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Caterpillar 3412C Engine

Name: Caterpillar 3412C Engine
Brand: Caterpillar

The Caterpillar 3412C is a 27 L 12-cylinder ta engine rated at 1800 rpm, producing up to 651 kW. It powers generator sets from Caterpillar, including the 3412C Generator Set, 3412C Generator Set DJN1-Up and 3412C Generator Set TGC1-Up. It holds 139 L (36.7 gal) of oil and 58 L (15.3 gal) of coolant.

Also known as: Caterpillar 3412C

Part of the Caterpillar 3412C engine family — 3 variants share parts & fitment.

27.0 L

Displacement

Cylinders

1800 rpm

Rated speed

651 kW

Gross power

On this pageService parts Specs Generator sets Maintenance Filter cross-reference FAQ Service intervals Torque & specs Fluids Procedures Wiring

Service parts for the 3412C

The cheapest captured merchant offer per filter — see the full cross-reference below for every OEM/aftermarket option.

Air intake

1 required

612506Air filter$66.97PartsGeek

Fuel system

2 required

3089679Fuel filter (primary)$16.89eBay

3089679Fuel filter (secondary)$16.89eBay

Oil system

1 required

2P4005Oil filter$23.97PartsGeek

Cooling system

1 required

9Y1022Coolant filter$20.00eBay

Prices captured from merchant listings; some links are affiliate links. Verify against your serial number before ordering.

Engine specifications

Oil capacity	139.0 L
Coolant capacity	58.0 L
Displacement	27.0 L
Cylinders	12
Aspiration	TA
Rated speed	1800 rpm
Gross power	651 kW

Generator sets powered by this engine

Caterpillar 3412CCaterpillar 3412C Generator SetCaterpillar 3412C Generator Set DJN1-UpCaterpillar 3412C Generator Set TGC1-Up

How to read your Caterpillar engine serial & model number →

Troubleshooting

Fault codes

Code	Meaning	Remedy
i01226491	Engine overspeed	Stop the engine by shutting off the fuel supply to the engine and/or shutting off the air supply to the engine.
21	Fault shutdown
22	Fault alarm
null	Increased coolant temperature

Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.

Common problems

Fault shutdown 21
Fault alarm 22
Engine overspeed i01226491
Fix: Stop the engine by shutting off the fuel supply to the engine and/or shutting off the air supply to the engine.
Increased coolant temperature null
Smoke emission
Fix: Each fuel injection nozzle must be isolated one at a time in order to determine the malfunctioning fuel injection nozzle. 1. Start the engine. 2. Loosen each fuel line nut one at a time at the fuel injection pump. A cloth or similar material must be used in order to prevent fuel from spraying on the hot exhaust components. Tighten each nut before loosening the next nut. 3. A defective fuel injection nozzle may be identified when a fuel line nut is loosened and the following conditions are present: • The exhaust smoke is partially eliminated or the exhaust smoke is completely eliminated. • Engine performance is not affected. A fuel injection nozzle that is suspected of being defective should be removed. A new fuel injection nozzle should be installed in the cylinder
Engine knock
Fix: Each fuel injection nozzle must be isolated one at a time in order to determine the malfunctioning fuel injection nozzle. 1. Start the engine. 2. Loosen each fuel line nut one at a time at the fuel injection pump. A cloth or similar material must be used in order to prevent fuel from spraying on the hot exhaust components. Tighten each nut before loosening the next nut. 3. A defective fuel injection nozzle may be identified when a fuel line nut is loosened and the following conditions are present: • The exhaust smoke is partially eliminated or the exhaust smoke is completely eliminated. • Engine performance is not affected. A fuel injection nozzle that is suspected of being defective should be removed. A new fuel injection nozzle should be installed in the cylinder
Abnormal engine operation
Fix: Each fuel injection nozzle must be isolated one at a time in order to determine the malfunctioning fuel injection nozzle. 1. Start the engine. 2. Loosen each fuel line nut one at a time at the fuel injection pump. A cloth or similar material must be used in order to prevent fuel from spraying on the hot exhaust components. Tighten each nut before loosening the next nut. 3. A defective fuel injection nozzle may be identified when a fuel line nut is loosened and the following conditions are present: • The exhaust smoke is partially eliminated or the exhaust smoke is completely eliminated. • Engine performance is not affected. A fuel injection nozzle that is suspected of being defective should be removed. A new fuel injection nozzle should be installed in the cylinder
Yellow fault alarm indicator (26) flashes
Fix: Refer to the Systems Operation, Testing and Adjusting, RENR2484, “Electronic Modular Control Panel II + (EMCP II+)” for descriptions of the fault codes
Red fault shutdown indicator (25) flashes
Fix: Refer to the Systems Operation, Testing and Adjusting, RENR2484, “Electronic Modular Control Panel II + (EMCP II+)” for descriptions of the fault codes
Dedicated shutdown faults: low oil pressure
Cause: Engine oil pressure drops below setpoints programmed into GSC+
Fix: Correct the fault and engine is not allowed to start until the fault is corrected
Dedicated shutdown faults: high water temperature
Cause: Engine coolant temperature rises above setpoint programmed into GSC+
Fix: Correct the fault and engine is not allowed to start until the fault is corrected
Dedicated shutdown faults: engine overspeed
Cause: Engine speed exceeds setpoint programmed into GSC+
Fix: Correct the fault and engine is not allowed to start until the fault is corrected
Dedicated shutdown faults: emergency stop
Cause: Operator presses Emergency Stop Push Button (ESPB) on front panel
Fix: Correct the condition and engine is not allowed to start until the condition is corrected

Compiled from service & troubleshooting documentation across every generator set that uses the Caterpillar 3412C.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	Dual Element		612506		Amazon eBay $100.00 PartsGeek $66.97
Fuel filter	Primary Filter (Water Separator)		3089679	250 hr	Amazon eBay $16.89 PartsGeek $25.97 FridayParts $58.99
Oil filter			2P4005	250 hr	Amazon eBay $32.99 PartsGeek $23.97 KuduParts $39.00
Battery	Maintain electrolyte level to FULL mark; use distilled water		—	250 hr
Belt	Deflect 13 to 19 mm (0.50 to 0.75 inch) with 110 N (25 lb) force		—	250 hr
Coolant	DEAC or ELC	58.0	—	6000 hr
Coolant filter	Cat ELC Extender added once		9Y1022	6000 hr	eBay $20.00
Oil		139.0	—	250 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Sea Water Strainer	Clean	50 hr		When required and every 3800 L (1000 US gal) of fuel or 50 service hours
Zinc Rods	Inspect	50 hr		When required and every 3800 L (1000 US gal) of fuel or 50 service hours; replace when deteriorated
Alternator Belt	Inspect	250 hr	12 mo	Inspect/adjust/replace; every 12 750 L (3375 US gal) of fuel or 250 h or yearly (8RG1-Up); every 19 000 L (5000 US gal) or 250 h or yearly (REA1-Up, 3JK1-Up, 7BL1-Up)
Alternator and Fan Belts	Replace	250 hr		Inspect/Adjust/Replace - Every 19 000 L (5000 US gal) of Fuel or 250 Service Hours
Battery Electrolyte Level	Check	250 hr	12 mo	Every 19 000 L (5000 US gal) of Fuel or 250 Service Hours
Cooling System Coolant Sample (Level 1)	Test	250 hr		Obtain - Every 250 Service Hours
Cooling System Supplemental Coolant Additive (SCA)	Test	250 hr	12 mo	Test/Add; 8RG1-Up: 12 750 L (3375 US gal) or 250 h or yearly; other S/N: 19 000 L (5000 US gal) or 250 h or yearly
Engine Air Cleaner Element	Clean	250 hr	12 mo	Clean/Replace; 8RG1-Up: 12 750 L (3375 US gal) or 250 h or yearly; other S/N: 19 000 L (5000 US gal) or 250 h or yearly
Engine Crankcase Breather	Clean	250 hr	12 mo	Every 19 000 L (5000 US gal) of Fuel or 250 Service Hours
Engine Oil Sample	Other	250 hr	12 mo	Obtain S·O·S oil sample; 8RG1-Up: 12 750 L (3375 US gal) or 250 h or yearly; other S/N: 19 000 L (5000 US gal) or 250 h or yearly
Engine Oil and Filter	Change	250 hr	12 mo	8RG1-Up: 12 750 L (3375 US gal) or 250 h or yearly; other S/N: 19 000 L (5000 US gal) or 250 h or yearly
Engine Protective Devices	Check	250 hr		Every 19 000 L (5000 US gal) of Fuel or 250 Service Hours
Fuel System Primary Filter	Clean	250 hr	12 mo	Clean/Replace; 8RG1-Up: 12 750 L (3375 US gal) or 250 h or yearly; other S/N: 19 000 L (5000 US gal) or 250 h or yearly
Fuel System Secondary Filter	Replace	250 hr	12 mo	8RG1-Up: 12 750 L (3375 US gal) or 250 h or yearly; other S/N: 19 000 L (5000 US gal) or 250 h or yearly
Fuel Tank Water and Sediment	Drain	250 hr	12 mo	8RG1-Up: 12 750 L (3375 US gal) or 250 h or yearly; other S/N: 19 000 L (5000 US gal) or 250 h or yearly
Hoses and Clamps	Inspect	250 hr	12 mo	Inspect/Replace; 8RG1-Up: 12 750 L (3375 US gal) or 250 h or yearly; other S/N: 19 000 L (5000 US gal) or 250 h or yearly
Magnetic Pickups	Clean	250 hr		First service — Clean/Inspect - First 19 000 L (5000 US gal) of Fuel or 250 Service Hours
Aftercooler Core	Clean	1000 hr		When required; also every 76 000 L (20 000 US gal) of fuel or 1000 service hours
Heat Exchanger	Inspect	1000 hr		When required; also every 76 000 L (20 000 US gal) of fuel or 1000 service hours
Engine Speed/Timing Sensors	Check	1500 hr		Check/Clean/Calibrate; 76 500 L (20 250 US gal) of fuel or 1500 h (8RG1-Up); 114 000 L (30 000 US gal) or 1500 h (REA1-Up, 3JK1-Up, 7BL1-Up)
Engine Valve Lash	Adjust	1500 hr		First service — Inspect/Adjust; 76 500 L (20 250 US gal) of fuel or 1500 h (8RG1-Up); 114 000 L (30 000 US gal) or 1500 h (other S/N)
Engine Valve Rotators	Inspect	1500 hr		76 500 L (20 250 US gal) of fuel or 1500 h (8RG1-Up); 114 000 L (30 000 US gal) or 1500 h (other S/N)
Cooling System Coolant Sample (Level 2)	Test	2000 hr	12 mo	First service — Obtain - Every 2000 Service Hours or 1 Year
Engine	Clean	2000 hr	6 mo	Every 2000 Service Hours or 6 Months
Fuel System	Other	2000 hr	6 mo	Prime - Every 2000 Service Hours or 6 Months
Generator	Other	2000 hr	6 mo	Dry - Every 2000 Service Hours or 6 Months
Generator Lead (Round Cable)	Check	2000 hr		Every 2000 Service Hours
Generator Set	Test	2000 hr	6 mo	Every 2000 Service Hours or 6 Months
Rotating Rectifier	Test	2000 hr	6 mo	Every 2000 Service Hours or 6 Months
Severe Service Application	Check	2000 hr	6 mo	Every 2000 Service Hours or 6 Months
Alternator	Inspect	3000 hr		153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (REA1-Up, 3JK1-Up, 7BL1-Up)
Auxiliary Water Pump	Inspect	3000 hr		153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (other S/N)
Cooling System Coolant (DEAC)	Change	3000 hr		153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (other S/N)
Cooling System Water Temperature Regulator	Replace	3000 hr		153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (other S/N)
Crankshaft Vibration Damper	Inspect	3000 hr		153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (other S/N)
Engine Mounts	Inspect	3000 hr		153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (other S/N)
Fuel Injection Nozzles	Test	3000 hr		Test/Exchange; 153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (other S/N)
Starting Motor	Inspect	3000 hr		153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (other S/N)
Turbocharger	Inspect	3000 hr		153 500 L (40 500 US gal) of fuel or 3000 h (8RG1-Up); 228 000 L (60 000 US gal) or 3000 h (other S/N)
Cooling System Coolant Extender (ELC)	Other	6000 hr	36 mo	Add; every 6000 service hours or 3 years

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 (engines without recovery tank)	within 13	mm	0.5 inch
Clearance	Water pump leakage considered normal as engine cools	small amount		water pump seal is lubricated by coolant in the cooling system
Other	Alternator belt deflection	13 to 19	mm	110 N (25 lb) of force applied midway between the pulleys; 0.50 to 0.75 inch
Other	Belt tension deflection	0.50 to 0.75	inch	110 N (25 lb) force midway between pulleys
Other	Belt tension deflection	13 to 19	mm	110 N (25 lb) force midway between pulleys
Other	Caterpillar Fast Acting Cooling System Cleaner concentration	0.5	L per 15 L	1 pint per 4 US gal of cooling system capacity
Other	Chlorine content limit for heat exchanger cleaning water	more than 300	ppm	water containing more than 300 ppm of chlorine should not be used
Other	Coolant level below filler pipe bottom	13	mm
Other	Cooling system fill rate	no faster than 19	L per minute	5 US gal per minute to avoid air locks
Other	Cooling system fill rate (maximum)	19	L per minute	to avoid air locks
Other	Engine valve rotator operation	should turn slightly when valves close
Other	Generator excitation PMG short circuit capability	3 X In for 10 seconds
Other	High idle speed for droop governors	approximately 2% to 5%	above full load speed	governors equipped with droop
Other	Paper air cleaner element reuse limit	up to six	times	replace at least one time per year regardless of number of cleanings
Other	Plate type heat exchanger cleaner concentration	maximum 4	percent by weight	cleaning solution temperature less than 60°C (140°F)
Other	Solvent contact time with heat exchanger gaskets	not more than half an hour		natural rubber, butyl rubber and EPDM gaskets swell in these solvents
Other	Speed droop values commonly used	3% and 0%	%
Other	Supplemental Coolant Additive (SCA) concentration, coolant and SCA	do not exceed six	percent
Other	Supplemental Coolant Additive (SCA) concentration, water and SCA	do not exceed eight	percent
Other	Vibration damper inspection	dented, cracked, leaking, bent or discolored damper must be replaced
Other	Voltage droop for 0.8 power factor load	approximately 5	%	loads with a power factor of 0.8
Pressure	Auxiliary water pump differential pressure requiring component inspection	more than 103	kPa	15 psi
Pressure	Coolant system pressure test - use 9S-8140 Pressurizing Pump	9S-8140
Pressure	Engine oil pressure at low idle	186 to 344	kPa	low idle speed
Pressure	Fuel pressure (below which engine will not operate properly)	160	kPa
Pressure	Maximum air pressure at nozzle for cleaning	less than 205	kPa	30 psi
Pressure	Maximum air pressure for cleaning	205	kPa	deadheaded nozzle with chip guarding
Pressure	Maximum air pressure for cleaning purposes	205	kPa (30 psi)	must be below
Pressure	Maximum pressure of filtered, dry air for cleaning paper air cleaner elements	207	kPa	30 psi
Pressure	Maximum water pressure for cleaning	275	kPa
Pressure	Maximum water pressure for cleaning purposes	275	kPa (40 psi)	must be below
Pressure	Maximum water pressure for rinsing air cleaner element	275	kPa	40 psi; do not use a spray nozzle
Pressure	Minimum recommended oil pressure	103	kPa	600 rpm
Pressure	Minimum recommended oil pressure	15	psi	600 rpm
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
Pressure	Primary filter/water separator change pressure	50 to 70	kPa	15 to 20 inches Hg
Pressure	Typical engine oil pressure at rated rpm with SAE10W30 (turbocharged)	275 to 606	kPa	rated rpm
Pressure	Typical engine oil pressure at rated rpm with SAE10W30 (turbocharged)	40 to 88	psi	rated rpm
Resistance	Exciter Armature (Rotor) (L2) resistance	less than 0.1	ohm	room temperature
Resistance	Exciter Field (Stator) (L1) resistance	3.0 to 6.0	ohms	room temperature
Resistance	Insulation resistance minimum (contaminated generator)	1	megohm
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	Pilot Exciter Armature (L5) resistance	less than 0.1	ohm	room temperature
Resistance	Varistor (CR7) resistance	minimum 15000	ohms
Speed	Actual RPM of overspeed (1500 full load rpm)	1770	rpm	multiply full load RPM by 1.18
Speed	Actual RPM of overspeed (1800 full load rpm)	2124	rpm	multiply full load RPM by 1.18
Speed	Engine speed for purging air from engine block cavities during coolant fill	1500	rpm	run one minute at 1500 rpm; low idle to increase
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	Generator set functional test minimum phase voltage	85	VAC	half rated speed
Speed	Low idle (50 Hz units)	80	percent of full load speed
Speed	Low idle (50 Hz units)	approximately 80	% of full load speed	50 Hz units
Speed	Low idle (60 Hz units)	66	percent of full load speed
Speed	Low idle (60 Hz units)	approximately 66	% of full load speed	60 Hz units
Speed	Magnetic pickup crank termination	400	rpm	starter pinion disengagement
Speed	Overspeed switch setpoint	118	percent of rated engine speed
Speed	Test RPM for overspeed (1500 full load rpm)	1328	rpm	multiply full load RPM by 0.885
Speed	Test RPM for overspeed (1800 full load rpm)	1593	rpm	multiply full load RPM by 0.885

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)	Conventional heavy-duty coolant/antifreeze; commercial long life coolants meeting Caterpillar EC-1			Level 1 coolant sample every 250 hours; Level 2 yearly; DEAC change every 3000 service hours
Coolant	Cat DEAC Diesel Engine Antifreeze/Coolant	ASTM D4985 or ASTM D5345		58.0 L	Acceptable; 1:1 mixture of water and glycol; service life three years; does not require SCA at initial fill
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)				Does not require frequent SCA additions; Level 1 sample optional, Level 2 yearly; ELC change every 12 000 service hours or 6 years
Coolant	Cat ELC Extended Life Coolant	Caterpillar EC-1		58.0 L	Preferred; 1:1 mixture of water and glycol; service life six years; add ELC Extender once
Coolant	Cat ELC Extender				Add every 6000 service hours or 3 years according to requirements for cooling system capacity
Coolant	Cat NGEC				Natural Gas; 16,000 Service Hours or Three Years; use interval that occurs first
Coolant	Caterpillar SCA and Water				For stationary applications not requiring boiling/freezing protection; minimum six percent to maximum eight percent SCA concentration; service life two years
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	Cat DEO Multigrade API CH-4/API CG-4	-40°C to 10°C
Engine oil	SAE 0W-30	Cat DEO Multigrade API CH-4/API CG-4	-40°C to 30°C
Engine oil	SAE 0W-40	Cat DEO Multigrade API CH-4/API CG-4	-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	Cat DEO Multigrade API CH-4/API CG-4	-30°C to 30°C
Engine oil	SAE 5W-40	Cat DEO Multigrade API CH-4/API CG-4	-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	Cat DEO Multigrade API CH-4/API CG-4	-18°C to 40°C
Engine oil	Cat DEO SAE 15W-40		-9°C to 50°C		Engine Crankcase; Industrial Engines
Engine oil	SAE 15W-40	Cat DEO Multigrade API CH-4/API CG-4	-9°C to 50°C
Fuel		LCV = 42700 kJ/kg			MaK technical data; without engine-driven pumps, tolerance 5%
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	No. 1-D or No. 2-D	ASTM D975			Use No. 1 diesel fuel or a blend of No. 1 and No. 2 for cold-weather operation; No. 2 is most commonly used
Grease	Cat Generator Set Grease				Part Number 108-8611
Grease	High Speed Ball Bearing Grease				Fan drive bearing grease fitting
Grease	Multipurpose Grease	1P-0808			Fuel control linkage lubrication
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.

Procedures

Alternator Belt - Inspect/Adjust/Replace adjustment

⚠ Replace belts for multiple groove pulleys in matched sets.

Tools: Belt tension gauge (110 N / 25 lb force)

Remove the belt guard.
Loosen mounting bolt (2) and adjusting nuts (1).
Turn adjusting nuts to increase or decrease belt tension.
Check deflection is 13 to 19 mm with 110 N applied midway.
Tighten the adjusting nuts; tighten the mounting bolt.
Reinstall the belt guard.
Check adjustment again after 30 minutes at rated rpm if new belts.

Engine Valve Lash - Inspect/Adjust adjustment

⚠ Hot engine components can cause burns.

⚠ Only qualified service personnel should perform this maintenance.

Ensure the engine cannot be started; do not use the starting motor to turn the flywheel.
Ensure the engine is stopped and allow valves to cool.
Refer to the Systems Operation/Testing and Adjusting Manual for the complete procedure.
Set inlet valve lash to 0.38 mm (0.0150 inch).
Set exhaust valve lash to 0.76 mm (0.030 inch).
Perform initial adjustment at the first scheduled oil change.

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 operate the generator set at a speed higher than one-half of the rated speed.

Tools: 6V-7070 Digital Multimeter, 12 VDC battery, Potential Transformer

Stop the generator. Connect the potential transformer's high voltage winding to generator terminals T1 and T2. Connect the voltmeter to the low voltage winding.
Disconnect wires F1+ and F2- from the voltage regulator. Disconnect the generator from the load.
Connect a 12 VDC automotive battery to wires F1+ and F2-.
Operate the generator set at half the rated speed.
Measure the AC voltage across the low voltage terminals corresponding to T1-T2, T2-T3, and T3-T1. Record the voltages.
Monitor the voltage between any two locations, then decrease the generator set speed by 10 percent and increase it by 10 percent.
The measured voltages should be nearly equal and should measure a minimum of 85 VAC.
When speed is decreased by 10 percent the voltages should decrease by 10 percent; when increased by 10 percent the voltages should increase by 10 percent.

Rotating Rectifier - Test diagnostic

Tools: 6V-7070 Digital Multimeter, 146-4080 Digital Multimeter (RS-232)

Touch the red ohmmeter lead to the rectifier terminal marked '+'.
Touch the black ohmmeter lead to terminals AC1, AC2, and AC3; the meter should indicate an open circuit or high resistance.
Touch the black ohmmeter lead to the rectifier terminal marked '+'.
Touch the red ohmmeter lead to terminals AC1, AC2, and AC3; the meter should indicate a good diode or low resistance.
Touch the black ohmmeter lead to the rectifier terminal marked '-'.
Touch the red ohmmeter lead to terminals AC1, AC2, and AC3; the meter should indicate an open circuit or high resistance.
Touch the red ohmmeter lead to the rectifier terminal marked '-'.
Touch the black ohmmeter lead to terminals AC1, AC2, and AC3; the meter should indicate a good diode or low resistance.
If the meter does not indicate the expected result, the rectifier is bad. Replace the rectifier.

Rotating Rectifier - Test (Brushless Exciter) diagnostic

Tools: 6V-7070 Digital Multimeter, 9U-7330 Multimeter, 146-4080 Digital Multimeter (RS-232), 7X-1710 Multimeter Probe Group

Remove the cover from the exciter.
Remove the nut securing the rectifier to the heat sink.
Remove the diode lead and lift the rectifier from the heat sink.
Connect ohmmeter leads across the rectifier and note reading.
Reverse the ohmmeter leads and note reading.
Low resistance one direction and high the other indicates a good rectifier.
Low resistance both directions indicates shorted rectifier.
High resistance both directions indicates open rectifier; replace faulty rectifiers.

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.

Aftercooler Core - Clean/Test maintenance

⚠ Do not use a high concentration of caustic cleaner to clean the core.

⚠ Maximum air pressure at the nozzle must be less than 205 kPa (30 psi).

Tools: Pressure air supply (maximum 205 kPa / 30 psi at nozzle)

Remove the core. Refer to the Service Manual for the procedure.
Turn the aftercooler core upside-down in order to remove debris.
Back flush the core with cleaner (1U-5490 or 174-6854 Hydrosolv).
Steam clean the core to remove residue; flush the fins.
Wash the core with hot, soapy water; rinse thoroughly with clean water.
Dry the core with compressed air in the reverse direction of normal flow.
Inspect the core for cleanliness; pressure test; repair if necessary.
Install the core. Refer to the Service Manual for the procedure.

Battery - Replace maintenance

⚠ Batteries give off combustible gases which can explode.

⚠ Removing cables with cover in place may cause battery explosion.

Turn key start switch to OFF; remove key and all electrical loads.
Turn OFF and disconnect battery charger.
Disconnect NEGATIVE - cable from NEGATIVE - battery terminal.
Disconnect POSITIVE + cable from POSITIVE + battery terminal.
Remove the used battery.
Install the new battery.
Connect cable from starting motor to POSITIVE + terminal.
Connect cable from ground plane to NEGATIVE - terminal.

Battery Disconnect Switch - Check maintenance

⚠ Never move the battery disconnect switch to OFF while the engine is operating.

With switch ON verify electrical components, hour meter and cranking function.
Turn the battery disconnect switch to the OFF position.
Verify electrical components, hour meter and cranking do not function.
Consult your Caterpillar dealer if any item continues to function.

Battery Electrolyte Level - Check maintenance

⚠ All lead-acid batteries contain sulfuric acid; wear face shield and protective clothing.

Tools: 245-5829 Coolant Battery Tester Refractometer

Remove the filler caps; maintain the electrolyte to the FULL mark.
Add distilled water if necessary; avoid artificially softened water.
Check electrolyte condition with the 245-5829 Coolant Battery Tester Refractometer.
Clean battery case with baking soda/water or ammonia/water solution; rinse.
Clean terminals and cable clamps with fine grade sandpaper.
Coat clamps and terminals with 5N-5561 Silicone Lubricant, petroleum jelly or MPGM.
Clean the battery case; keep the batteries clean.

Bearing (Ball) - Lubricating Process maintenance

Tools: Grease fitting, 8F-9866 Grease gun

Remove either the louver assembly or the rear plate from the rear of the generator housing.
Remove the top grease pipe plug and remove the lower grease pipe plug.
Install a grease fitting in the grease pipe.
Grease the shielded ball bearings with 2S-3230 Bearing Lubricant (53.28 mL (1.8 ounces) to 59.20 mL (2.0 ounces)).
Wipe off the excess grease. Remove the top grease fitting. Install the plug.
Operate the generator for one hour to allow the grease to expand and force excess grease from the cavity.
Stop the engine. Install the plug in the bottom grease pipe and wipe off the excess grease.
Install the louver assembly or install the rear plate.

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.
	three-phase	10 Lead Wye Configuration - High Voltage	Terminal T0 is the neutral lead	For 3306B and 3406C generator sets only
	three-phase	10 Lead Wye Configuration - Low Voltage	Terminal T0 is the neutral lead	For 3306B and 3406C generator sets only
	three-phase	12 Lead Delta Configuration	Terminals T6 and T9 become the neutral connection when tied together and grounded; T2 and T10 connection is the high phase
	three-phase	12 Lead Wye Configuration - High Voltage	Terminals T10, T11 and T12 become neutral connection when tied together
	three-phase	12 Lead Wye Configuration - Low Voltage	Terminals T10, T11 and T12 become neutral connection when tied together
	three-phase	4 Lead Wye Configuration	Terminal T0 is the neutral lead	For 3306B and 3406C generator sets only
	three-phase	6 Lead Delta Configuration
	three-phase	6 Lead Wye Configuration	Terminals T4, T5 and T6 become neutral connection when tied together
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.
240	three-phase	Delta Configuration (60 Hz, 12 Lead)	T6 and T9 neutral when tied together and grounded	208 Volts between high phase and neutral; 240 Volts between either low phase and neutral
480	three-phase	Wye Configuration (typical series Wye, 60 Hz, 12 Lead)	T10, T11, T12 neutral when tied	For 3406E, 3412C and 3500 series generator sets only - high voltage

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 3412C family

Part #	Description	Category
102-9720	Cleaning Kit (detergent and oil for AIRSEP air cleaner elements)	air_filter
151-7737	Air Primary	air_filter
189-0202	Air Secondary	air_filter
4N0015	Air filter outer	air_filter
9Y-3879	Air	air_filter
6T1395	Alternator	alternator
118-2018	V-belt	belt
6N6798	V-belt	belt
9L6639	V-belt	belt
3412C	Engine	engine
174-6854	Hydrosolv 100 liquid cleaner, 19 L (5 US gallon)	fluid
1U-5490	Hydrosolv 4165 liquid cleaner, 19 L (5 US gallon)	fluid
5N-5561	Silicone Lubricant	fluid
133-5673	Fuel/Water Separator	fuel_filter
1R-0749	Fuel Secondary - ADV	fuel_filter
1R0749	Filter fuel	fuel_filter
4N1151	Gasket oil pan	gasket
3T8705	Glow plug	glow_plug
3T8706	Glow plug	glow_plug
7C1068	Water pump impeller	impeller
8S-2245	Injection Cleaning Tool Group (fuel injection nozzles)	injector
1R-0716	Engine Oil	oil_filter
1R-1808	Engine Oil - ADV	oil_filter
1R1808	Filter oil	oil_filter
169-8373	Fluid Sampling Bottle	other_service
4C-9301	Coolant Conditioner Test Kit	other_service
5P-3413	Pipe Sealant for external threads of the zinc rod plug	other_service
8N1728	Connecting rod	other_service
8T-5296	Coolant Conditioner Test Kit	other_service
9S-3263	Compound for the shoulder of a new zinc rod	other_service
g00104545	Illustration 4	other_service
g00107406	Illustration 1: Safety message for the clutch located on the clutch housing (if equipped).	other_service
g00107407	Illustration 2: Safety message for rotating gears that can cause entanglement of the fingers and hands.	other_service
g00294510	Improper jumper cable connections can cause an explosion resulting in personal injury.	other_service
i01359666	Crushing Prevention and Cutting Prevention	other_service
i01372247	Mounting and Dismounting	other_service
i01372262	Illustration 4: Safety message for flammable fluids and hot surfaces.	other_service
i01480768	Burn Prevention	other_service
i01658146	Important Safety Information	other_service
i01805780	Before Starting Engine	other_service
i02345910	Do not allow unauthorized personnel on the engine or around the engine when the engine is serviced.	other_service
108-6633	Fuel pump	pump
137-1339	Water pump	pump
161-4113	Oil pump	pump
1U-5718	Vacuum Pump	pump
384-8612	Lift/transfer pump	pump
142-5867	Front seal	seal
142-5868	Rear seal	seal
4P-7610	Magnetic Pickup Group (engine speed/timing sensor in flywheel housing)	sensor

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

Aftermarket parts that fit this engine

2H-3750 FridayParts $598.56 5F-4899 FridayParts $598.56 171-2212 FridayParts $75.99 7G-7889 FridayParts $187.20 122-6585 FridayParts $123.56 261-6847 FridayParts $112.35 2W-6593 FridayParts $999.75 189-0202 eBay $60.00 FridayParts $79.99 166-1681 FridayParts $79.99 7T-2798 FridayParts $41.23 160-8178 FridayParts $218.89 379-8869 FridayParts $218.89 0R-0916 FridayParts $218.89 9Y-2988 FridayParts $40.68 212-5883 FridayParts $156.66 124-1855 FridayParts $22.23 197-9322 FridayParts $92.88 440-0257 FridayParts $109.20 7W-8003 FridayParts $1248.80 133-6350 FridayParts $1301.00 109-4367 FridayParts $179.99 261-6848 FridayParts $159.99 4N-2572 FridayParts $262.16 1R-0749 Amazon $90.99 Amazon $19.99 eBay $135.88 eBay $135.88 KuduParts $17.00 0R-9943 FridayParts $57.05 129-1351 FridayParts $57.05 4W-7021 FridayParts $52.97 0R-9797 FridayParts $52.97 9G-8010 eBay $39.00 FridayParts $16.90 6T-4949 FridayParts $58.30 170-0061 FridayParts $29.99 133-5673 Amazon $47.30 eBay $19.99 eBay $19.99 KuduParts $19.00 513-4490 Amazon eBay $23.43 PartsGeek $48.97 FridayParts $29.99 2W-4234 FridayParts $68.83 3I-1169 FridayParts $68.83 129-0375 KuduParts $22.00 4N-9680 FridayParts $28.99 931G FridayParts $28.99 5N-8757 FridayParts $359.99 318-1180 FridayParts $128.56 163-8516 FridayParts $57.79 6N-1030 FridayParts $545.30 9L-5854 FridayParts $42.88 110-2220 FridayParts $42.88 142-7072 FridayParts $42.88 142-6217 FridayParts $42.88 338-1462 FridayParts $459.99 5D-0470 FridayParts $38.99 106-3969 FridayParts $82.50 6L-8617 FridayParts $39.59 3L-2866 FridayParts $39.59 9M-0853 FridayParts $201.39 128-0317 FridayParts $75.80 174-1504 FridayParts $116.89 3T-4704 FridayParts $110.76 4W-0511 FridayParts $570.99 102-0050 Amazon eBay FridayParts $72.00 108-3190 FridayParts $69.60 4W-8471 FridayParts $197.56 TV8116 FridayParts $858.99

Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.

Filters for this engine

Air filter: Caterpillar 612506 Donaldson P532506 Wix 46589 Ac Delco A1586C
Coolant filter: Caterpillar 9Y1022 Donaldson P554073 Wix 24073 Ac Delco WF114
Fuel filter (primary): Caterpillar 3089679 Donaldson P551311 Wix 33674NP
Fuel filter (secondary): Caterpillar 3089679 Donaldson P551311 Wix 33674NP
Oil filter: Caterpillar 2P4005 Donaldson P554005 Wix 51792 Ac Delco PF879L

Cross-referenced via Donaldson + OEM/engine-maker interchange — options to verify against your serial number, not confirmed for every exact variant.

Also used in

Caterpillar 657E — Scraper
Caterpillar 992C — Loader Wheeled
Caterpillar 992D — Loader Wheeled
Caterpillar D10N — Tractor Tracked
Caterpillar D9L — Tractor Tracked
Manitowoc 4599 SERIES 4 — Dragline

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 oil capacity of the Caterpillar 3412C?

The Caterpillar 3412C engine has an oil capacity of 139.0 liters.

What is the displacement of the Caterpillar 3412C?

The Caterpillar 3412C has a displacement of 27.0 liters with 12 cylinders.

Which generators use the Caterpillar 3412C engine?

The Caterpillar 3412C powers 4 generator set(s), including Caterpillar 3412C, Caterpillar 3412C Generator Set, Caterpillar 3412C Generator Set DJN1-Up, Caterpillar 3412C Generator Set TGC1-Up.

What oil filter does the Caterpillar 3412C use?

The Caterpillar 3412C uses oil filter part numbers Caterpillar 2P4005, Donaldson P554005, Wix 51792.

What fuel filter does the Caterpillar 3412C use?

The Caterpillar 3412C uses fuel filter part numbers Caterpillar 3089679, Donaldson P551311, Wix 33674NP.

What air filter does the Caterpillar 3412C use?

The Caterpillar 3412C uses air filter part numbers Caterpillar 612506, Donaldson P532506, Wix 46589.

How often should you change the oil in the Caterpillar 3412C?

The Caterpillar 3412C oil change interval is every 250 hours.

What is a common problem with the Caterpillar 3412C engine?

A commonly reported issue on generators using the Caterpillar 3412C is: Fault shutdown.