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Caterpillar 3512C ATAAC Engine

The Caterpillar 3512C ATAAC is a 51.8 L 12-cylinder ta engine rated at 1800 rpm. It powers generator sets from Caterpillar, including the SR4B.

Also known as: CAT 3512C ATAAC

Part of the Caterpillar 3512C engine family — 4 variants share parts & fitment.

51.8 L

Displacement

Cylinders

1800 rpm

Rated speed

On this pageSpecs Generator sets FAQ Service intervals Torque & specs Fluids Fault codes Procedures Wiring

Engine specifications

Displacement	51.8 L
Cylinders	12
Aspiration	TA
Rated speed	1800 rpm

Generator sets powered by this engine

Caterpillar SR4B

How to read your Caterpillar engine serial & model number →

Common problems

When the engine oil pressure is increased beyond the low oil pressure setpoint, the GSC will inform the governor that the engine speed should be increased from IDLE to RATED rpm. 2301A Control
The fault alarm indicator (3) flashes when the GSC detects an alarm fault. g00604607
Overcrank — The engine does not start within the setpoint for total cycle crank time that is programmed into the GSC; the overcrank indicator FLASHES; the engine is not allowed to start until the fault is corrected
Cause: The engine does not start within the setpoint for total cycle crank time that is programmed into the GSC
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
Overcrank (GSC+) — The engine does not start within the setpoint for total cycle crank time that is programmed into the GSC+; the overcrank indicator FLASHES; the engine is not allowed to start until the fault is corrected
Cause: The engine does not start within the setpoint for total cycle crank time that is programmed into the GSC+
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
Low Oil Pressure — The engine oil pressure drops below the setpoints for low oil pressure shutdown that are programmed into the GSC; the low oil pressure indicator FLASHES, and the engine is shut down; the engine is not allowed to start until the fault is corrected
Cause: The engine oil pressure drops below the setpoints for low oil pressure shutdown that are programmed into the GSC
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
Low Oil Pressure (GSC+) — The engine oil pressure drops below the setpoints for low oil pressure shutdown that are programmed into the GSC+; the low oil pressure indicator FLASHES, and the engine is shut down; the engine is not allowed to start until the fault is corrected
Cause: The engine oil pressure drops below the setpoints for low oil pressure shutdown that are programmed into the GSC+
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
Low Coolant Level — The engine coolant level drops below the probe of the coolant loss sensor; the engine coolant level indicator FLASHES; the engine is shut down; the engine is not allowed to start until the fault is corrected
Cause: The engine coolant level drops below the probe of the coolant loss sensor
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
High Water Temperature — The engine coolant temperature rises above the setpoint for high water temperature shutdown that is programmed into the GSC; the high water temperature indicator FLASHES; the engine is shutdown and the engine is not allowed to start until the fault is corrected
Cause: The engine coolant temperature rises above the setpoint for high water temperature shutdown that is programmed into the GSC
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
High Water Temperature (GSC+) — The engine coolant temperature rises above the setpoint for high water temperature shutdown that is programmed into the GSC+; the high water temperature indicator FLASHES; the engine is shutdown and the engine is not allowed to start until the fault is corrected
Cause: The engine coolant temperature rises above the setpoint for high water temperature shutdown that is programmed into the GSC+
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
Fault shutdown 21
Fault alarm 22
Engine Overspeed — The engine speed exceeds the setpoint for engine overspeed that is programmed into the GSC; the engine overspeed indicator FLASHES; the engine is shutdown and the engine is not allowed to start until the fault is corrected
Cause: The engine speed exceeds the setpoint for engine overspeed that is programmed into the GSC
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
Engine Overspeed (GSC+) — The engine speed exceeds the setpoint for engine overspeed that is programmed into the GSC+; the engine overspeed indicator FLASHES; the engine is shutdown and the engine is not allowed to start until the fault is corrected
Cause: The engine speed exceeds the setpoint for engine overspeed that is programmed into the GSC+
Fix: Correct the fault; the engine is not allowed to start until the fault is corrected
Emergency Stop — The operator presses the emergency stop push button (ESPB) on the front panel; the emergency stop indicator FLASHES and the engine is shut down; the engine is not allowed to start until the condition is corrected
Cause: The operator presses the emergency stop push button (ESPB) on the front panel
Fix: Correct the condition; the engine is not allowed to start until the condition is corrected
Emergency Stop (GSC+) — The operator presses the emergency stop push button (ESPB) on the front panel; the emergency stop indicator FLASHES and the engine is shut down; the engine is not allowed to start until the condition is corrected
Cause: The operator presses the emergency stop push button (ESPB) on the front panel
Fix: Correct the condition; the engine is not allowed to start until the condition is corrected

Compiled from service & troubleshooting documentation across every generator set that uses the Caterpillar 3512C ATAAC.

Service intervals

Item	Action	Hours	Months	Notes
Aftercooler Core	Clean	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Clean/Test
Alternator and Fan Belts	Inspect	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby); Inspect/Adjust/Replace
Battery Electrolyte Level	Check	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Week (Standby)
Cooling System Supplemental Coolant Additive (SCA)	Test	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby); Test/Add
Cylinder Head Grounding Stud	Inspect	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every 3 Years (Standby); Inspect/Clean/Tighten
Engine Crankcase Breather	Clean	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby)
Engine Oil Sample	Other	250 hr		Obtain; Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby)
Engine Oil and Filter	Change	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby)
Engine Protective Devices	Check	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby)
Engine Valve Lash	Inspect	3000 hr		First service — First 9500 L (2500 US gal) of Fuel or 250 Service Hours (Prime Power); Inspect/Adjust
Fan Drive Bearing	Lubricate	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby)
Fuel System Secondary Filter	Replace	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby)
Fuel Tank Water and Sediment	Drain	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Week (Standby)
Hoses and Clamps	Inspect	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby); Inspect/Replace
Magnetic Pickups	Clean	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Clean/Inspect
Radiator	Clean	250 hr		Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every Year (Standby)
Rotating Rectifier	Check	7500 hr	12 mo	Every 9500 L (2500 US gal) of Fuel or 250 Service Hours or Yearly (Prime Power); Every 3 Years (Standby)
Fuel System Primary Filter (Water Separator) Element	Replace	500 hr		Every 19 000 L (5000 US gal) of Fuel or 500 Service Hours (Prime Power); Every Year (Standby)
Alternator	Inspect	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 2 Years (Prime Power); Every Year (Standby)
Cooling System Coolant (DEAC)	Change	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every 3 Years (Standby)
Cooling System Coolant Extender (ELC)	Other	3000 hr		Add; Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every 3 Years (Standby)
Cooling System Water Temperature Regulator	Replace	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every 3 Years (Standby)
Crankshaft Vibration Damper	Inspect	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 2 Years (Prime Power); Every Year (Standby)
Engine Mounts	Inspect	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every Year (Standby)
Engine Speed/Timing Sensors	Check	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every 3 Years (Standby); Check/Clean/Calibrate
Engine Valve Rotators	Inspect	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every Year (Standby)
Starting Motor	Inspect	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every Year (Standby)
Turbocharger	Inspect	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every 3 Years (Standby)
Water Pump	Inspect	3000 hr		Every 114 000 L (30 000 US gal) of Fuel or 3000 Service Hours or 3 Years (Prime Power); Every Year (Standby)
Insulation	Test	7500 hr	12 mo	Every 7500 Service Hours or 1 Year (Standard and Standby schedule)
Cooling System Coolant (ELC)	Change	12000 hr		Every 228 000 L (60 000 US gal) of Fuel or 12 000 Service Hours or 6 Years (Prime Power); Every 6 Years (Standby)
Bearing (Ball)	Lubricate	2000 hr	12 mo	Every Year (Standby schedule)
Bearing (Spherical Roller)	Lubricate	1000 hr	12 mo	Every Year (Standby schedule)
Generator Set Vibration	Inspect	2000 hr	12 mo	Every Year (Standby schedule)
Stator Lead	Check	2000 hr	6 mo	Every 6 Months (Standby schedule)

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

Type	Item	Value	Unit	Condition
Clearance	Bearing bracket step minimum	less than 0.0762	mm
Clearance	Coolant level below bottom of filler pipe	13	mm	engine stopped and cool
Clearance	Fan and alternator belt deflection	13 to 19	mm	110 N (25 lb) force midway between pulleys
Other	High idle speed for droop governors	approximately 2% to 5%	above full load speed	governors equipped with droop
Other	SCA concentration in glycol/water mixture	3 to 6	percent	glycol and water
Other	SCA concentration in water-only mixture	6 to 8	percent	water and SCA
Other	Speed droop values commonly used	3% and 0%	%
Other	Voltage droop for 0.8 power factor load	approximately 5	%	loads with a power factor of 0.8
Pressure	Engine oil pressure at low idle	186 to 344	kPa	low idle speed
Pressure	Engine oil pressure at rated engine speed	275 to 606	kPa	at rated engine speed
Pressure	Engine oil pressure at rated engine speed	40 to 88	psi	at rated engine speed
Pressure	Maximum air pressure for cleaning	205	kPa	cleaning purposes
Pressure	Maximum water pressure for cleaning	275	kPa	cleaning purposes
Pressure	Normal operating engine oil pressure	275 to 600	kPa	engine running at rated engine speed, SAE 10W30 oil, operating oil temperature 104 C (219.2 F), normal engine water temperature
Resistance	Exciter Armature (Rotor) (L2) resistance	less than 0.1	ohm	room temperature
Resistance	Exciter Armature (Rotor) (L2) winding resistance	less than 0.1	ohm	room temperature
Resistance	Exciter Field (Stator) (L1) resistance	3.0 to 6.0	ohms	room temperature
Resistance	Exciter Field (Stator) (L1) winding resistance	3.0 to 6.0	ohm	room temperature
Resistance	Insulation resistance minimum for other windings	100,000	ohms	drying decision
Resistance	Insulation resistance minimum for stator	1	megohm	drying decision
Resistance	Main Armature (Stator) (L4) resistance	less than 0.1	ohm	room temperature
Resistance	Main Field (Rotor) (L3) resistance	0.75 to 2.0	ohms	room temperature
Resistance	Main Field (Rotor) (L3) winding resistance	0.75 to 2.0	ohm	room temperature
Resistance	Main armature (Stator) (L4) winding resistance	less than 0.1	ohm	room temperature
Resistance	Pilot Exciter Armature (L5) resistance	less than 0.1	ohm	room temperature
Resistance	Pilot Exciter Armature (L5) winding resistance	less than 0.1	ohm	room temperature
Resistance	Resistor (R5) resistance	27000	ohm	nominal ± 2700 ohms
Resistance	Varistor (CR7) resistance	15000	ohm	minimum
Resistance	Varistor (CR7) resistance	minimum 15000	ohms
Speed	Frequency vs RPM - four-pole generator	divide the RPM by 30	Hz
Speed	Frequency vs RPM - six pole generator	divide the RPM by 20	Hz
Speed	Low idle (50 Hz units)	approximately 80	% of full load speed	50 Hz units
Speed	Low idle (60 Hz units)	approximately 66	% of full load speed	60 Hz units
Temperature	Bearing installation heating	149	C	for press fit installation
Temperature	Bearing reinstall heating	107	C	heat for ten minutes
Temperature	Bearing temperature shutdown threshold above ambient	50	°C	above ambient
Temperature	Coupling installation heating	315	C	for press fit installation
Temperature	Engine coolant temperature typical range	87 to 98	°C
Temperature	Engine water temperature operating range	88 to 100	C	88 C (190.4 F) to 100 C (212.0 F)
Temperature	Generator drying temperature (oven method)	65	C	forced air oven for 4 hours
Temperature	Generator drying winding temperature rise rate	10	C per hour up to 85 C (185 F)	do not apply heat too rapidly
Temperature	Hub reinstall heating	400	C	heat for three hours
Temperature	Maximum allowable coolant temperature with pressurized cooling system	107	°C	pressurized cooling system
Temperature	Maximum exhaust temperature	575	°C
Temperature	Maximum oil temperature at rated speed with full load	107	°C	rated speed, full load
Temperature	Oven drying method temperature	65	C	forced air drying oven for four hours
Temperature	Winding temperature limit during drying	85	C	maximum to prevent insulation damage
Torque	Air cleaner service indicator	18	lb in	install
Torque	Air cleaner service indicator	2	N·m	install
Torque	Exciter armature bolt (3/8 inch)	55.8	N·m	with thread lock 9S-3263
Torque	Exciter armature bolt (5/16 inch)	35.4	N·m	with thread lock 9S-3263
Voltage	Generator set functional test minimum phase voltage	minimum 85	VAC	generator set operated at half the rated speed with 12 VDC battery on F1+/F2-
Voltage	Insulation test voltage for units 600 V or less	500	V	insulation test
Voltage	Insulation test voltage for units 600 volts or less	500	Volts	600 volts or less
Voltage	Insulation test voltage for units more than 600 V	1000	V	insulation test
Voltage	Insulation test voltage for units more than 600 volts	1000	Volts	more than 600 volts

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
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)	ASTM D4985 or ASTM D5345		22.7 L	Acceptable
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)	Caterpillar EC-1		22.7 L	Preferred; engine only capacity; 1:1 water and glycol recommended
Coolant	Cat NGEC				Natural Gas; 16,000 Service Hours or Three Years; use interval that occurs first
Engine oil	Cat NGEO				Natural Gas
Engine oil	SAE 10W30				Referenced as the oil used when normal operating engine oil pressure is specified
Engine oil	Cat Arctic DEO SYN SAE 0W-30		-40°C to 30°C		Engine Crankcase; Industrial Engines
Engine oil	SAE 0W-20		-40°C to 10°C		Cat DEO or equivalent
Engine oil	SAE 0W-30		-40°C to 30°C
Engine oil	SAE 0W-40		-40°C to 40°C
Engine oil	Cat DEO SYN SAE 5W-40		-30°C to 50°C		Engine Crankcase; Industrial Engines
Engine oil	SAE 5W-30		-30°C to 30°C
Engine oil	SAE 5W-40		-30°C to 50°C
Engine oil	Cat DEO SAE 10W-30		-18°C to 40°C		Engine Crankcase; Industrial Engines
Engine oil	SAE 10W-30		-18°C to 40°C		Cat DEO (Diesel Engine Oil) 10W-30
Engine oil	SAE 10W-40		-18°C to 50°C
Engine oil	Cat DEO SAE 15W-40		-9°C to 50°C		Engine Crankcase; Industrial Engines
Engine oil	SAE 15W-40		-9°C to 50°C		Cat DEO (Diesel Engine Oil) 15W-40
Fuel	No. 1-D or No. 2-D diesel	ASTM D975			No. 1 or blend best for cold weather
Grease	Cat Generator Set Grease				Part Number 108-8611
Grease	MPGM or Bearing Lubricant				Fan drive bearing and battery terminals
Grease	NLGI No. 1.5 Grade				Caterpillar 108-8611 Grease Cartridge for spherical roller bearings; contains Clay thickener; no molybdenum disulfide; viscosity 32 cSt at 40 C, 5 cSt at 100 C
Grease	NLGI No. 2 Grade		-29°C to 177°C		Caterpillar 2S-3230 Bearing Lubricant for ball bearings; contains Polyurea thickener; for extremely low temperatures use NLGI No. 1 Grade or NLGI No. 0 Grade

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

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Adjustments for Generators in Parallel Operation adjustment

Connect current transformer to S1 and S2 of J2.
Set P1 quadrature droop to center.
Apply rated load; voltage should drop 2 to 3%.
Set no-load voltages identical for all generators.
Connect generators in parallel and adjust speed for 0 kW exchange.
Minimize circulating currents with P2 or Rhe.
Apply available load; equalize kW by altering speed.
Alter P1 to equalize currents.

Adjustments for Stand-alone Generators (R448) adjustment

Tools: Analog voltmeter, Voltmeter 300-500 VAC or 1000 VAC

Turn remote adjustment potentiometer to center.
Connect analog voltmeter 100 VDC to E+ and E-.
Connect voltmeter 300-500 VAC or 1000 VAC to generator output.
Set ST3 wire for desired frequency.
Turn P2 full counterclockwise.
Turn P4 full clockwise.
Turn stability P3 counterclockwise about 1/3.
Start engine and set 48 Hz for 50 Hz or 58 Hz for 60 Hz.
Adjust output voltage with P2.
Check LAM operation, ST5 closed.
Turn P4 slowly counterclockwise until voltage drop.
Vary frequency around 48 or 58 Hz and check voltage.

R448 Adjustment for Maximum Excitation adjustment

Tools: 10 Amp DC ammeter

Disconnect power supply wires X1, X2, Z1, Z2.
Disconnect sensing leads 0V, 110V, 220V, 380V.
Connect 200V-240V main power supply to X1 and X2.
Install 10 Amp DC ammeter in series with exciter field.
Turn P5 full counterclockwise and activate power supply.
Turn P2 clockwise until stable current.
Switch power off then on. Turn P5 to required maximum current.
Maximum current must not exceed 10 Amperes.

VR3 Regulator Adjustment Procedure adjustment

⚠ The VR3 regulator is protected by a fuse(s) and a solid-state overcurrent protection. If a fuse becomes open, contact a Caterpillar dealer.

Remove the access panel of the generator.
Loosen the locknut on the voltage droop potentiometer (1).
Remove the protective screw from the voltage level potentiometer (2) and from the voltage gain potentiometer (3).
Turn the voltage droop potentiometer (1) counterclockwise to zero droop. Tighten the locknut.
Turn the voltage gain potentiometer (3) counterclockwise to zero, then to about 1/4 of full range of clockwise travel.
Perform required maintenance on the engine before you start the engine.
Start the engine and allow the engine to warm up.
Increase engine speed to full governed rated speed (high idle).
Set the no-load voltage with the voltage level potentiometer (2) or the voltage adjust rheostat.
Close the load circuit breaker and apply full load gradually. Adjust governor control to nameplate frequency or rated speed.
If the voltmeter reading increases above no-load voltage, turn the voltage gain potentiometer counterclockwise. If it decreases, turn it clockwise.
Remove the load. If necessary, adjust the voltage level potentiometer (2) to obtain desired voltage.
Apply the load. Repeat Steps 10 through 12 until the voltage at no load equals the voltage at full load.
Tighten the locknuts. Install the protective screws and the access panel of the generator.

Generator Set Functional Test diagnostic

⚠ Do not exceed half rated speed

⚠ Do not allow output to exceed nameplate rating

Tools: Digital Multimeter, 12 VDC Battery

Disconnect wires F1 and F2 from voltage regulator
Disconnect generator load
Connect 12 VDC battery to wires F1+ and F2-
Operate generator at half rated speed
Measure AC voltage across terminals T1-T2, T1-T3, T2-T3
Record voltages at half speed, then at ±10% speed variations
Verify minimum 85 VAC output at half speed
Verify speed changes produce proportional voltage changes

Insulation - Test diagnostic

⚠ Electrocution hazard

Tools: 142-5055 Insulation Testing Gp, 9U-6003 Insulation Testing Gp

Take generator out of service.
Visually inspect for moisture; dry if present.
Discharge winding capacitance.
Isolate stator windings.
Connect insulation tester RED lead to ground.
Connect BLACK lead to wye point.
Set voltage to 500 V for 600 V or less, 1000 V for more than 600 V.
Apply voltage and observe readings at 30 and 60 seconds.
Record 60 second reading, temperature, humidity.
Remove voltage and evaluate reading.

Rotating Rectifier - Test diagnostic

⚠ High voltage hazard

Tools: 12 volt battery, Rheostat 50 Ohms 300 Watts, Diode, Diode bridge, Variable power supply

Stop generator set and disconnect AVR wires.
Make separate excitation assembly with 12 V battery or variable DC supply.
Connect 12 V battery in series with 50 Ohm 300 Watt rheostat and diode.
Or connect variable power supply and diode bridge.
Operate generator at rated speed.
Gradually increase exciter field current.
Measure output voltage and current at no load.
Generator is proper if output voltage is rated and balanced within one percent.

Rotating Rectifier Block Diode Test diagnostic

⚠ Shorted diode can damage exciter rotor

Tools: Digital Multimeter 6V-7070

Set digital multimeter to diode range and remove all leads
Test forward bias on each diode (black to positive, red to AC terminals)
Verify readings between 0.4 and 1.0
Test reverse bias (red to positive, black to AC terminals)
Verify overload (OL) readings on reverse bias
Replace rectifier block if any reading is outside specifications

Varistor - Test diagnostic

Tools: Ohmmeter, Test Light

Using an ohmmeter, place the ohmmeter across the varistor. The resistance should be a minimum of 15000 ohms.
Disconnect either lead of the varistor (CR7).
Place the test light across the varistor.
Observe the results. The lamp should not light.
Reverse the test light.
Observe the results. The lamp should not light.
If the test light illuminates in either direction, there is a short in the varistor. Replace any faulty varistors with comparable operating characteristics.

Winding Resistance Measurement diagnostic

⚠ Temperature affects resistance; test at room temperature only

⚠ Winding damage if outside specifications

Tools: Digital Multimeter, Milliohmmeter (Wheatstone Bridge)

Disconnect winding from other components before measuring
Measure armature windings with milliohmmeter (L2, L4, L5)
Measure field windings with multimeter (L1, L3)
Test at room temperature only
Compare measurements to specification values
Verify no continuity between windings or between winding and ground

Lead to Lead Connection installation

Tools: Varnished cambric tape 5N-4685, Vinyl plastic tape 5N-4686, Cable straps

Fasten leads using flat plated washer under bolt and nut
Apply two layers of varnished cambric high voltage tape
Overlap tape 50% of width while wrapping
Extend tape 25 mm onto wire insulation on each side
Apply two layers of vinyl plastic tape over cambric tape
Extend vinyl tape 51 mm onto wire insulation on each side
Group all phase leads and secure with cable straps

Leads to Terminal Strip Connection installation

Tools: Flat plated washers, Cable straps

When multiple leads attach to bus bar, place on alternate sides
Use flat plated washers under bolt head and nut
Group all generator phase leads together after connection
Tie phase leads together with cable straps
Maintain minimum 25 mm clearance between phase-to-phase connections

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
	3	Delta - 6 lead	6	Winding pitch must be two-thirds or the generator must be derated.
	3	Wye - 10 lead (high voltage)	10	Illustration 13. Only used on 3306B generator sets and 3406C generator sets. Terminal T0 is the neutral lead.
	3	Wye - 10 lead (low voltage)	10	Only used on 3306B and 3406C generator sets. Terminal T0 is the neutral lead.
	3	Wye - 12 lead (high voltage)	12	Terminals T10, T11, and T12 become neutral connections when tied together.
	3	Wye - 12 lead (low voltage)	12	Terminals T10, T11, and T12 become neutral connections when tied together.
	3	Wye - 4 lead	4	Only used on 3306B generator sets and 3406C generator sets. Terminal T0 is the neutral lead.
	3	Wye - 6 lead	6	Terminals T4, T5, and T6 become neutral connections when the terminals are tied together.
190-220 (50 Hz), 190-240 (60 Hz)	3	Wiring Code A	12 wire	Winding 6; 5000/6100/7000 12 wire factory connection
240	3	Delta - 12 lead	12	Terminals T6 and T9 become the neutral connections when tied together and grounded. T2 and T10 connection is the high phase. 240 V, 60 Hz, three-phase: 208 Volts between the high phase and neutral; 240 Volts between either of the low phases and neutral.
380-415 (50 Hz), 380-480 (60 Hz)	3	Wiring Code D	12 wire	Winding 6; 5000 12 wire factory connection
480	3	Parallel Wye	12 lead	Typical high voltage connection
480	3	Series Wye	12 lead	Typical high voltage connection
480	3	Wye	6 lead	Typical Wye Configuration
58% of three-phase connected voltage	1	Wye	any phase lead and neutral	Single-phase from three-phase generator
600	3	Wiring Code D	12 wire	Winding 9; R448 voltage sensing and transformer
Four Lead Wye	Three-phase	T1/T2/T3 to loads, T0 to neutral	T1, T2, T3, T0	Regulator leads 22, 24, 20 from T1, T2, T3 respectively
Six Lead Delta	Three-phase	T1/T6, T2/T4, T3/T5 series loop connections	T1, T2, T3, T4, T5, T6	Delta configuration
Six Lead Wye	Three-phase	T1/T2/T3 to loads, T4/T5/T6 to neutral	T1, T2, T3, T4, T5, T6	Regulator sensing from T1, T2, T3
Ten Lead Wye High Voltage	Three-phase	T1/T2/T3 to loads with T4/T7, T5/T8, T6/T9 series connections	T1, T2, T3, T4, T5, T6, T7, T8, T9, T0	High voltage configuration
Ten Lead Wye Low Voltage	Three-phase	T1/T7, T2/T8, T3/T9 parallel connections	T1, T2, T3, T4, T5, T6, T7, T8, T9, T0	Low voltage configuration
Twelve Lead Delta	Three-phase	T1/T12, T2/T10, T3/T11 series loops with jumpers	T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12	Delta configuration with 12 leads
Twelve Lead Wye High Voltage	Three-phase	T1/T2/T3 to loads with series connections	T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12	High voltage configuration with 12 leads
Twelve Lead Wye Low Voltage	Three-phase	T1/T7, T2/T8, T3/T9 parallel connections	T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12	Low voltage configuration with 12 leads

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Parts cataloged across the Caterpillar 3512C family

Part #	Description	Category
1440725	Connecting rod	Service part / kit

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Also used in

Caterpillar 784B — Dump Truck
Caterpillar 785B — Dump Truck
Caterpillar 785D — Haul Truck

Other equipment known to use this engine, via filter-application cross-reference — useful for sourcing parts even when your exact machine isn't listed elsewhere on this page.

Common questions

What is the displacement of the Caterpillar 3512C ATAAC?

The Caterpillar 3512C ATAAC has a displacement of 51.8 liters with 12 cylinders.

Which generators use the Caterpillar 3512C ATAAC engine?

The Caterpillar 3512C ATAAC powers 1 generator set(s), including Caterpillar SR4B.

What is a common problem with the Caterpillar 3512C ATAAC engine?

A commonly reported issue on generators using the Caterpillar 3512C ATAAC is: When the engine oil pressure is increased beyond the low oil pressure setpoint, the GSC will inform the governor that the engine speed should be increased from IDLE to RATED rpm..

Code	Name	Meaning
01-05	Injector Cylinder 1 Open Circuit	Injector Cylinder 1 Open Circuit
01-06	Injector Cylinder 1 Short	Injector Cylinder 1 Short
02-06	Injector Cylinder 2 Short	Injector Cylinder 2 Short
03-05	Injector Cylinder 3 Open Circuit	Injector Cylinder 3 Open Circuit
04-05	Injector Cylinder 4 Open Circuit	Injector Cylinder 4 Open Circuit
04-06	Injector Cylinder 4 Short	Injector Cylinder 4 Short
05-06	Injector Cylinder 5 Short	Injector Cylinder 5 Short
06-05	Injector Cylinder 6 Open Circuit	Injector Cylinder 6 Open Circuit
91-08	Throttle Position Signal Abnormal	Throttle Position Signal Abnormal
100-03	Engine Oil Pressure Open/Short to +Batt	Engine Oil Pressure Open/Short to +Batt
100-04	Engine Oil Pressure Short To Ground	Engine Oil Pressure Short To Ground
100-13	Engine Oil Pressure Calibration Required	Engine Oil Pressure Calibration Required
110-04	Engine Coolant Temperature Short To Ground	Engine Coolant Temperature Short To Ground
168-00	System Voltage High	System Voltage High
168-01	System Voltage Low	System Voltage Low
168-02	System Voltage Intermittent	System Voltage Intermittent
172-03	Intake Manifold Air Temp Open/Short To +Batt	Intake Manifold Air Temp Open/Short To +Batt
172-04	Intake Manifold Air Temp Short To Ground	Intake Manifold Air Temp Short To Ground
174-03	Fuel Temperature Open/Short To +Batt	Fuel Temperature Open/Short To +Batt
174-04	Fuel Temperature Short To Ground	Fuel Temperature Short To Ground
175-03	Engine Oil Temperature Open/Short To +Batt	Engine Oil Temperature Open/Short To +Batt
175-04	Engine Oil Temperature Short To Ground	Engine Oil Temperature Short To Ground
190-08	Engine Speed Signal Abnormal (Top Speed Timing Sensor)	Engine Speed Signal Abnormal (Top Speed Timing Sensor)
248-09	CAT Data Link Communications	CAT Data Link Communications
253-02	Personality Module Mismatch	Personality Module Mismatch
254-12	Electronic Control Module Error	Electronic Control Module Error
261-13	Engine Timing Calibration Required	Engine Timing Calibration Required
262-03	5 Volt Sensor Supply Short To +Batt	5 Volt Sensor Supply Short To +Batt
262-04	5 Volt Sensor Supply Short To Ground	5 Volt Sensor Supply Short To Ground
263-03	Digital Sensor Supply Short To +Batt	Digital Sensor Supply Short To +Batt
263-04	Digital Sensor Supply Short To Ground	Digital Sensor Supply Short To Ground
268-02	Check Programmable Parameters	Check Programmable Parameters
273-00	Turbo Outlet Pressure Above Normal	Turbo Outlet Pressure Above Normal
273-03	Turbo Outlet Pressure Open/Short To +Batt	Turbo Outlet Pressure Open/Short To +Batt
273-04	Turbo Outlet Pressure Short To Ground	Turbo Outlet Pressure Short To Ground
273-13	Turbo Outlet Pressure Calibration Required	Turbo Outlet Pressure Calibration Required
274-03	Atmospheric Pressure Open/Short To +Batt	Atmospheric Pressure Open/Short To +Batt
274-04	Atmospheric Pressure Short To Ground	Atmospheric Pressure Short To Ground
274-13	Atmospheric Pressure Calibration Required	Atmospheric Pressure Calibration Required
336-02	Incorrect ECS Switch Inputs	Incorrect ECS Switch Inputs
337-02	Incorrect Remote E-Stop Switch Inputs	Incorrect Remote E-Stop Switch Inputs
342-02	Loss Of Secondary Engine Speed Signal (Bottom Speed/Timing Sensor)	Loss Of Secondary Engine Speed Signal (Bottom Speed/Timing Sensor)
342-08	Secondary Engine Speed Signal Abnormal (Bottom Speed/Timing Sensor)	Secondary Engine Speed Signal Abnormal (Bottom Speed/Timing Sensor)
444-05	Start Relay Open Circuit	Start Relay Open Circuit
444-06	Start Relay Short To Ground	Start Relay Short To Ground
446-05	Air Shut-off Relay Open	Air Shut-off Relay Open
446-06	Air Shut-off Relay Short	Air Shut-off Relay Short
460-03	Filtered Fuel Pressure Open/Short To +Batt	Filtered Fuel Pressure Open/Short To +Batt
460-04	Filtered Fuel Pressure Short To Ground	Filtered Fuel Pressure Short To Ground
460-13	Filtered Fuel Pressure Calibration Required	Filtered Fuel Pressure Calibration Required
535-08	Exhaust Temperature Sensor Noisy Signal	Exhaust Temperature Sensor Noisy Signal
545-05	Ether Start Relay Open/Short To +Batt	Ether Start Relay Open/Short To +Batt
545-06	Ether Start Relay Short To Ground	Ether Start Relay Short To Ground
1490-02	Loss Of Engine Speed Signal (Top Speed Timing Sensor)	Loss Of Engine Speed Signal (Top Speed Timing Sensor)