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Caterpillar 3408E Engine

The Caterpillar 3408E is a heavy-duty, four-stroke cycle, 8-cylinder diesel engine configured in a 65-degree V-orientation. The "E" designation marks the integration of advanced electronic controls over its purely mechanical predecessors, utilizing an Electronic Control Module (ECM) to manage critical engine functions, minimize emissions, and optimize fuel-to-air ratios across changing load profiles. Developed for demanding, continuous-duty applications, this engine is primarily deployed in high-capacity earthmoving machinery, industrial power units, oil and gas compression installations, and marine propulsion systems.

It relies on a single or dual-turbocharged air aspiration setup coupled with a water-cooled aftercooler circuit to maximize thermal efficiency and power density. The engine architecture features a physical cylinder bore size of 5.4 inches (137.2 mm) and a piston stroke length of 6.0 inches (152.4 mm). This structural architecture provides a total engine displacement of 1,099 cubic inches (18.0 liters).

The 3408E uses a Hydraulic Electronic Unit Injection (HEUI) fuel system. Unlike conventional camshaft-driven injectors, HEUI injectors utilize highly pressurized engine oil to actuate the fuel injection plungers. The Engine Control Module (ECM) actuates an electronic spool valve on each individual injector, allowing this high-pressure oil to force the injector plunger downward, resulting in precise fuel delivery regardless of engine RPM. The supply side consists of a primary fuel filter water separator, a low-pressure fuel transfer pump, a secondary fuel filter bank, and an integrated fuel pressure regulating check valve.

Lubrication is managed via a high-output, full-pressure internal system driven by a gear-type oil pump. Engine oil is forced through an integrated plate-type water-cooled oil cooler before routing through dual spin-on or high-efficiency cartridge-type oil filters. A dedicated cold start oil reservoir and cool down circuit help prevent component starvation during initial crank cycles. The thermal management system uses a closed-loop, liquid-cooling design driven by a gear-driven centrifugal water pump. Flow control is governed by heavy-duty dual thermostats operating within an optimal regulating threshold of 180 to 210F (82 to 99C). Coolant is directed across the water-cooled exhaust manifolds, engine block jackets, oil cooler core, and the dedicated aftercooler core to dissipate combustion heat.

General Technical Data

Engine Specifications

Engine Model ............... Caterpillar 3408E
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 ............... 14.5:1
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 ............... Electronic Unit Injection (EUI)
Fuel Pump Type ............... Gear-type, transfer
Fuel System Control ............... Digital Electronic Control (ADEC)
Governor Type ............... Electronic
Injection Pressure, bar ............... 1930
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 ......................... CH-4 or CI-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 ............... 300 Nm (221 lb-ft)
Main Bearing Cap Bolts (Vertical) ............... 340 Nm (250 lb-ft)
Main Bearing Cap Cross Bolts ............... 190 Nm (140 lb-ft)
Connecting Rod Bolts ............... 230 Nm (170 lb-ft)
Flywheel Housing-to-Block Bolts ............... 190 Nm (140 lb-ft)
Flywheel-to-Crankshaft Bolts ............... 340 Nm (250 lb-ft)
Unit Injector Clamp Bolt ............... 35 Nm (26 lb-ft)
Oil Pan Bolts ............... 27 Nm (20 lb-ft)

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

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