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Caterpillar 3408C Engine

The Caterpillar 3408C is a heavy-duty, 90-degree V8 industrial diesel engine representing an updated, refined generation of the core 3408 platform. It is highly regarded in marine propulsion, electrical power generation, and heavy industrial machinery for its mechanical simplicity, exceptional torque-rise capabilities, and long-term operating durability under high load factors. Key advancements in the "C" series include a rigid, single-piece cast-iron cylinder head to minimize combustion gas leakage, high-strength forged steel crankshafts capable of multiple regrinds, and premium alloy valves designed to extend overall time-between-overhauls (TBO). Cylinder Bore: 137 mm (5.4 inches). Piston Stroke: 152 mm (6.0 inches). Total Displacement: 18 liters (1099 cubic inches).

Fuel System Injection Type: Direct injection (DI) system delivering fuel straight into the combustion chamber. Delivery: A mechanical fuel transfer pump draws fuel through primary and secondary filters. Metering: High-pressure individual fuel injection pumps and lines deliver fuel to mechanical multi-hole nozzles. Regulation: Engine speed and fueling limits are governed via a hydra-mechanical or mechanical governor linked directly to the fuel rack.

Lubrication System Type: Full-pressure lubrication system utilizing a gear-driven oil pump. Filtration: Bypass and full-flow filtration with spin-on or cartridge filter elements. Cooling: Integrated water-cooled oil cooler maintains oil stabilization under continuous high-load operations. Cooling System Type: Forced-circulation liquid cooling loop. Circulation: High-capacity, gear-driven centrifugal jacket water pump. Temperature Control: Dual-element thermostats regulate temperature with an operating range usually between 82C and 99C (180°F-210F).

General Technical Data

Engine Specifications

Engine Model ............... Caterpillar 3408C
Engine Type ............... 4-cycle 8-cylinder V-block direct injection liquid-cooled diesel
Number of Cylinders ...............
Cylinder Arrangement ............... V-type
Engine Bore, in (mm) ............... 5.39 (137.0)
Engine Stroke, in (mm) ............... 5.98 (152.0)
Displacement, cu.in (L) ............... 1099 (18.0)
Rated Engine Power (Generator), hp (kW) ............... 300-600 (220-450)
Rated Engine Power (Marine), hp (kW) ............... 600-900 (220-665)
Rated Engine Speed, rpm ............... 1800-2100
Aspiration Type ............... Turbocharged or Turbocharged and Aftercooled
Operating Speed ............... 2000 rpm
Compression Ratio ............... 17:1-16:1
Firing Order ............... 1-8-7-5-4-3-6-2
Crankshaft Type ............... Forged steel
Piston Type ............... Cast-aluminum alloy
Con Rod Type ............... Forged steel
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure
Oil Pump Type ............... Gear-driven
Oil Filter Type ............... Full-flow, spin-on
Cooling System ............... Liquid-cooled
Water Pump Type ............... Gear-driven, centrifugal
Air Cleaner Type ............... Dry dual-stage
Starting System ............... Electric Starter
Electrical System ............... 12V or 24V
Alternator Rating, Amps ............... 130-200

Fuel System

Fuel System ............... Direct injection
Injection Pump Type ............... Plunger-type
Fuel System Control ............... Mechanical
Governor Type ............... Mechanical
Fuel Injector Type ............... Multi-hole
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 63-67 (1600-1700)
Overall Width, in (mm) ............... 47.2-51.2 (1200-1300)
Overall Height, in (mm) ............... 53.1-57.1 (1350-1450)
Dry Weight, lbs (kg) ............... 3300-3960 (1500-1800)

Maintenance Data

Service Information

Thermostat begins opening ............... 82C (180F)
Thermostat fully open ............... 99C (210F)
Cooling system pressure ............... 70-100 kPa (10-15 psi)
Operating oil pressure ............... 275-410 kPa (40-60 psi)
Idle oil pressure ............... 140-275 kPa (15-30 psi)
Intake Valve Clearance, in (mm) ............... 0.015-0.017 (0.38-0.43)
Exhaust Valve Clearance, in (mm) ............... 0.025-0.030 (0.64-0.76)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CD, CE, or CF-4
Engine Oil Capacity, qts (L) .................. 42.0-48.3 (40.0-46.0)
Coolant Capacity, qts (L) ............... 52.5-63.0 (50.0-60.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 500 hours
Inspect air filter ............... Every 100 hours
Change coolant ............... Every 2 years
Valve-lash adjustment ............... Every 1000 hours
Injector inspection ............... Every 1000-1500 hours
Compression test ............... Every 2000 hours
Drain water separator ............... As required
Belt inspection ............... As required

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ................ 5.400-5.402 (137.16-137.21)
Crankshaft Journal Outside Diameter, in (mm) ................ 4.7500-4.7512 (120.650-120.680)
Crank Pin Outside Diameter, in (mm) ................ 3.5000-3.5012 (88.900-88.930)
Crankshaft End Play, in (mm) ................ 0.005-0.021 (0.13-0.53)
Intake Valve Stem Outside Diameter, in (mm) ................ 0.3715-0.3725 (9.436-9.462)
Exhaust Valve Stem Outside Diameter, in (mm) ................ 0.3705-0.3715 (9.411-9.436)
Intake Valve Guide Inside Diameter (Installed), in (mm) ................ 0.3735-0.3745 (9.487-9.512)
Exhaust Valve Guide Inside Diameter (Installed), in (mm) ................ 0.3735-0.3745 (9.487-9.512)
Intake Valve Stem to Guide Clearance, in (mm) ................ 0.0010-0.0030 (0.025-0.076)
Exhaust Valve Stem to Guide Clearance, in (mm) ................ 0.0020-0.0040 (0.051-0.102)
Intake Valve Spring Free Length, in (mm) ................ 2.49 (63.2)
Exhaust Valve Spring Free Length, in (mm) ................ 2.49 (63.2)
Intake Cam Height, in (mm) ................ 2.285-2.297 (58.04-58.34)
Exhaust Cam Height, in (mm) ................ 2.245-2.257 (57.02-57.32)
Piston Pin Outside Diameter, in (mm) ................ 2.0000-2.0004 (50.800-50.810)
Piston Pin to Piston Bore Clearance, in (mm) ................ 0.0004-0.0012 (0.010-0.030)
Top Ring Side Clearance, in (mm) ................ 0.0035-0.0055 (0.089-0.140)
Second Ring Side Clearance, in (mm) ................ 0.0025-0.0045 (0.064-0.114)
Oil Ring Side Clearance, in (mm) ................ 0.0015-0.0035 (0.038-0.089)
Top Ring End Gap, in (mm) ................ 0.0200-0.0340 (0.508-0.864)
Second Ring End Gap, in (mm) ................ 0.0180-0.0300 (0.457-0.762)
Oil Ring End Gap, in (mm) ................ 0.0150-0.0270 (0.381-0.686)

Tightening Torque Specs

Cylinder head bolts ................ 270-310 Nm (199-229 lb-ft)
Main bearing caps ................ 400-450 Nm (295-332 lb-ft)
Connecting rods ................ 155-175 Nm (114-129 lb-ft)
Flywheel bolts ................ 380-420 Nm (280-310 lb-ft)
Crankshaft pulley bolt ................ 450-500 Nm (332-369 lb-ft)
Oil drain plug ................ 50-70 Nm (37-52 lb-ft)
Injector hold-downs ................ 35-45 Nm (26-33 lb-ft)

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• Caterpillar Engines Specs
  
• Cat 3406C Specs
  
• Cat 3406E Specs
  
• Cat 3408 Specs
  
• Cat 3408E Specs
  

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