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Caterpillar C6.6 Engine

The base Caterpillar C6.6 industrial engine (non-ACERT platform, mechanically mirrored by the Perkins 1106 series) is an inline, 6-cylinder, 4-stroke diesel power plant designed for heavy-duty applications. Built for agricultural and construction equipment, this configuration prioritizes simple structural architecture over multi-stage emission modules. This makes the non-ACERT variant highly serviceable in remote environments and less sensitive to variable fuel and lubricant qualities.

The base C6.6 engine relies on an Electronic High-Pressure Common Rail (HPCR) fuel injection architecture managed by an ADEM A4 electronic control module. A low-pressure mechanical transfer pump draws fuel from the supply tank through a primary fuel filter/water separator and a secondary 2-micron fine particulate filter. The conditioned fuel is fed into a high-pressure fuel injection pump, which maintains static high pressure within a shared fuel rail manifold. The engine control unit actuates individual overhead electromagnetic injectors to deliver precise, direct injection timing into each cylinder.

The engine utilizes a force-fed pressure lubrication system pressurized by a crankshaft-driven, gear-type oil pump. Oil is drawn from the pan through a pickup screen, routed through a full-flow spin-on filter, and directed into an integrated fluid-cooled oil cooler. Internal galleries cast into the heavy-duty iron block distribute pressurized oil to the seven main crankshaft bearings, camshaft journals, and the overhead valve train mechanism. Dedicated piston cooling jets are installed at the bottom of each cylinder bore to constantly spray oil onto the under-crown of the pistons to control thermal expansion.

This is a closed-loop, liquid-cooled system utilizing a belt-driven, centrifugal jacket water pump to force coolant through the engine block and cylinder head passages. Temperature regulation is managed by a mechanical thermostat housed in a dedicated cast structure with a vertical outlet. The layout is optimized to prevent localized hot spots around the combustion chambers using standard extended-life coolant mixtures.

General Technical Data

Engine Specifications

Engine Model ............... Caterpillar C6.6
Engine Type ............... 4-cycle 6-cylinder common-rail direct injection ADEM liquid-cooled diesel
Number of Cylinders ............... 6
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 4.13 (105.0)
Engine Stroke, in (mm) ............... 5.00 (127.0)
Displacement, cu.in (L) ............... 403 (6.6)
Rated Engine Power (Construction/industrial), hp (kW) ............... 125-250 (93-186)
Rated Engine Power (Agricultural), hp (kW) ............... 140-225 (104-168)
Rated Engine Power (Generator sets), hp (kW) ............... 122-270 (90-200)
Rated Engine Speed (Construction/industrial), rpm ............... 1800-2400
Rated Engine Speed (Agricultural), rpm ............... 2000-2400
Rated Engine Speed (Generator sets), rpm ............... 1500-1800
Peak Torque ............... 500-900 Nm (369-664 lb-ft) at 1400-1600 rpm
Idle speed ............... 700-800 rpm
Aspiration Type ............... Turbocharged
Compression Ratio ............... 16.0:1 to 17.0:1
Firing Order ............... 1-5-3-6-2-4
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 wet-sump
Oil Pump Type ............... Gear-driven
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 ............... 180-150

Fuel System

Fuel System ............... Common-rail direct injection
Fuel System Control ............... ADEM ECM
Governor Type ............... Electronic
Injection Pressure, bar ............... 1200-1800
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 41-47 (1050-1200)
Overall Width, in (mm) ............... 30-35 (750-900)
Overall Height, in (mm) ............... 37-45 (950-1150)
Dry Weight, lbs (kg) ............... 1257-1500 (570-680)

Maintenance Data

Service Information

Thermostat begins opening ............... 82C (180F)
Thermostat fully open ............... 95C (203F)
Cooling system pressure ............... 70-100 kPa (10-15 psi)
Operating oil pressure ............... 300-450 kPa (44-65 psi)
Idle oil pressure ............... 100-150 kPa (15-22 psi)
Intake Valve Clearance, in (mm) ............... 0.010-0.012 (0.25-0.30)
Exhaust Valve Clearance, in (mm) ............... 0.012-0.014 (0.30-0.35)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CI-4, CJ-4, CK-4
Engine Oil Capacity, qts (L) .................. 14.8-19.0 (14.0-18.0)
Coolant Capacity, qts (L) ............... 21.0-26.0 (20.0-25.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 250-300 hours
Inspect air filter ............... Every 50 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 ............... Every service cycle

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ................ 4.1338-4.1348 (105.000-105.025)
Crankshaft Journal Outside Diameter, in (mm) ................ 3.3067-3.3075 (83.990-84.010)
Crank Pin Outside Diameter, in (mm) ................ 2.8342-2.8350 (71.990-72.010)
Crankshaft End Play, in (mm) ................ 0.0020-0.0150 (0.050-0.380)
Intake Valve Stem Outside Diameter, in (mm) ................ 0.2354-0.2359 (5.979-5.992)
Exhaust Valve Stem Outside Diameter, in (mm) ................ 0.2335-0.2343 (5.931-5.951)
Intake Valve Guide Inside Diameter (Installed), in (mm) ................ 0.2362-0.2371 (6.000-6.022)
Exhaust Valve Guide Inside Diameter (Installed), in (mm) ................ 0.2362-0.2371 (6.000-6.022)
Intake Valve Stem to Guide Clearance, in (mm) ................ 0.0003-0.0017 (0.008-0.043)
Exhaust Valve Stem to Guide Clearance, in (mm) ................ 0.0020-0.0036 (0.050-0.091)
Intake Valve Spring Free Length, in (mm) ................ 2.0700 (52.580)
Exhaust Valve Spring Free Length, in (mm) ................ 2.0700 (52.580)
Intake Cam Height, in (mm) ................ 1.6142 (41.000)
Exhaust Cam Height, in (mm) ................ 1.6142 (41.000)
Piston Pin Outside Diameter, in (mm) ................ 1.5628-1.5630 (39.694-39.700)
Piston Pin to Piston Bore Clearance, in (mm) ................ 0.0002-0.0008 (0.005-0.020)
Second Ring Side Clearance, in (mm) ................ 0.0026-0.0043 (0.065-0.110)
Oil Ring Side Clearance, in (mm) ................ 0.0016-0.0031 (0.040-0.080)
Top Ring End Gap, in (mm) ................ 0.0118-0.0217 (0.300-0.550)
Second Ring End Gap, in (mm) ................ 0.0276-0.0394 (0.700-1.000)
Oil Ring End Gap, in (mm) ................ 0.0138-0.0236 (0.350-0.600)

Tightening Torque Specs

Cylinder head bolts ............... 200-230 Nm (148-170 lb-ft)
Main-bearing caps ............... 260-300 Nm (192-221 lb-ft)
Connecting-rod bolts ............... 110-130 Nm (81-96 lb-ft)
Flywheel bolts ............... 240-280 Nm (177-207 lb-ft)
Crankshaft pulley bolt ............... 300-350 Nm (221-258 lb-ft)
Oil drain plug ............... 40-55 Nm (30-41 lb-ft)
Injector hold-down bolts ............... 25-30 Nm (18-22 lb-ft)

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• Caterpillar Engines Specs
  
• Cat 3054T Specs
  
• Cat 3054 Specs
  
• Cat 3054C Specs
  
• Cat 3054E Specs
  
• Cat 3056 Specs
  
• Cat 3056T Specs
  
• Cat 3056E Specs
  

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