Caterpillarengine - generator setgenerator set
Caterpillar G3412
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar G3412 is a stationary natural gas generator set designed for emergency standby and prime power applications in industrial, commercial, and healthcare facilities. Built on the G3412C 27-liter V12 spark-ignited engine platform, it delivers 350 to 512 kW of standby power at 1800 RPM. The unit typically weighs between 6,500 kg (14,330 lb) for narrow base configurations and up to 10,886 kg (24,000 lb) for sound-attenuated enclosures. Production spanned from the mid-2000s through the early 2020s, serving as the high-output successor to the G3408 and predecessor to the G3500 series in Caterpillar's gas engine lineup. Configurations include open skid, sound-attenuated, and containerized packages, with options for natural gas, biogas, or propane fuel.
Across its generations, the G3412 evolved from mechanical fuel control to the ADEM A4 electronic governor, improving air-fuel ratio precision and emissions compliance for EPA Subpart JJJJ standards. The shift to electronic control reduced maintenance complexity but increased reliance on specialized diagnostic tools. In the used and parts market, the G3412 remains highly valued for its robust V12 architecture and fuel flexibility, particularly in regions with abundant natural gas infrastructure. Its widespread adoption in critical infrastructure ensures a strong aftermarket support network for engines, alternators, and control panels, making it a cost-effective alternative to newer Tier-compliant diesel units for facilities seeking to eliminate diesel storage requirements.
Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.
Caterpillar G3412 specifications
Engine
| Model | G3412C (V12 spark-ignited natural gas engine) |
| Gross/Net Power | Standby: 512 ekW (640 kVA) @ 0.8 pf; Continuous: 423 ekW @ 0.8 pf; Prime: 375 kW (varies by configuration/series) |
| Displacement | 27 L (1,648 in³) |
| Cylinders | 12 (V12) |
| Emissions Tier | EPA 40 CFR Part 60 Subpart JJJJ (Stationary Emergency); meets most worldwide requirements down to 0.5 g/bhp-hr NOx without aftertreatment |
Weights
| Operating/Dry Weight | 9,664 lb (4,383 kg) (open configuration); 14,330 lb (6,500 kg) (dry weight, narrow base configuration) |
Dimensions
| Transport Length | 179 in (4,547 mm) (open configuration); 149.5 in (3,796 mm) (narrow base) |
| Transport Width | 88 in (2,235 mm) (open configuration); 73 in (1,854 mm) (narrow base) |
| Transport Height | 86 in (2,184 mm) (open configuration); 85.2 in (2,163 mm) (narrow base) |
Performance
| Speed/RPM | 1,500 rpm (50 Hz); 1,800 rpm (60 Hz) |
| Frequency | 50 Hz or 60 Hz |
| Voltage Options | 208V, 220V, 440V, 277/480V, 346/600V |
Service capacities (summary)
| Oil Change Interval | 250 hours |
| Coolant Change Interval | 4,000 hours |
| Air Filter Interval | 1,000 hours |
| Spark Plug Interval | 1,500 hours |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
G3412 fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) | 85 to 170 liters (22 to 45 US gal) varies by configuration/series | Cat DEO or Cat DEO-ULS meeting Cat engine crankcase fluid specification; SAE 15W-40 for most ambient ranges; SAE 10W-30 for cooler climates; Cat DEO-ULS SYN 5W-40 or Cat DEO Cold Weather 0W-40 for sustained sub-freezing starts |
| Cooling system | 60 to 76 liters (16 to 20 US gal) engine-only; 110 to 150 liters (29 to 40 US gal) with radiator or remote cooling package varies by configuration/series | Cat Extended Life Coolant (Cat ELC), premixed 50/50 with water; conventional low-silicate coolant with Cat-approved supplemental coolant additive (SCA) is an alternative |
| Fuel tank | Not documented for this exact serial range — verify with your dealer | Diesel fuel meeting Cat distillate diesel fuel specification (No. 1-D or No. 2-D per ASTM D975), minimum cetane number 40 |
| Transmission/powertrain compartments | Not applicable | Not applicable |
| Final drives | Not applicable | Not applicable |
| Hydraulic system and tank | Not applicable | Not applicable |
| Axles/differentials | Not applicable | Not applicable |
| Grease (spec only) | Not applicable | Cat Multipurpose Grease (Cat MPGM), NLGI Grade 2 for normal ambient temperatures; NLGI Grade 1 or 0 in sustained cold climates |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar G3412 maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 15,000 h |
|
Servicing the G3412 beyond the schedule
Predictive Maintenance & Fluid Analysis
Implement S.O.S fluid analysis at every 1,000-hour interval to monitor wear metals and coolant chemistry. Check SCA concentration levels during the 500-hour service to prevent liner cavitation. Monitor coolant pH and glycol content during the 2,000-hour flush to ensure corrosion inhibitors remain effective. Analyze engine oil for fuel dilution, which is critical for spark-ignited engines running on low-pressure gas. Use trend data to predict turbocharger health and bearing wear before failure occurs.
Corrective & Common Repairs
Address ignition system failures by replacing spark plugs at the strict 1,500-hour interval, regardless of condition. Inspect ignition modules and wiring harnesses for heat damage near the exhaust manifold. Replace fuel filter elements at 500 hours to prevent injector clogging from particulate contamination. Check the charge air cooler cores at 1,000 hours for debris buildup that restricts airflow and reduces power output. Verify governor linkage adjustment if engine speed fluctuates under load changes.
Overhaul & Rebuild Points
Plan for a major overhaul at approximately 15,000 hours of operation. Replace all piston rings and cylinder liners to restore compression and oil control. Recondition or replace crankshaft bearings based on wear metal analysis results. Inspect cylinder heads for warpage and replace valves if seat wear exceeds limits. Re-torque cylinder head bolts to factory specifications to prevent head gasket failure and coolant leakage into the combustion chamber.
Seasonal & Environment Servicing
In dusty environments, inspect the air filter restriction indicator daily and replace the primary element at 500 hours instead of the standard 1,000-hour interval. Clean radiator and charge air cooler fins daily to prevent overheating in high-ambient temperatures up to 43°C (110°F). In cold climates, verify coolant freeze protection levels before winter operation. Inspect battery chargers and heater pads to ensure reliable starting in low-temperature conditions. Adjust fuel pressure settings if operating at high altitudes to maintain proper air-fuel ratio.
G3412 fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CID 0110 FMI 03 | Engine Coolant Temperature Sensor — Voltage Above Normal | Open circuit in the sensor wiring harness or a failed sensor element causing a short to the power supply. | Inspect the sensor wiring for damage or disconnection; replace the coolant temperature sensor if the circuit is intact. |
| CID 0190 FMI 08 | Engine Speed Sensor — Abnormal Frequency | Incorrect air gap between the speed sensor and the tone ring, a damaged sensor, or a damaged tone ring. | Check and adjust the sensor air gap; test the sensor output and inspect the tone ring for physical damage. |
| CID 0041 FMI 03 | 8-Volt DC Supply — Voltage Above Normal | Short to power on the 8-volt reference circuit shared by multiple sensors. | Disconnect sensors sharing the 8-volt supply one at a time to isolate the shorted component or wiring. |
| CID 0041 FMI 04 | 8-Volt DC Supply — Voltage Below Normal | Short to ground on the 8-volt reference circuit. | Disconnect sensors sharing the 8-volt supply one at a time to locate the component causing the ground fault. |
| CID 0262 FMI 03 | 5-Volt Supply — Voltage Above Normal | Short to power on the 5-volt reference circuit used by electronic sensors. | Isolate the fault by disconnecting sensors on the 5-volt circuit individually until the code clears. |
| CID 0262 FMI 04 | 5-Volt Supply — Voltage Below Normal | Short to ground on the 5-volt reference circuit. | Disconnect sensors on the 5-volt circuit individually to identify the shorted component or wiring. |
| CID 0248 FMI 09 | CAT Data Link — Abnormal Update Rate | Communication fault on the data link, often caused by damaged wiring, poor connections, or termination issues. | Inspect the data link wiring for damage and verify termination resistance; check connector pins for corrosion. |
| CID 0168 FMI 04 | System Voltage — Voltage Below Normal | Low battery voltage, failing alternator, or poor electrical connections. | Check battery charge state, alternator output, and clean/tighten all ground and power connections. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
G3412 attachments & work tools
Generator Enclosures
Factory-designed bolt-on enclosures provide noise reduction and weather protection for stationary installations. Flexible packaging options allow for cost-effective integration into facility infrastructure.
Fuel Systems
Bolt-on system expansion attachments support natural gas, biogas, field gas, and propane fuel sources. Configurations are designed for maximum performance on low-pressure pipeline natural gas supply.
Control & Monitoring
EMCP 4.2 or EMCP 4.3/4.4 control panels provide engine governing, ignition, and air/fuel ratio management. Scalable systems support load sharing modules and remote monitoring software for paralleling arrays.
Electrical Output
SR4B generator ends are matched to the engine's performance characteristics for high efficiency. Voltage options include 208V, 220V, 440V, 277/480V, and 346/600V for 60 Hz applications.
Cooling & Exhaust
Liquid cooling systems are rated for standard ambient temperatures up to 43°C (110°F). Exhaust systems are included in standard open configurations to manage emissions and heat rejection.
All G3412 assemblies by section
Every catalogued assembly group for the Caterpillar G3412. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Air Inlet And Exhaust System
138-7537 Air Cleaner Gp
| 13***37 | Air Cleaner Group | 1 |
4w-6339 Air Cleaner Gp
| 4W***39 | Air Cleaner Group | 1 |
4w-5828 Cap As-Air Cleaner
| 4W***28 | Cap As-Air Cleaner | 1 |
113-5850 Cover Gp-Exhaust
| 11***50 | Cover Group-Exhaust | 1 |
8l-9859 Elbow-Exhaust
| 8L***59 | Elbow-Exhaust | 1 |
2w-7847 Fitting Gp-Exhaust -Flexible
| 2W***47 | Fitting Group-Exhaust; -Flexible | 1 |
2w-7848 Fitting Gp-Exhaust
| 2W***48 | Fitting Group-Exhaust | 1 |
2w-7852 Flange Gp-Exhaust
| 2W***52 | Flange Group-Exhaust; Flange Group-Exhaust | 1 |
2w-7851 Flange Gp-Exhaust
| 2W***51 | Flange Group-Exhaust | 1 |
119-6230 Manifold Gp-Exhaust -Water Cooled
| 11***30 | Manifold Group-Exhaust; -Water Cooled | 1 |
308-1919 Manifold Gp-Exhaust -Water Cooled
| 30***19 | Manifold Group-Exhaust; -Water Cooled | 1 |
4w-6325 Mounting Gp-Air Cleaner
| 4W***25 | Mounting Group-Air Cleaner | 1 |
2w-4072 Muffler
| 2W***72 | Muffler | 1 |
2w-0950 Pipe Gp-Exhaust
| 2W***50 | Pipe Group-Exhaust | 1 |
Basic Engine
4p-7330 Camshaft Gp
| 4P***30 | Camshaft Group | 1 |
3n-8594 Cover Gp-Engine Lifting Eye
| 3N***94 | Cover Group | 1 |
162-2916 Cover Gp-Cylinder Block
| 16***16 | Cover Group-Cylinder Block | 1 |
4w-6732 Cover Gp-Flywheel Housing
| 4W***32 | Cover Group-Flywheel Housing | 1 |
107-7528 Cover Gp-Front Housing
| 10***28 | Cover Group-Front Housing; Cover Gp-Front Structure | 1 |
2w-3938 Cover Gp-Valve Mechanism
| 2W***38 | Cover Group-Valve Mechanism | 1 |
213-3202 Crankshaft As
| 21***02 | Crankshaft As | 1 |
251-2301 Crankshaft Gp
| 25***01 | Crankshaft Group | 1 |
126-1375 Cylinder Block As
| 12***75 | Cylinder Block As | 1 |
126-1372 Cylinder Block As
| 12***72 | Cylinder Block As | 1 |
126-1373 Cylinder Block Gp
| 12***73 | Cylinder Block Group | 1 |
101-3720 Cylinder Block Gp
| 10***20 | Cylinder Block Group | 1 |
288-0475 Cylinder Head As
| 28***75 | Cylinder Head As | 1 |
216-8340 Cylinder Head Gp
| 21***40 | Cylinder Head Group | 1 |
311-7557 Cylinder Head Gp
| 31***57 | Cylinder Head Group | 1 |
139-9028 Damper & Pulley Gp
| 13***28 | Damper & Pulley Group | 1 |
7n-8847 Drive Gp-Fan -Blower
| 7N***47 | Drive Group-Fan; -Blower | 1 |
149-7876 Fastener Gp-Generator Coupling
| 14***76 | Fastener Group-Generator Coupling | 1 |
1n-3473 Flywheel Gp
| 1N***73 | Flywheel Group | 1 |
4n-6341 Gear Gp-Front -Timing
| 4N***41 | Gear Group-Front; Front Timing Gear Group | 1 |
4n-3825 Gear Gp-Rear
| 4N***25 | Gear Group-Rear; Rear Timing Gear Group | 1 |
210-9076 Guard Gp-Belt
| 21***76 | Guard Group-Belt | 1 |
4w-6115 Housing Gp-Flywheel
| 4W***15 | Housing Group-Flywheel | 1 |
4n-5226 Housing Gp-Front
| 4N***26 | Housing Group-Front; Front Housing Group | 1 |
184-1667 Housing Gp-Front
| 18***67 | Housing Group-Front | 1 |
184-1666 Housing Gp-Rear
| 18***66 | Housing Group-Rear | 1 |
7n-1748 Lifting Gp-Engine
| 7N***48 | Lifting Group; Lifting Gp-Engine | 1 |
1w-1340 Mounting Gp-Alternator
| 1W***40 | Mounting Group-Alternator | 1 |
151-7794 Mounting Gp-Engine Flexible
| 15***94 | Mounting Group-Engine Flexible | 1 |
135-7659 Pan Gp-Oil -Engine
| 13***59 | Pan Group-Oil; -Engine | 1 |
257-2694 Piston & Rod Gp
| 25***94 | Piston & Rod Group | 1 |
135-8583 Pulley Gp-Crankshaft
| 13***83 | Pulley Group-Crankshaft | 1 |
104-4213 Rocker Arm Gp
| 10***13 | Rocker Arm Group | 1 |
104-4214 Rocker Arm Gp
| 10***14 | Rocker Arm Group | 1 |
319-0785 Seal Gp-Crankshaft -Rear
| 31***85 | Seal Group-Crankshaft; -Rear | 1 |
319-7401 Seal Gp-Crankshaft -Front
| 31***01 | Seal Group-Crankshaft; -Front | 1 |
149-2657 Support Gp-Engine
| 14***57 | Support Group-Engine | 1 |
220-3745 Valve Mechanism Gp
| 22***45 | Valve Mechanism Group | 1 |
Cooling System
4n-2388 Cooler Gp-Engine Oil
| 4N***88 | Cooler Group-Engine Oil; Engine Oil Cooler Group | 1 |
6n-4371 Fan Gp-Blower
| 6N***71 | Fan Group-Blower | 1 |
7w-6192 Fan Gp-Blower
| 7W***92 | Fan Group-Blower | 1 |
168-3252 Lines Gp-Coolant Drain
| 16***52 | Lines Group-Coolant Drain | 1 |
6n-4762 Lines Gp-Water -Radiator
| 6N***62 | Lines Group-Water; -Radiator | 1 |
7w-1620 Lines Gp-Water
| 7W***20 | Lines Group-Water | 1 |
6n-4875 Lines Gp-Water -Radiator
| 6N***75 | Lines Group-Water; -Radiator | 1 |
6n-1857 Lines Gp-Water -Bypass
| 6N***57 | Lines Group-Water | 1 |
5n-8012 Mounting Gp-Radiator
| 5N***12 | Mounting Group-Radiator | 1 |
137-1339 Pump Gp-Water
| 13***39 | Pump Group-Water | 1 |
4n-5837 Pump Gp-Water
| 4N***37 | Pump Group-Water; Pump Group-Water | 1 |
7e-9055 Radiator Gp
| 7E***55 | Radiator Group | 1 |
334-3316 Radiator Gp
| 33***16 | Radiator Group | 1 |
7e-9798 Radiator Gp
| 7E***98 | Radiator Group | 1 |
Electrical And Starting System
2n-2342 Valve As-Solenoid
| 2N***42 | Valve As-Solenoid | 1 |
105-7185 Harness As-Panel -Circuit Breaker
| 10***85 | Wiring Group; -Circuit Breaker | 1 |
5n-5692 Alternator Gp-Charging
| 5N***92 | Alternator Group-Charging; Alternator Gp (See Page 25) | 1 |
199-6173 Bar Gp-Ground
| 19***73 | Bar Group-Ground | 1 |
9x-9730 Battery Gp -Dry
| 9X***30 | Battery Group; (12 Volt)(Dry)(Each Includes) | 1 |
7l-7871 Battery Gp
| 7L***71 | Battery Group; (24-Volt)(24-Volt) | 1 |
7l-7872 Battery Gp
| 7L***72 | Battery Group | 1 |
107-3058 Box Gp-Extension Terminal
| 10***58 | Box Group-Extension Terminal | 1 |
169-0247 Box Gp-Extension Terminal
| 16***47 | Box Group-Extension Terminal | 1 |
113-0841 Circuit Breaker Gp
| 11***41 | Circuit Breaker Group | 1 |
169-1839 Circuit Breaker Gp
| 16***39 | Circuit Breaker Group | 1 |
175-1332 Circuit Breaker Gp
| 17***32 | Circuit Breaker Group | 1 |
6t-3645 Circuit Breaker Gp
| 6T***45 | Circuit Breaker Group; -60-Ampere | 1 |
168-0343 Circuit Breaker Gp
| 16***43 | Circuit Breaker Group | 1 |
113-0839 Circuit Breaker Gp
| 11***39 | Circuit Breaker Group | 1 |
5n-0369 Circuit Breaker Gp
| 5N***69 | Circuit Breaker Group | 1 |
175-1330 Circuit Breaker Gp
| 17***30 | Circuit Breaker Group | 1 |
175-1331 Circuit Breaker Gp
| 17***31 | Circuit Breaker Group | 1 |
175-1329 Circuit Breaker Gp
| 17***29 | Circuit Breaker Group | 1 |
113-0840 Circuit Breaker Gp
| 11***40 | Circuit Breaker Group | 1 |
4p-4635 Connection Gp-Electrical
| 4P***35 | Connection Group-Electrical | 1 |
103-8974 Connection Gp-Electrical
| 10***74 | Connection Group-Electrical | 1 |
7c-4858 Connection Gp-Electrical
| 7C***58 | Connection Group-Electrical | 1 |
9y-6496 Module Gp-Interface
| 9Y***96 | Control Group-Emcp Electronic; (Customer) | 1 |
163-6108 Control Gp-Timing
| 16***08 | Control Group-Timing | 1 |
344-7582 Control Gp-Timing
| 34***82 | Control Group-Timing | 1 |
158-6171 Conversion Ar
| 15***71 | Conversion Ar | 1 |
7w-1091 Cover-Extension Box
| 7W***91 | Cover-Extension Box | 1 |
106-1771 Fastener Gp-Extension Box
| 10***71 | Fastener Group-Extension Box | 1 |
195-8033 Fastener Gp-Wiring Harness
| 19***33 | Fastener Group-Wiring Harness | 1 |
211-0074 Guard Gp-Alternator
| 21***74 | Guard Group-Alternator | 1 |
169-4449 Harness As-Box
| 16***49 | Harness As-Box; (70-Pin)(Extension Terminal Box) | 1 |
187-8444 Harness As-Panel -Current Scroll Fuel System
| 18***44 | Harness As-Panel; -Current Scroll Fuel System | 1 |
187-8445 Harness As-Panel -Current Scroll Fuel System
| 18***45 | Harness As-Panel; -Current Scroll Fuel System | 1 |
195-8022 Harness As-Wiring -Engine Shutoff
| 19***22 | Harness As-Wiring; -Engine Shutoff | 1 |
193-3247 Harness As-Wiring -Kilowatt Relay
| 19***47 | Harness As-Wiring; -Kilowatt Relay | 1 |
169-4450 Harness As-Wiring -Current Transformer
| 16***50 | Harness As-Wiring; -Current Transformer | 1 |
195-8025 Harness As-Wiring -Governor
| 19***25 | Harness As-Wiring; -Governor | 1 |
3n-5718 Holder-Lamp
| 3N***18 | Holder-Lamp | 1 |
344-5865 Ignition Gp-Gas Engine
| 34***65 | Ignition Group-Gas Engine | 1 |
216-4015 Ignition Gp-Gas Engine
| 21***15 | Ignition Group-Gas Engine | 1 |
344-5864 Ignition Gp-Gas Engine
| 34***64 | Ignition Group-Gas Engine | 1 |
169-0256 Mounting Gp-Bus Bar
| 16***56 | Mounting Group-Bus Bar | 1 |
169-1846 Mounting Gp-Circuit Breaker
| 16***46 | Mounting Group-Circuit Breaker | 1 |
169-1858 Mounting Gp-Circuit Breaker
| 16***58 | Mounting Group-Circuit Breaker | 1 |
7w-1021 Mounting Gp-Circuit Breaker
| 7W***21 | Mounting Group-Circuit Breaker | 1 |
102-9942 Mounting Gp-Contactor
| 10***42 | Mounting Group-Contactor | 1 |
4w-6806 Mounting Gp-Contactor
| 4W***06 | Mounting Group-Contactor | 1 |
208-5385 Mounting Gp-Electronic Control
| 20***85 | Mounting Group-Electronic Control | 1 |
7w-0907 Mounting Gp-Transformer
| 7W***07 | Mounting Group-Transformer | 1 |
4w-8217 Neutral Bus Bar As
| 4W***17 | Neutral Bus Bar As | 1 |
4w-8216 Neutral Bus Bar As
| 4W***16 | Neutral Bus Bar As | 1 |
158-6181 Relay Gp
| 15***81 | Relay Group; -Engine Failure | 1 |
171-6833 Relay Gp -Common Alarm
| 17***33 | Relay Group; -Common Alarm | 1 |
239-9957 Sensor Gp-Liquid Level
| 23***57 | Sensor Group-Liquid Level; -Coolant Loss | 1 |
208-0946 Sensor Gp-Liquid Level
| 20***46 | Sensor Group-Liquid Level | 1 |
127-2018 Sensor Gp-Pressure
| 12***18 | Sensor Group-Pressure | 1 |
216-8684 Sensor Gp-Pressure
| 21***84 | Sensor Group-Pressure; -Torque Converter Oil | 1 |
9x-5392 Sensor Gp-Speed
| 9X***92 | Sensor Group-Speed; -Timing | 1 |
127-2016 Sensor Gp-Temperature
| 12***16 | Sensor Group-Temperature | 1 |
102-0050 Sensor Gp-Temperature
| 10***50 | Sensor Group-Temperature; -Engine Coolant | 1 |
212-6251 Shutoff Gp-Electrical
| 21***51 | Shutoff Group-Electrical | 1 |
2s-7227 Starting Motor Gp-Electric
| 2S***27 | Starter Group-Electric; Electric Starter Group | 1 |
338-3454 Starting Motor Gp-Electric
| 33***54 | Starting Motor Group-Electric | 1 |
6v-0927 Starting Motor Gp-Electric
| 6V***27 | Starting Motor Group-Electric | 1 |
237-1962 Starting Motor Gp-Electric
| 23***62 | Starting Motor Group-Electric | 1 |
7w-0926 Strip As-Terminal
| 7W***26 | Strip As-Terminal | 1 |
157-2792 Strip As-Terminal
| 15***92 | Strip As-Terminal | 1 |
7w-0928 Strip As-Terminal
| 7W***28 | Strip As-Terminal | 1 |
234-2424 Strip Gp-Terminal
| 23***24 | Strip Group-Terminal | 1 |
237-2927 Strip Gp-Terminal
| 23***27 | Strip Group-Terminal | 1 |
234-2425 Strip Gp-Terminal
| 23***25 | Strip Group-Terminal | 1 |
198-8793 Support Gp-Battery
| 19***93 | Support Group-Battery | 1 |
113-0860 Switch As-Auxiliary
| 11***60 | Switch As-Auxiliary; -Circuit Breaker | 1 |
7n-0718 Switch Gp-Disconnect -Battery
| 7N***18 | Switch As-Disconnect; -Battery-Ground Level | 1 |
169-1864 Switch Gp-Auxiliary -Circuit Breaker Position Indicator
| 16***64 | Switch Group-Auxiliary; -Circuit Breaker Position Indicator | 1 |
169-1866 Switch Gp-Auxiliary -Circuit Breaker Position Indicator
| 16***66 | Switch Group-Auxiliary; -Circuit Breaker Position Indicator | 1 |
216-6070 Switch Gp-Disconnect -Battery
| 21***70 | Switch Group-Disconnect; -Battery | 1 |
175-2308 Switch Gp-Magnetic
| 17***08 | Switch Group-Magnetic; -24-Volt-Start Relay-Main Relay | 1 |
175-2309 Switch Gp-Magnetic
| 17***09 | Switch Group-Magnetic; -24-Volt-Start Relay | 1 |
118-3534 Switch Gp-Magnetic
| 11***34 | Switch Group-Magnetic; -Start Relay | 1 |
7w-6003 Transformer -Current
| 7W***03 | Transformer | 1 |
244-4461 Transformer As -Current
| 24***61 | Transformer As; -Current | 1 |
9y-3849 Transformer As -Current
| 9Y***49 | Transformer As; -Current | 1 |
9y-3886 Transformer Gp-Current
| 9Y***86 | Transformer Group-Current | 1 |
5n-5431 Transformer-Current
| 5N***31 | Transformer-Current | 1 |
342-1762 Valve Gp-Solenoid
| 34***62 | Valve Group-Solenoid | 1 |
101-8639 Wiring Gp-Alternator
| 10***39 | Wiring Group-Alternator | 1 |
194-0906 Wiring Gp-Engine
| 19***06 | Wiring Group-Engine | 1 |
195-8030 Wiring Gp-Engine
| 19***30 | Wiring Group-Engine | 1 |
204-2515 Wiring Gp-Generator
| 20***15 | Wiring Group-Generator | 1 |
206-5551 Wiring Gp-Generator
| 20***51 | Wiring Group-Generator | 1 |
Enclosures, Guards And Bases
207-8040 Base Gp-Engine & Generator
| 20***40 | Base Group-Engine & Generator | 1 |
169-0240 Cover Gp-Generator
| 16***40 | Cover Group-Generator | 1 |
168-3241 Enclosure Gp-Generator
| 16***41 | Enclosure Group-Generator | 1 |
238-2689 Mounting Gp-Bracket
| 23***89 | Mounting Group-Bracket | 1 |
Engine Arrangement
299-9360 Engine Ar
| 29***60 | Engine Ar | 1 |
294-7599 General Ar
| 29***99 | General Ar | 1 |
Fuel System
138-0777 Actuator As-Governor
| 13***77 | Actuator As-Governor | 1 |
7w-1174 Carburetor Gp
| 7W***74 | Carburetor Group | 1 |
4w-6322 Carburetor Gp
| 4W***22 | Carburetor Group | 1 |
131-5451 Control As-Governor -Speed Control
| 13***51 | Control As-Governor; -Speed Control | 1 |
131-5454 Control As-Governor -Load Share Module
| 13***54 | Control As-Governor; -Load Share Module | 1 |
209-3660 Control Gp-Governor
| 20***60 | Control Group-Governor | 1 |
163-6112 Drive Gp-Governor
| 16***12 | Drive Group-Governor | 1 |
184-1668 Drive Gp-Governor
| 18***68 | Drive Group-Governor | 1 |
7w-2363 Regulator As-Gas Pressure
| 7W***63 | Regulator As-Gas Pressure | 1 |
7e-2478 Regulator Gp-Gas Pressure
| 7E***78 | Regulator Group-Gas Pressure | 1 |
Generators
7c-1781 Connection Gp-Generator Leads
| 7C***81 | Connection Group-Generator Leads | 1 |
189-6395 Connection Gp-Generator Leads -Neutral
| 18***95 | Connection Group-Generator Leads; -Neutral | 1 |
5n-4513 Connection Gp-Generator Leads
| 5N***13 | Connection Group-Generator Leads; Generator Leads Connection Group | 1 |
5n-4125 Connection Gp-Generator Leads
| 5N***25 | Connection Group-Generator Leads | 1 |
202-7402 Connection Gp-Generator Leads -Neutral
| 20***02 | Connection Group-Generator Leads; -Neutral | 1 |
5n-4126 Connection Gp-Generator Leads
| 5N***26 | Connection Group-Generator Leads | 1 |
7c-1846 Connection Gp-Generator Leads
| 7C***46 | Connection Group-Generator Leads | 1 |
7w-0925 Connection Gp-Terminal Strip
| 7W***25 | Connection Group-Terminal Strip | 1 |
7w-0927 Connection Gp-Terminal Strip
| 7W***27 | Connection Group-Terminal Strip | 1 |
237-2922 Connection Gp-Terminal Strip
| 23***22 | Connection Group-Terminal Strip | 1 |
237-2923 Connection Gp-Terminal Strip
| 23***23 | Connection Group-Terminal Strip | 1 |
5n-1713 Coupling Gp-Generator Drive
| 5N***13 | Coupling Group-Generator Drive | 1 |
183-4729 Cover Gp-Access -Control Panel-Rear
| 18***29 | Cover Group-Access; -Control Panel-Rear | 1 |
155-9401 Fastener Gp-Voltage Regulator
| 15***01 | Fastener Group-Voltage Regulator | 1 |
173-7078 Generator Ar
| 17***78 | Generator Ar | 1 |
5n-5092 Generator Ar
| 5N***92 | Generator Ar | 1 |
173-7080 Generator Ar
| 17***80 | Generator Ar | 1 |
173-7086 Generator Ar
| 17***86 | Generator Ar | 1 |
173-7081 Generator Ar
| 17***81 | Generator Ar | 1 |
173-7083 Generator Ar
| 17***83 | Generator Ar | 1 |
173-7087 Generator Ar
| 17***87 | Generator Ar | 1 |
173-7085 Generator Ar
| 17***85 | Generator Ar | 1 |
173-7084 Generator Ar
| 17***84 | Generator Ar | 1 |
173-7082 Generator Ar
| 17***82 | Generator Ar | 1 |
5n-5075 Generator Ar
| 5N***75 | Generator As | 1 |
173-7093 Generator Gp
| 17***93 | Generator Group | 1 |
173-7088 Generator Gp
| 17***88 | Generator Group | 1 |
5n-0043 Generator Gp
| 5N***43 | Generator Group; Generator Group | 1 |
173-7096 Generator Gp
| 17***96 | Generator Group | 1 |
173-7089 Generator Gp
| 17***89 | Generator Group | 1 |
173-7090 Generator Gp
| 17***90 | Generator Group | 1 |
173-7094 Generator Gp
| 17***94 | Generator Group | 1 |
173-7095 Generator Gp
| 17***95 | Generator Group | 1 |
5n-0060 Generator Gp
| 5N***60 | Generator Group; Generator Group | 1 |
173-7091 Generator Gp
| 17***91 | Generator Group | 1 |
173-7092 Generator Gp
| 17***92 | Generator Group | 1 |
290-5564 Heat Sink As
| 29***64 | Heat Sink As | 1 |
290-5565 Heat Sink As
| 29***65 | Heat Sink As | 1 |
194-5188 Heater Gp-Space -Generator
| 19***88 | Heater Group-Space; -Generator | 1 |
5n-2975 Installation Ar-Generator
| 5N***75 | Installation Ar-Generator | 1 |
4w-8211 Insulator -Circuit Breaker Mount
| 4W***11 | Insulator; -Circuit Breaker Mount | 1 |
4w-8212 Insulator -Circuit Breaker Mount
| 4W***12 | Insulator; -Circuit Breaker Mount | 1 |
123-8591 Mounting Gp-Voltage Regulator
| 12***91 | Mounting Group-Voltage Regulator | 1 |
205-2307 Mounting Gp-Voltage Regulator
| 20***07 | Mounting Group-Voltage Regulator | 1 |
4w-5271 Regulator As-Voltage
| 4W***71 | Regulator As | 1 |
309-1019 Regulator As-Voltage -Digital
| 30***19 | Regulator As-Voltage; -Digital | 1 |
6i-2963 Regulator Gp-Voltage
| 6I***63 | Regulator Group-Voltage | 1 |
121-6200 Regulator Gp-Voltage
| 12***00 | Regulator Group-Voltage | 1 |
7w-8991 Regulator Gp-Voltage
| 7W***91 | Regulator Group-Voltage | 1 |
143-9517 Regulator Gp-Voltage
| 14***17 | Regulator Group-Voltage | 1 |
153-3187 Rotor As
| 15***87 | Rotor As | 1 |
191-2919 Rotor As
| 19***19 | Rotor As | 1 |
191-2920 Rotor As
| 19***20 | Rotor As | 1 |
5n-0598 Rotor As
| 5N***98 | Rotor As | 1 |
Lubrication System
264-1491 Base As-Oil Filter -Engine
| 26***91 | Base As-Oil Filter; -Engine | 1 |
2n-8220 Breather Gp -Crankcase
| 2N***20 | Breather Group; Breather Gp-Crankcase | 1 |
4n-2481 Fastener Gp-Oil Pump Mounting -Engine
| 4N***81 | Fastener Group-Oil Pump Mounting; Oil Pump Mounting Fastener Group | 1 |
264-1492 Filter Gp-Engine Oil
| 26***92 | Filter Group-Engine Oil; -Engine | 1 |
169-2120 Fumes Disposal Gp
| 16***20 | Fumes Disposal Group | 1 |
185-9469 Gauge Gp-Oil Level (Dipstick)
| 18***69 | Gauge Group-Oil Level (Dipstick) | 1 |
288-5847 Lines Gp-Engine Oil
| 28***47 | Lines Group-Engine Oil | 1 |
249-2700 Lines Gp-Engine Oil Drain
| 24***00 | Lines Group-Engine Oil Drain | 1 |
168-3245 Lines Gp-Engine Oil Drain
| 16***45 | Lines Group-Engine Oil Drain | 1 |
6n-1030 Pump Gp-Engine Oil
| 6N***30 | Pump Group-Engine Oil; Engine Oil Pump Group | 1 |
168-3301 Pump Gp-Sump
| 16***01 | Pump Group-Sump | 1 |
168-3300 Pump Gp-Sump
| 16***00 | Pump Group-Sump | 1 |
Operator Station
151-6260 Control Gp-Emcp Electronic
| 15***60 | Control Group-Emcp Electronic | 1 |
101-0225 Control Gp-Emcp Electronic
| 10***25 | Control Group-Emcp Electronic | 1 |
137-5525 Control Gp-Emcp Electronic
| 13***25 | Control Group-Emcp Electronic | 1 |
118-0175 Control Gp-Emcp Electronic
| 11***75 | Control Group-Emcp Electronic | 1 |
133-6350 Control Gp-Emcp Electronic
| 13***50 | Control Group-Emcp Electronic; -Generator Set Control | 1 |
164-8923 Control Gp-Emcp Electronic
| 16***23 | Control Group-Emcp Electronic | 1 |
118-2070 Control Gp-Emcp Electronic
| 11***70 | Control Group-Emcp Electronic; -Generator Set Control + | 1 |
137-5526 Control Gp-Emcp Electronic
| 13***26 | Control Group-Emcp Electronic | 1 |
148-5368 Module Gp-Relay Driver
| 14***68 | Control Group-Emcp Electronic | 1 |
103-6101 Control Gp-Engine Monitoring
| 10***01 | Control Group-Engine Monitoring | 1 |
170-8400 Cover Gp-Control Panel
| 17***00 | Cover Group-Control Panel | 1 |
8m-7892 Ammeter Gp
| 8M***92 | Gauge As-Ammeter; (Ammeter) | 1 |
7w-2937 Gauge Gp-Engine Oil Pressure
| 7W***37 | Gauge Group-Engine Oil Pressure | 1 |
332-8866 Kit-Electronic Conversion -Generator Set Control +
| 33***66 | Kit-Electronic Conversion; -Generator Set Control + | 1 |
3n-5588 Lamp
9y-0931 Module As -Boost
| 9Y***31 | Module As-Series Boost | 1 |
3n-7818 Module Gp-Auxiliary Relay
| 3N***18 | Module Group-Auxiliary Relay | 1 |
3n-5568 Module Gp-Cycle Cranking
| 3N***68 | Module Group-Cycle Cranking | 1 |
123-7450 Module Gp-Relay Driver
| 12***50 | Module Group-Relay Driver; Control Gp-Engine Monitoring | 1 |
9x-0203 Module Gp-Relay Driver
| 9X***03 | Module Group-Relay Driver | 1 |
104-4704 Mounting Gp-Control Panel -Emcp Ii
| 10***04 | Mounting Group-Control Panel; -Emcp Ii | 1 |
7w-0919 Mounting Gp-Control Panel
| 7W***19 | Mounting Group-Control Panel | 1 |
7e-7078 Mounting Gp-Instrument Panel
| 7E***78 | Mounting Group-Instrument Panel | 1 |
119-6031 Panel Gp-Control
| 11***31 | Panel Group-Control | 1 |
169-0250 Panel Gp-Control
| 16***50 | Panel Group-Control | 1 |
169-0249 Panel Gp-Control
| 16***49 | Panel Group-Control | 1 |
204-9824 Panel Gp-Electronic
| 20***24 | Panel Group-Electronic | 1 |
204-6818 Panel Gp-Electronic
| 20***18 | Panel Group-Electronic | 1 |
204-6802 Panel Gp-Electronic
| 20***02 | Panel Group-Electronic | 1 |
204-6807 Panel Gp-Instrument -Emcp Ii
| 20***07 | Panel Group-Instrument; -Emcp Ii | 1 |
204-6806 Panel Gp-Instrument
| 20***06 | Panel Group-Instrument | 1 |
204-6805 Panel Gp-Instrument
| 20***05 | Panel Group-Instrument | 1 |
205-0845 Panel Gp-Instrument
| 20***45 | Panel Group-Instrument | 1 |
204-6815 Panel Gp-Instrument
| 20***15 | Panel Group-Instrument | 1 |
4w-6328 Panel Gp-Instrument
| 4W***28 | Panel Group-Instrument | 1 |
5n-3666 Lamp Gp
| 5N***66 | Relay Lamp Assembly | 1 |
Service Equipment And Supplies
5n-6689 Plate & Film Gp
| 5N***89 | Accessory Plate & Decal Group | 1 |
352-9862 Certification Gp-Generator Set
| 35***62 | Certification Group-Generator Set | 1 |
4w-8145 Chart-Circuit Breaker
| 4W***45 | Chart-Circuit Breaker | 1 |
4w-8000 Chart-Control Panel
| 4W***00 | Chart-Control Panel | 1 |
7e-4300 Chart-Instrument Panel
| 7E***00 | Chart-Instrument Panel | 1 |
6l-4502 Chart-Plate & Film
| 6L***02 | Chart-Plate & Film | 1 |
205-7860 Film Gp -Product Identification
| 20***60 | Film Group; -Product Identification | 1 |
4p-3317 Kit-Installation -Exciter
| 4P***17 | Kit-Installation; -Exciter | 1 |
7c-0556 Kit-Space Heater
| 7C***56 | Kit-Space Heater | 1 |
7w-9833 Kit-Transformer Isolation
| 7W***33 | Kit-Transformer Isolation | 1 |
208-7866 Plate & Film Gp
| 20***66 | Plate & Film Group | 1 |
G3412 serial number reference
Locate the Product Identification Number (PIN) plate on the engine block or generator frame. The serial prefix is the first three characters of the last eight digits of the PIN (the final alphanumeric sequence).
| Prefix | Identifies | Notes |
|---|---|---|
| 9RR | G3412 GEN SET ENGINE | Gas engine variant. Source lists this prefix under 'G3412 GEN SET ENGINE'. |
| KAP | G3412 GENERATOR SET | Gas generator set variant. Source lists this prefix under 'G3412 GENERATOR SET'. |
| R7A | G3412 GENERATOR SET | Gas generator set variant. Source lists this prefix under 'G3412 GENERATOR SET'. |
| 6ZM | G3412 SI-TA Gas Generator Engine | Gas engine variant. Source identifies '6ZM' as the prefix for a G3412 SI-TA gas generator engine (Arrangement the OEM part reference, 419 kW). |
Frequently asked questions
What engine does the G3412 use?
The G3412 uses the G3412C, a 27-liter (1,648 in³) V12, four-stroke, turbocharged spark-ignited natural gas engine with an ADEM A4 electronic governor.
What is the operating weight of the G3412 generator set?
The dry weight varies by configuration: approximately 6,500 kg (14,330 lb) for the narrow base open skid, and up to 10,886 kg (24,000 lb) for sound-attenuated enclosures.
What replaced the G3412?
The G3412 was succeeded by the G3500 series engines, which offer higher power density and improved emissions compliance for modern standby and prime power applications.
What G3412 owners discuss
What are the known powertrain and structural behaviors of the Caterpillar G3412 engine?
The G3412 is built on the G3400 platform and is designed for continuous duty gas compression applications such as gas lift, gas gathering, and wellhead compression. It delivers a maximum rating of 600 BHP (447 bkW) at a rated speed of 1800 rpm. The engine features a V-12 configuration with a bore of 137 mm (5.40 inches) and a stroke of 152 mm (6.00 inches). Total displacement is 27.0 liters. It is turbocharged and aftercooled. The dry weight is 2,730 kg (6,018 lbs). Dimensions are 1,980 mm in length, 1,300 mm in width, and 1,285 mm in height. Emissions compliance for rich burn configurations is standard for export only. The flywheel and housing are SAE No. 0 with 151 teeth. Rotation from the flywheel end is counter-clockwise. Oil change intervals are specified at 250 hours. Lube system refill capacity is 139.0 liters. Cooling system refill capacity is 58.0 liters. Power output ranges from 476.0 bkW (647 bhp) minimum to 551.0 bkW (750 bhp) maximum depending on configuration. Varies by configuration/series for specific power ratings and emissions packages. The engine is cast with engine blocks, heads, cylinder liners, and flywheel housings manufactured in-house by Caterpillar. Over 60 years of natural gas engine production experience informs the design. The S•O•SSM program matches oil and coolant samples against Caterpillar set standards to determine internal engine component condition, presence of unwanted fluids, and combustion by-products. Site-specific oil change intervals are determined via this program. Preventive maintenance agreements are available for repair-before-failure options. More than 2,200 dealer outlets provide service. Cat factory-trained dealer technicians service every aspect of the petroleum engine. Cat parts and labor warranty is available. Have your dealer verify final emissions compliance and warranty terms for your specific region and application.
What are the common wear patterns or structural issues reported for the Caterpillar 3412 engine series?
Reported issues include severe overtightening of bolts indicating previous disassembly, fittings jammed in non-threaded holes where core plugs should be, and loose injector retainers. Heavy rust on assemblies and signs of previous rust on liners suggest storage in damp environments. The oil cooler may contain copper shards in the water side. The front main seal may leak. Bearing shells can suffer cavitation/erosion likely caused by water in the oil. Liners can be severely pitted on the outside due to cavitation from the crankcase design. Conrod small end bearings may show wear. Cylinder heads may have valve steps requiring replacement. Heavy build-up of carbon/oil/sludge behind plugs is common. Crankshaft scoring can occur. Conrod shank bolts may wear and allow movement. Burnt through HEUI pumps have been reported. Camshaft failure, connecting rod failure, cracked cylinder heads, crankshaft failure, dropped valves, extreme blow-by, lack of oil or oil pressure, lifter/roller failure, overfueling, scored pistons and liners, and spun crankshaft bearings are listed as common failures. Have your dealer verify the condition of liners and bearings during overhaul.
What electrical or sensor issues are associated with the G3412 or 3412 series?
Specific electrical or sensor issues for the G3412 are not detailed in the provided sources. The S•O•SSM program monitors oil and coolant conditions but does not specify sensor failure modes. Burnt through HEUI pumps are noted as a failure mode in related contexts. Have your dealer verify electrical system integrity and sensor calibration.
What should be checked when buying a used G3412 or 3412 engine?
Check for severe overtightening of bolts indicating previous disassembly. Inspect for fittings jammed in non-threaded holes. Verify injector retainers are secure. Look for heavy rust on assemblies and previous rust on liners. Inspect the oil cooler for copper shards in the water side. Check the front main seal for leaks. Examine bearing shells for cavitation/erosion. Inspect liners for severe pitting on the outside. Measure conrod small end bearings for wear. Inspect cylinder heads for valve steps. Check for heavy build-up of carbon/oil/sludge behind plugs. Look for crankshaft scoring. Measure conrod shank bolts for wear and movement. Verify the condition of the oil cooler and front main seal. Have your dealer verify the engine's internal condition and history.
What are the fluid specifications and capacities for the G3412?
Lube system refill capacity is 139.0 liters. Cooling system refill capacity is 58.0 liters. Oil change intervals are specified at 250 hours. Site-specific oil change intervals are determined via the S•O•SSM program. The S•O•SSM program matches oil and coolant samples against Caterpillar set standards. Use genuine Cat coolant to prevent recurrence of liner pitting. Have your dealer verify the correct fluid specifications for your specific application and region.
What are the key specifications for the G3412 gas compression engine?
Maximum rating is 600 BHP (447 bkW). Rated speed is 1800 rpm. Emissions for rich burn are standard for export only. Bore is 137 mm (5.40 inches). Stroke is 152 mm (6.00 inches). Displacement is 27.0 liters. Aspiration is turbocharged and aftercooled. Dry weight is 2,730 kg (6,018 lbs). Oil change interval is 250 hours. Rotation from flywheel end is counter-clockwise. Flywheel and housing are SAE No. 0. Flywheel teeth are 151. Lube system refill is 139.0 liters. Cooling system refill is 58.0 liters. Length is 1,980 mm. Width is 1,300 mm. Height is 1,285 mm. Power ranges from 476.0 bkW (647 bhp) to 551.0 bkW (750 bhp). Varies by configuration/series. Have your dealer verify the exact power rating and emissions package for your application.
What maintenance programs are available for the G3412?
The S•O•SSM program matches oil and coolant samples against Caterpillar set standards to determine internal engine component condition, presence of unwanted fluids, and combustion by-products. Site-specific oil change intervals are determined via this program. Preventive maintenance agreements are available for repair-before-failure options. More than 2,200 dealer outlets provide service. Cat factory-trained dealer technicians service every aspect of the petroleum engine. Cat parts and labor warranty is available. Have your dealer verify the availability of preventive maintenance agreements in your area.
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Serial-range & configuration variants
This page covers the Caterpillar G3412. Related factory variants of the same model family:
G3412
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