N•m (9350 lb-ft) | |
| Other | Gross Input Torque (TH55-E90) | 12 677 | N•m (9350 lb-ft) | |
| Other | Hydrosolv cleaner concentration | 2 to 5 | percent | temperatures up to 93 C (200 F) |
| Other | Load bank data recording interval | 15 | minutes | During load bank test |
| Other | Load bank test load level | 80 | % of generator nameplate capacity | 4-hour resistive load bank test |
| Other | Load bank test profile | 2 hours at 50%, 1 hour at 75%, 1 hour at 100% | Annual four (4) hour load bank test | |
| Other | Major Overhaul interval (fuel consumption basis) | 1575000 | L (416,070 US gal) | at approximately 60 percent load factor, 3512B engines |
| Other | Max cooling system fill rate (avoid air locks) | 19 | L per minute (5 US gal per minute) | |
| Other | Max supplemental coolant additive (SCA) concentration - coolant/antifreeze and SCA | 6 | percent | |
| Other | Max supplemental coolant additive (SCA) concentration - water and SCA | 8 | percent | |
| Other | Maximum air pressure at nozzle for cleaning purposes | 205 | kPa | 30 psi |
| Other | New drive belt tension recheck after operation | 30 | minutes | rated rpm |
| Other | Rating condition (diesel 7 L and higher) | 99 kPa (29.31 in Hg) dry barometer, 25°C (77°F) | SAE J1995 inlet air standard | |
| Other | Rating condition (diesel up to 6.6 L) | 100 kPa (29.5 in Hg) total barometric pressure, 1 kPa (.295 in Hg) vapor pressure, 25°C (77°F) | ISO/TR14396 inlet air standard | |
| Other | Rating condition (gas) | 100 kPa (29.61 in Hg) and 25°C (77°F) | SAE J1349 standard | |
| Other | Speed/timing sensor sliphead tension force | 22 | N | minimum; to push in sliphead from the extended position |
| Other | Stall Torque Ratio (TH55-E70) | 2.23 | ||
| Other | Stall Torque Ratio (TH55-E90) | 2.23 |
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 | Cat DEAC | Diesel; 3,000 Service Hours or Three Years; annual S·O·SSM Level 2 coolant sampling and analysis | |||
| Coolant | Cat DEAC (Diesel Engine Antifreeze/Coolant) | Conventional coolant; SCA required; see SEBU6251 | |||
| Coolant | Cat DEAC or Cat ELC (Extended Life Coolant) | Caterpillar EC-1 | 50/50 mixture recommended, ELC requires only clean water flush | ||
| Coolant | Cat ELC | Diesel; 12,000 Service Hours or Six Years; add Cat ELC Extender at 6,000 service hours or one half of service life; annual S·O·SSM Level 2 coolant sampling and analysis | |||
| Coolant | Cat ELC (Extended Life Coolant) | Add Cat ELC Extender once; do not use conventional SCA with Cat ELC | |||
| Coolant | Cat ELC Extender | Add once; use only with Cat ELC | |||
| Coolant | Cat NGEC | Natural Gas; 16,000 Service Hours or Three Years; use interval that occurs first | |||
| Coolant | Clean water | Use only clean water to flush the cooling system when Extended Life Coolant (ELC) is drained and replaced | |||
| Coolant | Commercial long life / heavy-duty coolant meeting Caterpillar EC-1 | Caterpillar Engine Coolant Specification -1 (EC-1) | Obtain Level 1 coolant sample | ||
| Coolant | Commercial long life coolant meeting Caterpillar EC-1 | Caterpillar Engine Coolant Specification -1 (EC-1) | |||
| Coolant | DEAC (conventional coolant/antifreeze) | Requires Supplemental Coolant Additive (SCA); do not exceed 6 percent SCA concentration with coolant/antifreeze, 8 percent with water and SCA | |||
| Coolant | Extended Life Coolant (ELC) | Caterpillar ELC | Requires only one addition of Extender; fill no faster than 19 L (5 US gal) per minute | ||
| Coolant | Supplemental Coolant Additive (SCA) | Max 6 percent with conventional coolant; max 8 percent with water and SCA | |||
| Engine oil | EPA 2D 89.330-96 (fuel reference, Diesel <6.6 L, density 0,845-0,850 kg/L a 15 °C) | Reference condition only, not a lubricant recommendation | |||
| Engine oil | Cat NGEO | Natural Gas | |||
| Engine oil | air tool oil | below 0°C | Air starting motor lubricator; temperatures below 0 C (32 F) | ||
| Engine oil | low sulfated ash oil | Required for U.S. EPA Tier 4 Final, EU Stage IV engines. | |||
| Engine oil | meeting manufacturer's specs | Add crankcase oil (grade meeting manufacturer's specs) to correct level (SCI) | |||
| Engine oil | Cat Arctic DEO SYN SAE 0W-30 | -40°C to 30°C | Engine Crankcase; Industrial Engines | ||
| Engine oil | Cat DEO SYN SAE 5W-40 | -30°C to 50°C | Engine Crankcase; Industrial Engines | ||
| Engine oil | Cat DEO SAE 10W-30 | -18°C to 40°C | Engine Crankcase; Industrial Engines | ||
| Engine oil | Cat DEO SAE 15W-40 | -9°C to 50°C | Engine Crankcase; Industrial Engines | ||
| Engine oil | 10W (nondetergent) | above 0°C | Air starting motor lubricator bowl oil for temperatures greater than 0°C (32°F) | ||
| Engine oil | nondetergent SAE 10W | above 0°C | Air starting motor lubricator; temperatures greater than 0 C (32 F) | ||
| Fuel | Ultra Low Sulfur Diesel (ULSD) | Contains less than or equal to 15 parts per million sulfur (mg/kg); required for U.S. EPA Tier 4 Final, EU Stage IV engines. B20 biodiesel capability available. | |||
| Fuel | 35° API gravity at 60°F (16°C) | LHV 18,390 Btu/lb (42 780 kJ/kg) | Fuel at 85°F (29°C) weighing 7.001 lbs/U.S. gal (838.9 g/liter) | ||
| Fuel | 35° API gravity, LHV 42 780 kJ/kg (18,390 btu/lb) | SAE J1995 | Diesel engines 7 liter and higher; used at 29°C (84.2°F) with density 838.9 g/L | ||
| Fuel | EPA 2D 89.330-96 | EPA 2D 89.330-96 | Diesel engines up to 6.6 liter; density 0.845-0.850 kg/L @ 15°C (59°F); fuel inlet temperature 40°C (104°F) | ||
| Fuel | No. 2 fuel | 3600 engines designed for 80 000 hours on No. 2 fuel; ratings based on API gravity of 35 at 15 C (60 F), LHV of 42 780 kJ/kg used at 29 C (84 F) with a density of 838.9 g/L | |||
| Fuel | dry natural gas, LHV 35.54 MJ/Nm3 (905 btu/ft3) | Gas ratings based on SAE J1349 standard conditions of 100 kPa (29.61 in Hg) and 25°C (77°F) |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Tools: crane, dial indicator, shims, torque wrench
Tools: shims, torque wrench
⚠ Slippage of loose belts can reduce efficiency of driven components
⚠ Too tight belts place unnecessary stress on components
⚠ Ensure engine cannot be started during maintenance
⚠ Allow engine to cool before measuring/adjusting valve lash
⚠ Damage to cylinder block can result if timing pins are not removed before turning crankshaft
Tools: torque wrench, shims
⚠ Do not start the engine during the test
⚠ Ensure the engine control is in the OFF position
⚠ Check the wiring for the air shutoff switches, and for the solenoids
⚠ High voltage can cause electrocution. Discharge instrument leads and generator windings.
Tools: 300-8648 Insulation Testing Gp
⚠ Damage to engine and generator can result if electric set is operated with a plate assembly that does not have proper clearance.
⚠ If N or O is less than initial A, disassemble and check coupling plate for bowing; replace if bowed.
Tools: dial indicator, straight edge, magnetic bases, crane, torque wrench, 17 5N-4478 Plates
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
| Voltage | Phase | Connection | Leads | Notes |
|---|---|---|---|---|
| 600 | 3 | wye (10 wire) | 10 wire | Brushless SR4B generator; 0.7 pf; voltage regulator optional; space heater and 100 ohm platinum temperature detectors standard |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.
The Caterpillar SR4 has a displacement of 34.5 liters.
The Caterpillar SR4 powers 2 generator set(s), including Caterpillar 3508, Caterpillar 3512.
A commonly reported issue on generators using the Caterpillar SR4 is: Warning tag attached to the engine start switch or controls. Fix: Do NOT start the engine or move the controls. Consult with the person that attached the warning tag before starting..