Caterpillarengine - industrialpumper

Caterpillar SCT673

Maintenance schedule, common problems & OEM parts breakdown

The Caterpillar SCT673 is not a mobile machine but a factory catalog arrangement for a truck-mounted industrial "Pumper" package built around Caterpillar's 3412C mechanical-diesel V-12 engine, a 27-liter block (137 mm bore x 152 mm stroke) drawn from the same industrial engine family as the 3408C and paired arrangements such as SPS342, SPT342, and SPT343. As a bare power package rather than a chassis-based product, it was built to drive oilfield well-service pumps mounted on a customer-supplied truck deck, with the engine, radiator, air cleaner, and drive coupling supplied as a matched skid or frame-mount unit rather than a standalone "machine" with its own model-year production run. Caterpillar identifies SCT673-built units under serial prefix 4TZ; no separate chassis, undercarriage, or operator station applies, since the pumper is the power end of a larger well-service rig assembled by the truck and pump-skid builder.

Because the SCT673 is a catalog arrangement rather than a numbered machine generation, there is no documented predecessor or successor model in the way a dozer or excavator series would have one; it sits alongside sibling pumper and generator-set arrangements that share the same 3412C engine block but differ in cooling package, gearing, or mounting footprint. What varies across SCT673-tagged units in the field is mainly the accessory package: radiator core size, air cleaner configuration, and coupling/PTO hardware were matched to the pump and truck builder's specification, which is why published cooling system fill varies by build rather than following one fixed number. In the used and parts market today, the SCT673 designation mainly shows up on engine, cooling, fuel system, and drivetrain-coupling parts lookups for oilfield service trucks running a 3412C, and buyers searching the model number are almost always sourcing a rebuild kit or replacement part for that engine rather than shopping for a complete machine.

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 SCT673 specifications

Engine

Product type	SCT673 is Caterpillar's parts-catalog code for a truck-mounted industrial pumper unit (a diesel engine driving a well-service pump), not a standalone mobile machine class.
Engine identity	Built around the Caterpillar 3412C, a 65-degree V-12 mechanical diesel of about 27 L displacement (137 mm bore x 152 mm stroke). Cat parts-catalog references identify the arrangement directly as a 3412C engine for a truck-mounted pumper, and fitment listings for the cylinder head, seals, oil pump, and sensors confirm the shared 3412/3412C block.
Gross/net power	Not published specifically for the SCT673 arrangement
Displacement / cylinders	Approximately 27 L, V-12, 137 mm bore x 152 mm stroke (3412C base engine)
Emissions tier	Not published; genuine parts listings for this code do not indicate a certified emissions tier

Weights

Operating weight	Not published — this is a bare engine/pump-drive package mounted on a customer-supplied truck deck, not a complete machine with a factory shipping weight
Shipping weight	Not published; varies with the radiator, coupling, and accessory package chosen by the truck/skid builder

Dimensions

Transport length/width/height	Not published
Other dimensions	Not published — no factory dimensional spec sheet exists for this arrangement

Performance

Pump/engine performance figures

Not published (rated speed, flow/head, or drawbar-type figures are not documented for this code)

Service capacities (summary)

Fuel tank	Not a fixed factory capacity — bare pump-drive engine; fuel tank is supplied and sized by the truck or skid builder
Hydraulic system	Not applicable — no integrated hydraulic system on this bare engine package
Engine oil	139 L (36.7 US gal), 3412C base-engine lube system — see the fluid chart for the recommended grade
Cooling system	58-67 L (15.5-17.7 US gal), varies by radiator/heat-exchanger package

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

SCT673 fluids & capacities

System	Capacity	Recommended fluid
Engine crankcase (with filter) - lube oil system	139 L (36.7-36.8 US gal)	Cat DEO or Cat DEO-ULS Diesel Engine Oil. SAE 15W-40 covers most ambient ranges; switch to SAE 10W-30 for consistently cold starting conditions below roughly 0C (32F). Confirm exact grade against the oil-viscosity-by-ambient-temperature table in the engine OMM before fill.
Cooling system	58-67 L (15.5-17.7 US gal), varies by radiator/heat-exchanger package	Cat ELC (Extended Life Coolant), premixed 50/50, no supplemental coolant additive needed; or Cat DEAC (conventional heavy-duty antifreeze/coolant) with SCA maintained per the OMM's coolant-conditioner schedule. Do not mix ELC and DEAC in the same system.
Fuel system / fuel tank	Not a fixed engine-package capacity - this is a bare industrial/pump-drive engine; fuel tank is skid- or site-supplied and sized to the application	Diesel fuel per Cat fuel specification (No. 2-D diesel, low- or ultra-low-sulfur per emissions requirements for the install region).
Grease points (accessory/fan drive, if equipped)	Not separately quantified in the engine OMM - lubricate per standard interval, not a bulk-fill system	Cat multipurpose grease (Cat MPGM) or equivalent NLGI No. 2 lithium-complex grease at points specified in the lubrication chart, where fitted.

Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.

Caterpillar SCT673 maintenance schedule

Service interval	Tasks
Every 10 h	Check crankcase oil level with engine stopped and correct before restart Inspect cooling system level at the sight glass or overflow bottle and top off with the specified coolant blend Drain water and sediment from primary fuel filter/water separator Walk down the pump drivetrain and skid mounting for fresh leaks, loose fasteners, or coolant/fuel seepage Listen for abnormal turbocharger or gear-train noise during warm-up before pump engagement
Every 50 h	Check and record battery electrolyte level and terminal condition Inspect drive belts for glazing, cracking, and correct tension Grease external pump-drive linkage and clutch/PTO coupling points per the lube chart Check radiator/heat exchanger fins and screens for debris that can restrict cooling airflow
Every 250 h	Change engine oil and replace the full-flow and bypass oil filter elements Replace the secondary fuel filter element and re-prime the fuel system Check and adjust alternator and fan belt tension Sample coolant and verify supplemental coolant additive (SCA) concentration, topping up as needed Clean or replace the engine air cleaner element based on service indicator reading Inspect the crankcase breather and clean if restricted
Every 500 h	Take an engine oil sample for lab analysis ahead of the scheduled change Inspect valve lash and adjust if outside factory tolerance Check turbocharger mounting, boost lines, and wastegate linkage for play or leakage Inspect the fuel transfer pump and injection pump drive for correct operation Check engine mounts, pump-drive coupling, and skid isolators for wear or cracking
Every 1,000 h	Change coolant filter/conditioner element and re-verify SCA level Inspect and re-torque cylinder head bolts and manifold fasteners per spec if indicated by trend data Check fuel injection timing and rack setting against the factory calibration card Inspect water pump for shaft play and seal weepage Clean cooling system fins/tube bundle of oilfield dust and debris buildup
Every 2,000 h	Perform a full valve lash inspection and adjustment across all cylinders Inspect turbocharger cartridge for shaft end play and bearing wear, rebuild or exchange as needed Test and recalibrate fuel injection pump timing and rack travel Inspect and pressure-test the cooling system, replacing hoses and clamps showing age-hardening Check and reset governor linkage and high-idle/low-idle settings
Every 6,000 h	Send coolant for full lab analysis and perform a complete coolant system flush and refill Inspect and recondition or replace fuel injection nozzles/injectors as a set Inspect cylinder liner protrusion and ring condition through a top-end borescope check if oil consumption or blow-by trends warrant it Rebuild or exchange the turbocharger center section
Every 12,000 h	Plan a top-end overhaul: cylinder heads, liners, pistons, and rings inspected or replaced as a set Recondition or replace main and rod bearings based on crankshaft journal wear readings Overhaul the water pump and replace all cooling system hoses, belts, and gaskets as a set Rebuild the fuel injection pump housing and governor assembly

Servicing the SCT673 beyond the schedule

Predictive Maintenance & Fluid Analysis

Run scheduled oil sampling on the 3412C's 27-liter crankcase to track soot loading and bearing wear trends typical of continuous-duty pump-drive service. Pair it with coolant SCA testing to catch liner cavitation risk early in a V-12 wet-liner block, and track fuel filter differential pressure to flag injection pump wear before it shows up as rough running or lost rack travel under load.

Corrective & Common Repairs

Most SCT673 field repairs trace to the fuel system and cooling circuit: injection pump and nozzle wear from continuous high-load pumping duty, water pump seal weepage, and radiator/heat exchanger fouling from oilfield dust. Turbocharger bearing wear and drive-coupling misalignment between the engine and the pump end are the next most common corrective jobs on these truck-mounted packages.

Overhaul & Rebuild Points

Top-end work on the 3412C centers on cylinder liner, piston, and ring condition after extended continuous-duty running, with main and rod bearing inspection driven by oil analysis trends rather than a fixed calendar. Because the SCT673 has no published overhaul-hour spec of its own, plan major work around oil consumption, blow-by, and coolant contamination signals rather than a generic mileage figure.

Seasonal & Environment Servicing

Oilfield pumper duty means dust-heavy intake air and wide ambient swings, so air cleaner service intervals should tighten in dry, dusty locations regardless of the hour clock. Verify coolant freeze protection before cold-weather deployment and check block heater and battery condition, since these truck-mounted units are often staged outdoors between well jobs with no shelter.

SCT673 common service parts

Part number	Part	Notes
1R-0749	Filter-Fuel	Fuel system service	Check fitment →
8H-2778	Seal-Ring	Fuel system service	Check fitment →
8H-7202	Case As-Fuel Filter	Fuel system service	Check fitment →
9M-2342	Filter Element As-Fuel	Fuel system service	Check fitment →
5P-2645	Elbow-Unfiltered Fuel From Adapter	Fuel system service	Check fitment →

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SCT673 fault codes & troubleshooting

Code	Meaning	Likely cause	What to do
LOW OIL PRESSURE (shutdown/alarm lamp)	Engine oil pressure dropped below the protective threshold and the hydramechanical safety circuit trips the fuel shutoff or lights the alarm.	Low oil level, worn or failed oil pump, plugged filter, or a faulty oil pressure sending switch.	Stop the unit, check oil level and filter condition, verify the pressure switch/sender before restart.
HIGH COOLANT TEMPERATURE (shutdown/alarm lamp)	Coolant temperature exceeded the protective limit, triggering the alarm or fuel shutoff.	Low coolant, blocked radiator or heat exchanger, failed water pump, or a stuck thermostat.	Stop pumping operation, check coolant level and flow, inspect water pump and cooling circuit before restart.
OVERSPEED SHUTDOWN	Engine speed exceeded the governor's protective limit (roughly 10-20 percent above rated), tripping the mechanical overspeed device and cutting fuel.	Governor linkage malfunction, sudden loss of pump load, or a sticking fuel rack.	Investigate governor linkage and fuel rack before the required manual reset; do not restart until the cause is found.
LOW COOLANT LEVEL (alarm/shutdown, if equipped)	Coolant level sensor reports level below the safe minimum.	External coolant leak, hose or gasket failure, or a faulty level sensor/float.	Check for external leaks, top off coolant, inspect the level sensor wiring and float before restart.
FAILURE TO START / OVERCRANK	Engine did not start within the allotted number of cranking cycles.	Interrupted fuel supply, air in the fuel system, weak batteries, or a starter fault.	Check fuel supply and bleed air from the system, verify battery and starter condition, then retry per the start procedure.
EMERGENCY STOP	Manual emergency-stop control was activated, cutting fuel and/or combustion air to the engine.	Operator-initiated safety stop, or a wiring fault holding the E-stop circuit closed.	Confirm position of the E-stop button or lanyard, inspect wiring and reset per procedure before restart.
AIR SHUTOFF ACTIVATED	The intake air shutoff valve closed, stalling the engine by cutting combustion air rather than fuel.	Manual trip during an overspeed/runaway event, or accidental trip of the safety shutoff linkage; common as an added oilfield safety feature on well-service pump engines exposed to combustible vapors.	Determine why the shutoff tripped (runaway vs. accidental), reset the valve linkage, and inspect for vapor ingestion before restart.

Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.

SCT673 attachments & work tools

Application / carrier equivalent

SCT673 is a factory arrangement of the Cat 3412C V-12 diesel built for a truck-mounted pumper unit, not a standalone genset or a machine with ground-engaging work tools. This arrangement supplies power to oilfield well-service pump trucks (cementing, fracturing, and acidizing type units) rather than driving buckets, blades, or other attachments.

Base engine

Underlying engine is the Cat 3412C, a 65-degree V-12, four-stroke diesel of about 27 L displacement, sharing cylinder heads, seals, and core parts with the general 3412/3412C engine family. Parts commonality with 3412 and 3412C confirms the block, not a unique bespoke casting.

Flywheel and coupling arrangement

The arrangement includes a dedicated flywheel adapter group used to mate the engine output to the pump-truck drivetrain (gearbox/pump transmission) rather than a work-tool coupler. Large-frame 3412-family industrial engines typically run an SAE No. 0 or SAE No. 1 flywheel housing depending on the driven equipment; exact housing size for this specific pumper arrangement should be confirmed against the arrangement/serial number.

Guarding

A shield group covers the rotating flywheel/coupling area at the rear of the engine, consistent with guarding required where the engine output shaft connects to external pump gearing on a truck chassis. This is safety guarding for the drivetrain interface, not a work-tool guard.

Cooling arrangement

Truck-mounted pumper packages of this size class are commonly built with either an engine-driven radiator or a remote/chassis-mounted cooling package depending on how the pump unit is skidded or mounted on the truck frame. Which cooling arrangement ships with a given SCT673 unit varies by build and should be verified against the specific arrangement number.

Governor and controls

The 3412C in this power class is generally offered with a mechanical governor rather than full electronic (HEUI) control, matching the non-ADEM 3412C variant used in industrial pump-drive service. Operator controls and instrumentation on pumper installations are typically mounted at a truck-side control station rather than as an integrated engine control panel; specifics vary by pumping-unit builder.

Power takeoff / drive output

Engine output drives the truck's pump gearbox/transmission through the flywheel coupling rather than through a PTO gearbox offering multiple accessory drives. No ground-engaging attachments, buckets, or quick-coupler work tools apply to this engine.

All SCT673 assemblies by section

Every catalogued assembly group for the Caterpillar SCT673. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Air Inlet And Exhaust System

9y-8810 Aftercooler Gp-Water

0S***71	Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting	13
0S***90	Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As)	10
0S***17	Bolt --Use Open Hole In Compressor Body	1
0T***73	Bolt (3/8) (63.5mm Long) (On Cab Of Cover Assem.)	14

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4p-2785 Cartridge Gp-Turbocharger

1P***20	Ring-Seal	1
1S***70	Nut (.687" O.D.)	1
4P***85	Cartridge Group-Turbocharger	1
4P***17	Bearing-Thrust	1

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102-0292 Cartridge Gp-Turbocharger

10***92	Cartridge Group-Turbocharger	1
10***40	Ring-Seal	1
10***42	Kit-Cartridge; (Turbocharger)	1
10***81	Plate As-Backing	1

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9y-8811 Lines Gp-Air

0L***29	Bolt- 7.63 cm(3 In.) Long - Location "H"	2
0S***09	Bolt (3/4") Filler Tube Assembly To Transfer Drive Case	10
0S***71	Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting	8
0S***85	Bolt; 12.7 mm (1/2") Diameter X 38.1 mm (1 1/2") Length Generator To Engine	8

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4p-2919 Manifold Gp-Exhaust

10***06	Manifold-Exhaust; (End)	2
10***07	Manifold-Exhaust; (Middle)	2
10***12	Manifold-Exhaust	2
10***12	Spacer; (11.13x19.05x53-mm Thk)	20

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9y-9826 Shield Gp-Heat -Manifold

0T***02	Bolt; (3/8-16x0.625-In)(Shield To Head)	4
2W***74	Bracket	2
5M***94	Washer; Bracket To Tee, Bracket To Block, Tube As. To Tee, Tube As. To Oil Cooler	4
6B***82	Spacer; (0.406x0.75x0.312-In Thk)	4

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9y-8816 Shield Gp-Manifold -Rh

0T***02	Bolt; (3/8-16x0.625-In)(Shield To Head)	4
2W***74	Bracket	2
6B***82	Spacer; (0.406x0.75x0.312-In Thk)	2
9L***32	Washer; (10.2x25.5x2.5-mm Thk)(25.5 mm Od)	4

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9y-8813 Shield Gp-Manifold

0S***09	Bolt (3/4") Filler Tube Assembly To Transfer Drive Case	6
0S***85	Bolt; 12.7 mm (1/2") Diameter X 38.1 mm (1 1/2") Length Generator To Engine	2
2W***53	Bracket	1
2W***74	Bracket	2

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169-1918 Sleeve-Exhaust Manifold

16***18

Sleeve-Exhaust Manifold

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9y-8814 Turbocharger Gp

10***90	Turbocharger Group	2
2N***66	Locknut; (3/8-16-Thd)(High Temperature)	16
4P***82	Turbocharger Group	2
5M***94	Washer; Bracket To Tee, Bracket To Block, Tube As. To Tee, Tube As. To Oil Cooler	16

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102-0290 Turbocharger Gp

10***90	Turbocharger Group	1
10***92	Cartridge Group-Turbocharger	1
2W***42	Housing-Turbine; (Turbine)	1
6V***51	Bolt-High Temperature; (3/8-16x0.75-In)	8

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4p-2782 Turbocharger Gp

4P***82	Turbocharger Group	1
4P***85	Cartridge Group-Turbocharger	1
7E***82	Housing	1
7E***83	Housing; (Compressor)	1

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Basic Engine

9y-9466 Adapter Gp-Flywheel

3G***56	Washer-Special; (5.0mm Thk)	12
8M***55	Gear-Flywheel Starter; (136 Teeth)	1
9Y***45	Bolt-12 Point Head; (5/8-18x3.5-In)	12
9Y***45	Flywheel As	1

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4n-0965 Camshaft Gp

0S***09	Bolt (3/4") Filler Tube Assembly To Transfer Drive Case	2
10***74	Gear-Camshaft Drive; (86-Teeth)	1
1B***05	Key; (Woodruff)	1
2W***89	Camshaft As.	1

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7e-8818 Cover Gp-Cylinder Block

0S***66	Bolt-Pulley To Crankshaft Adapter	3
0S***94	Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly	2
0S***19	Bolt,Machine Gear Retaining Part Of Kit P/N 1w***46	2
2P***72	Cover Block R.H. Side	2

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2w-9319 Cover Gp-Cylinder Block

0L***51	Bolt Starting Engine Fuel Tank Bracket To Diesel Intake Manifold	2
0S***94	Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly	9
23***37	Seal-Integral	1
2P***72	Cover Block R.H. Side	1

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4n-6798 Cover Gp-Front Housing

0L***52	Capscrew (3/8 - 16 Nc X 3 1/4 Gd8, Hex)	6
0S***94	Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly	3
1A***29	Bolt (1-1/8") Tube Assembly To Transfer Drive Case	2
2P***74	Stud-Taperlock; (3/8-16x4.2-In)	3

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9y-9827 Cover Gp-Oil Pan -Lh

06***58	Seal-O-Ring; (Oil Pan Drain Plug)	1
0S***87	Bolt-Bracket Assembly To Timing Gear	2
0S***88	Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter	5
10***72	Seal-O-Ring; (40.64-mm Id)	1

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9y-8482 Cover Gp-Valve Mechanism -Lh Service

27***83	Seal-O-Ring	7
4W***80	Base-Valve Mechanism Cover	4
5P***78	Seal; (2.3-M) (Valve Mechanism Cover)	0
7C***14	Adapter	7

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4n-0922 Crankshaft Gp

11***66	Gear-Crankshaft; (99-Teeth)	1
19***23	Kit-Crankshaft Bearing; (Crankshaft)	0
2W***33	Seal Group-Crankshaft; (Front)	1
2W***34	Seal Group-Crankshaft; (Rear)	1

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126-1372 Cylinder Block As

12***72	Cylinder Block As	1
2W***15	Insert-Liner Seat; (1.605-mm Thk)(1.59mm Thk)	0
3P***23	Bolt-Bearing Cap; (7/8-14x7.75-In)	14
4N***85	Bearing-Sleeve; (1-In Wide)(Marked X)	5

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126-1375 Cylinder Block As

11***20	Seal-O-Ring; (Mid-Liner)	12
12***75	Cylinder Block As	1
14***17	Seal-O-Ring; (140.20mm Id)	12
14***72	Seal-Liner; (Coolant)	12

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126-1374 Cylinder Block Gp

11***27	Seal-O-Ring; (19.18mm Id)	8
12***72	Cylinder Block As	1
12***74	Cylinder Block Group	1
3B***45	Plug Flywheel Housing Turbocharger Drain Hole	1

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7e-3762 Cylinder Block Gp

12***75	Cylinder Block As	1
22***00	Plate-Spacer	2
22***01	Gasket-Plate	2
3B***45	Plug Flywheel Housing Turbocharger Drain Hole	1

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126-1373 Cylinder Block Gp

11***27	Seal-O-Ring; (19.18mm Id)	8
12***72	Cylinder Block As	1
12***73	Cylinder Block Group	1
3B***45	Plug Flywheel Housing Turbocharger Drain Hole	1

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143-0047 Cylinder Head As

14***46	Cylinder Head As	1
14***47	Cylinder Head As	1
17***88	Guide-Valve; (Standard)	24

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143-0046 Cylinder Head As

14***46	Cylinder Head As	1
1W***83	Insert-Valve Seat; (Exhaust)(Standard)	12
3B***23	Core Plug--Flywheel Housing Pinion Shaft Hole	12
3B***45	Plug Flywheel Housing Turbocharger Drain Hole	10

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9y-8510 Cylinder Head Gp

0L***52	Capscrew (3/8 - 16 Nc X 3 1/4 Gd8, Hex)	18
0T***55	Bolt; (3/8-16x4.25-In)(Location S)	2
10***20	Adapter-Nozzle; (Direct Injection)	12
10***92	Stud-Taperlock; (3/8-16x3.93in)	24

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141-3228 Cylinder Head Gp

12***21	Valve-Exhaust	12
12***22	Valve-Inlet	12
14***28	Cylinder Head Group	1
14***47	Cylinder Head As	1

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9y-8504 Damper & Pulley Gp

0L***29	Bolt- 7.63 cm(3 In.) Long - Location "H"	12
16***31	Damper As	2
6V***73	Bolt; (5/8-18x8.5-In)	12
8S***69	Washer; (0.656x1.125x0.5-In Thk)	12

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4n-6341 Gear Gp-Front -Timing

0S***71	Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting	1
0T***73	Bolt (3/8) (63.5mm Long) (On Cab Of Cover Assem.)	1
11***17	Plate-Thrust	1
11***12	Shaft-Drive Idler	1

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9y-8807 Housing Gp-Flywheel

0S***90	Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As)	1
0T***73	Bolt (3/8) (63.5mm Long) (On Cab Of Cover Assem.)	1
16***93	Gasket-Cylinder	1
1C***51	Bolt--Installation Of 2v***26 Retainer	4

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9y-8505 Housing Gp-Front

0L***43	Bolt 63.5 mm (3/8" X 2 1/2" -Cover Assembly To Fender	3
0L***52	Capscrew (3/8 - 16 Nc X 3 1/4 Gd8, Hex)	2
16***45	Gasket-Cylinder Block	1
17***11	Housing-Timing Gear	1

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9y-8806 Lifting Gp-Engine -Lh

0L***78	Bolt,Machine Governor And Decelerator Control	1
0S***85	Bolt; 12.7 mm (1/2") Diameter X 38.1 mm (1 1/2") Length Generator To Engine	4
2A***38	Bolt-(3/4" X 2-1/4")-Rops Mounting Bracket To Fender	2
2M***49	Washer-Retainer To Fan Bracket Assembly	4

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9y-8809 Pan Gp-Oil -Engine

2P***03	Bolt-Washer Head; (3/8-16x1.25-In)	40
3B***51	Plug (Use Without Low Temperature Sensor)	2
4N***51	Gasket; (Engine Oil Pan)	1
9Y***09	Pan Group-Oil; -Lh Service	1

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7e-3973 Piston & Rod Gp

12***12	Crown As-Piston	1
13***61	Ring-Piston; (Top)(Top)	1
15***56	Bolt-Special; (Oil Jet)	1
16***78	Rod As-Connecting	1

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7w-5927 Rocker Arm Gp

00***03	Ring-Retaining	2
0L***22	Plug (.656" Dia.)	2
10***03	Screw; (3/8-24x1.67-In)(Intake)	6
2D***42	Ball 6.35 mm(.25 In.)Diameter	1

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7w-5926 Rocker Arm Gp

00***03	Ring-Retaining	2
0L***22	Plug (.656" Dia.)	2
10***03	Screw; (3/8-24x1.67-In)(Intake)	6
2D***42	Ball 6.35 mm(.25 In.)Diameter	1

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7e-6385 Support Gp-Engine

0S***66	Bolt-Pulley To Crankshaft Adapter	4
4D***04	Washer,Flat Cover Mtg,Accessory Drive	4
4N***84	Support-Front Engine	1
7E***85	Support Group-Engine; -Front	1

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4n-4303 Trunnion Gp-Engine

0S***73	Bolt (102mm Long); (1/2-13x4-In)	6
4N***03	Trunnion Group-Engine; Engine Trunnion Group	1
4W***50	Adapter-Support	1
5P***45	Washer-Hard; (13.5x25.5x3-mm Thk)(Turbocharger Blanking Plate)	2

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4n-7352 Valve Mechanism Gp

10***89	Bridge-Valve	24
10***88	Valve Lifter Assem	24
23***85	Bolt-12 Point Head; (3/4-16x11.5-In)	1
30***43	Spring-Guide	24

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Cooling System

9y-8479 Coolant Conditioner Gp

1W***06	Hose Assem. 137 cm(53.94 In.)	1
1W***18	Filter-Coolant Conditioner; (Precharge)	1
2N***37	Elbow-Flared	1
3B***15	Bolt Guard Assembly To Accessory Drive Housing	4

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4n-2388 Cooler Gp-Engine Oil

10***77	Seal-O-Ring; (100.97mm Id)	2
4N***88	Cooler Group-Engine Oil; Engine Oil Cooler Group	1
7C***45	Core As-Oil Cooler; (Water Lines)	1

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4w-0419 Core Gp-Oil Cooler

4W***19	Core Group-Oil Cooler; -Transmission	1
5M***14	Pipe Plug Cylinder Block Oil Pressure	2

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9y-8480 Lines Gp-Water

1D***66	Bolt Bracket Assembly To Yoke	1
24***13	Regulator-Water Temperature; (92-Deg C)(Water, Coolant Temperature)	2
2H***93	Ferrule	1
2H***88	Bolt- 12 cm(4.75 In.) Long-Location "F"	3

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9y-8506 Lines Gp-Water

03***16	Elbow; (Pipe)	1
0S***71	Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting	4
0S***90	Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As)	3
0S***94	Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly	2

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4n-5837 Pump Gp-Water

10***49	Adapter-Inlet	1
11***79	Seal-O-Ring	1
11***80	Seal-O-Ring	1
13***39	Pump Group-Water	1

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137-1339 Pump Gp-Water

0S***91	Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82	1
10***30	Bearing As-Roller	1
11***21	Plug-Felt; (Water Pump Housing)	1
12***17	Seal Group; (Water Pump)	1

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Electrical And Starting System

9y-8500 Control Gp-Engine Electronic

11***89	Cover	1
11***19	Control Group-Engine Electronic	1
6V***79	Seal-O-Ring; (72.62-mm Id)	1
6V***89	Nut-Full (5/16 X 18 Thd)	3

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115-7719 Control Gp-Engine Electronic

11***19	Control Group-Engine Electronic	1
3E***99	Plate-Marking	1

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163-8516 Sensor Gp-Pressure

16***16	Sensor Group-Pressure; -Boost And Engine Oil	1
19***26	Harness As-Sensor; (16-18 Ga Wire)(Engine Oil Temperature)	1
19***27	Harness As-Sensor; (14-Ga Wire)(Engine Oil Temperature)	1
8T***31	Plug-Connector; (3-Pin)	1

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161-9926 Sensor Gp-Pressure

15***60	Kit-Connecting Plug; (3-Pin)(Engine Sensor Wiring Harness)	1
16***26	Sensor Group-Pressure; -Atmospheric Air, Turbo Inlet	1
18***40	Socket-Connector; (14-Ga To 18-Ga)(14-Ga To 18-Ga)	3
3E***68	Wedge-Plug Lock; (3-Pin)	1

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193-5518 Sensor Gp-Speed

18***35	Pin-Connector; (16-Ga To 18-Ga)	3
19***18	Sensor Group-Speed; -Engine	1
8T***32	Receptacle-Connector; (3-Pin)(Throttle Position Sensor)	1
9X***86	Sleeve; (Bulk) (15 cm)	0

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7x-1043 Sensor Gp-Temperature

18***35	Pin-Connector; (16-Ga To 18-Ga)	3
7X***43	Sensor Group-Temperature; (Scm Engine Oil Temp Sensor)	1
8T***32	Receptacle-Connector; (3-Pin)(Throttle Position Sensor)	1
9X***13	Sleeve (Order By cm)(Use As Required)	0

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120-4887 Wiring Gp-Engine

03***83	Screw-Machine	3
09***66	Washer; (Hard) (4.5x9x1mm Thk)	3
0L***52	Capscrew (3/8 - 16 Nc X 3 1/4 Gd8, Hex)	1
0S***71	Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting	2

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Engine Arrangement

151-4498 Engine Ar

11***75	Pump Group-Gov & Fuel Inj	1
12***87	Wiring Group-Engine	1
14***55	Pump Group-Fuel Priming	1
15***98	Engine Ar	1

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Fuel System

4n-7935 Cover Gp-Fuel Filter Base

1P***36	Gasket; (Fuel Priming Pump)(Fuel Priming Pump)	1
4N***35	Cover Group-Fuel Filter Base; Fuel Filter Base Cover Group	1
6N***14	Cover-Filter Base; (Fuel)	1
8C***17	Bolt; (1/4-20x1.375-In)	1

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7e-0524 Drive Gp-Governor & Fuel Pump

1T***14	Bolt-12 Point Head; (5/16-18x1-In)	1
6N***23	Slide	2
6N***56	Weight-Advance	2
7E***24	Drive Group-Governor & Fuel Pump	1

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4n-6925 Filter Gp-Fuel

1R***49	Filter-Fuel; (Advanced Efficiency)(Secondary)	2
3J***07	Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve	1
4N***25	Filter Group-Fuel; Filter Group-Fuel	1
6N***46	Base As-Fuel Filter	1

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9y-8483 Filter Gp-Primary Fuel

00***62	Elbow (To Primary Filter Base)	1
03***94	Connector-Flared	1
0S***91	Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82	2
1L***69	Ring-Retaining	1

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4p-8235 Governor Gp

10***23	Spacer; (7.5x11.3x17-mm Thk)	3
1N***00	Sleeve-Rack Control	1
1N***01	Spring-Link	1
1N***02	Seat-Spring	1

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4p-8482 Lever Gp-Governor Control

1H***00	Pin--To Compression Release Shaft	1
4P***89	Lever As	1
4P***52	Clamp	1
4P***82	Lever Group-Governor Control	1

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9y-8476 Lines Gp-Fuel Filter

03***47	Elbow-Filtered Fuel From Based Assembly	4
0S***88	Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter	7
0S***19	Bolt,Machine Gear Retaining Part Of Kit P/N 1w***46	1
2P***14	90 Degrees Str Thd Long Elbow (-6)	1

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4p-9631 Lines Gp-Fuel Injection

10***38	Screw-Machine	3
10***39	Screw As	3
10***88	Clamp As	1
11***09	Spacer; (Fuel Line)	1

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4p-9632 Lines Gp-Fuel Injection

10***38	Screw-Machine	5
10***39	Screw As	3
10***88	Clamp As	1
10***89	Clamp As	1

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4p-9484 Lines Gp-Fuel Injection

05***94	Bolt-12 Point Head; (3/8-16x1.75-In)	5
10***64	Tube As	1
13***04	Nozzle As-Fuel Injection	12
1S***04	Seal-O-Ring (18.42mm Id)	2

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108-6633 Pump Gp-Fuel Injection

10***02	Bonnet-Valve	1
10***04	Plunger & Barrel As	1
10***33	Pump Group-Fuel Injection	1
1N***57	Air Fuel Ratio Control Lines Group	1

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116-4074 Pump Gp-Fuel Injection

0S***15	Bolt 19 mm (.75 In.) Long Return Air Console To Enclosed Rops	26
10***33	Pump Group-Fuel Injection	12
11***94	Bushing	12
11***72	Camshaft As-Pump	1

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8n-3365 Pump Gp-Fuel Priming

10***08	Pump As; (Fuel Priming)	1
1B***82	Bolt (1.25 In. Long X .313 In. Dia.)	1
1J***71	Seal (10.52 Degrees I.D.); Seal-O-Ring -- To Adapter	2
1P***36	Gasket; (Fuel Priming Pump)(Fuel Priming Pump)	1

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4n-3287 Pump Gp-Fuel Priming

10***08	Pump As; (Fuel Priming)	1
1P***36	Gasket; (Fuel Priming Pump)(Fuel Priming Pump)	1
4N***87	Pump Group-Fuel Priming; Pump Group-Fuel Priming	1
7X***01	Bolt-Plt; (1/4unc X 1 1/4)	1

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145-8855 Pump Gp-Fuel Priming

13***41	Pump Group-Fuel Priming; (Hand)	1
14***55	Pump Group-Fuel Priming	1
1B***90	Bolt; (5/16-18x1.375-In)(Rh Front Cover)	1
1P***36	Gasket; (Fuel Priming Pump)(Fuel Priming Pump)	1

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116-4075 Pump Gp-Gov & Fuel Inj

0S***16	Screw,Cap,Hexagon H Receptacle Mtg; Bolt Brackets To Firewall Assembly	7
10***39	Solenoid-Rotary	1
10***73	Pump Group-Fuel Transfer	1
10***97	Servo Group-Rotary; -Fuel Inj Pump	1

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116-4073 Pump Gp-Gov & Fuel Inj

0S***16	Screw,Cap,Hexagon H Receptacle Mtg; Bolt Brackets To Firewall Assembly	2
10***82	Housing As-Drive	1
10***16	Plug; (3/8-32-Thd)(3/8-32 Unef 2a Thd)	1
10***10	Plug-Rack	1

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108-3797 Servo Gp-Rotary -Fuel Inj Pump

00***93	Seal-O-Ring (Id=52.07mm); (52.07-mm Id)	1
0S***16	Screw,Cap,Hexagon H Receptacle Mtg; Bolt Brackets To Firewall Assembly	1
10***95	Cover-Oil Pump	1
10***96	Cover-Servo Oil Pump Bypass	1

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Lubrication System

9y-2989 Breather Gp

2N***09	Clamp; (V-Band)	1
4F***90	Seal (2.10" Inside Diameter)	1
4N***68	Breather As; (Crankcase)	1
9Y***89	Breather Group	1

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4n-2481 Fastener Gp-Oil Pump Mounting -Engine

0L***43	Bolt 63.5 mm (3/8" X 2 1/2" -Cover Assembly To Fender	2
0S***90	Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As)	1
4N***81	Fastener Group-Oil Pump Mounting; Oil Pump Mounting Fastener Group	1
5M***94	Washer; Bracket To Tee, Bracket To Block, Tube As. To Tee, Tube As. To Oil Cooler	3

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2w-6537 Filler Gp-Engine Oil

12***97	Tube As	1
2N***09	Clamp; (V-Band)	1
2W***37	Filler Group-Oil	1
3F***56	"S" Hook	1

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9y-1911 Filter Gp-Engine Oil

0S***94	Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly	5
1P***67	Plunger; (Engine Oil Cooler Relief Valve)	1
1R***08	Filter As-Engine Oil; (Advanced Efficiency)(High Efficiency)	2
2P***60	Housing-Clutch	1

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9y-0992 Gauge Gp-Oil Level (Dipstick) -Lh Rear

0L***51	Bolt Starting Engine Fuel Tank Bracket To Diesel Intake Manifold	1
0S***91	Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***82	1
11***68	Seal-O-Ring; (15.54mm Id)	1
16***70	Plug	3

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9y-8484 Lines Gp-Engine Oil

0L***51	Bolt Starting Engine Fuel Tank Bracket To Diesel Intake Manifold	2
0L***70	Bolt (2-1/4") Filler Tube Assembly To Transfer Drive Case	5
0S***71	Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting	1
0S***90	Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As)	1

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9y-8812 Lines Gp-Turbocharger Oil

06***61	Seal-O-Ring (Id=40.87mm)	2
0L***51	Bolt Starting Engine Fuel Tank Bracket To Diesel Intake Manifold	5
0S***71	Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting	10
0S***85	Bolt; 12.7 mm (1/2") Diameter X 38.1 mm (1 1/2") Length Generator To Engine	2

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6n-1030 Pump Gp-Engine Oil

0S***71	Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting	4
1M***44	Bolt; (3/8-16x2-1/4 In)	2
1W***38	Shaft As-Pump Drive; (8-Teeth)	1
1W***39	Shaft As-Idler; (8-Teeth)	1

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Service Equipment And Supplies

6l-4502 Chart-Plate & Film

11***88	Film; (Identification) (Fuel Filter) (On Secondary Fuel Filter)	2
12***69	Plate-Information; (Engine)(Engine Rating, Glps)	0
3N***69	Tag-Instruction; (Engine Prestart)(English And Spanish)	1
3N***90	Plate Serial Number; On R.H. Rear Bank Of Cylinder Block As Viewed From Rear Of Engine	1

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SCT673 serial number reference

On Cat industrial engines the PIN/serial plate is mounted on the engine block or flywheel housing, often near the fuel injection pump or on the left side of the block below the cylinder head. Read the first 3 characters as the serial prefix (identifies the specific engine arrangement/build), followed by the sequential unit number; match the prefix against Cat's serial-prefix reference to confirm it belongs to the SCT673 arrangement rather than a shared-parts sibling.

Prefix	Identifies	Notes
4TZ	SCT673 Pumper — industrial engine	Serial prefix documented for the SCT673 Pumper in Cat industrial-engine prefix references. Base engine family, plant, and production years are not documented in available references — confirm with dealer.

Frequently asked questions

What engine powers the Caterpillar SCT673?

The SCT673 pumper arrangement is built around Caterpillar's 3412C, a mechanical-diesel V-12 of roughly 27 liters displacement (137 mm bore x 152 mm stroke), the same base engine used across the related SPS342, SPT342/343 pumper and generator-set arrangements.

What is the operating weight of the SCT673?

Caterpillar never published a standalone weight or dimensional spec sheet for the SCT673. It is a bare industrial engine/pumper power package meant to be mounted on a customer-built truck deck, so shipping weight depends on the radiator, coupling, and accessory package chosen rather than one fixed factory figure.

What replaced the Caterpillar SCT673?

No documented successor model exists. The SCT673 is a catalog arrangement number tied to the 3412C engine rather than a numbered machine series, so there is no factory-confirmed follow-on product; buyers researching a replacement should look at current Cat well-service engine packages built around later industrial engine platforms.

What SCT673 owners discuss

Is there much owner/mechanic discussion specifically about the SCT673 pumper code on forums?

Not really. SCT673 is a catalog designation for the pumper-truck package built around the 3412C V-12, and it rarely comes up by that code in shop-floor conversation. Techs and oilfield mechanics talk about "the 3412" or "the 3412C" on the truck, not the SCT673 arrangement number. The points below reflect general 3412C-family experience rather than SCT673-branded discussion, since dedicated commentary under that specific code is essentially absent.

What is the most talked-about fuel-system quirk on these mechanical 3412C engines?

A stuck injection pump rack. Owners describe the engine hanging at a fixed rpm (commonly cited around 1200) and refusing to idle down or shut off cleanly. The usual suspects are a gummed-up rack in its bore from varnish/contamination, or a failed governor drive to the flyweight assembly where the weights have worn through the thrust washer. Freeing a stuck rack in place is hit-or-miss even for experienced hands; a full governor rebuild or replacement is often the more reliable fix. Because this can leave an engine unable to shut down under its own controls, have your dealer or an experienced Cat mechanical-fuel-system tech verify and correct rack/governor condition before returning the unit to service.

What overheating causes come up most often with this engine family in truck-mounted service?

Restricted airflow through the radiator (dirty fins, weak fan clutch engagement) is the top complaint, especially in hot climates and under sustained pumping load. Next most common are worn water pump impellers, leaking or failed water regulator (thermostat) valves, and clogged or partially blocked oil coolers that let lube temperature climb alongside coolant temperature. Techs also flag leaking exhaust manifold gaskets and worn turbo jumper-tube connections as sources of excess under-hood heat that get mistaken for a cooling-system fault. Paint discoloration or bubbling on engine covers is treated as a tell-tale sign of a prior overheating event when looking at a used unit.

What electrical or sensor issues show up on the PEEC-controlled versions of this engine?

The engine speed/timing sensor is the recurring complaint: intermittent fault codes traced to oil intrusion into the sensor and rack-position connector plugs near the injection pump housing, and to worn stamped harness terminals that cause poor contact. Techs recommend checking that the sensor flange seats flush against the engine and cleaning/drying connectors before condemning the sensor itself. Rack-position sensor calibration also needs to be redone any time the governor housing is opened or its gasket is disturbed, since a mis-calibrated rack sensor will throw fueling and speed control off even with good wiring.

What wear pattern is typical for a 3412C-family engine running well-service pump duty?

Continuous high-load, low-variation running (driving a triplex or similar plunger pump through a PTO or direct drive) tends to accelerate PTO clutch wear and heat-cycle the water pump and oil cooler harder than typical over-the-road use. Owners running these on skid or truck-mounted pump packages report the clutch and drive coupling as consumable items tied to duty cycle rather than calendar time, and stress that fuel/oil analysis catches injector and rack wear earlier than waiting for a visible rpm or smoke complaint. Turbo bearing wear and manifold gasket leakage are also cited as more common on units that see sustained full-load pumping versus light-duty standby use.

Any known differences in behavior between the mechanical governor and the PEEC electronic add-on on this engine?

Community consensus is that the base fuel system is mechanically governed injection, with PEEC (the electronic control/monitoring layer) added on top for speed control, protection shutdowns, and panel integration rather than replacing the mechanical injection pump itself. This hybrid setup means fueling and injection timing troubleshooting still follows mechanical-pump procedures (rack position, timing, transfer pump pressure), while no-start, sensor-fault, or shutdown-relay complaints get chased through the PEEC/EMCP wiring and control module instead. Mixing up which system a given symptom belongs to is a common source of wasted diagnostic time reported by techs.

What should I check when looking at a used SCT673 pumper unit before buying?

Start the engine cold and listen for rough running or hunting rpm, then shut it down and restart after a short cool-down to see if it hesitates or hangs at a fixed speed, a sign of a sticking rack or governor problem. Check under the valve covers and oil fill for milky residue or fuel-diluted oil, inspect the radiator, oil cooler, and turbo jumper tubes for leaks and grime buildup, and look at engine covers for paint discoloration suggesting a past overheating event. On the drivetrain side, check PTO clutch engagement and the condition of the pump drive coupling, since these wear in proportion to pumping hours rather than truck mileage. Pull any available fault-code history from the control panel and ask for recent fuel/oil sample results if the seller has them. Because a stuck governor rack, worn PTO clutch, or turbo bearing wear are safety- and cost-significant findings, have your dealer or a qualified diesel technician verify engine and pump-drive condition with a proper inspection before finalizing purchase.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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