________________________________________________________________________________

Caterpillar 3116T Engine

The Caterpillar 3116T is a 6.6-liter, inline 6-cylinder, four-stroke cycle diesel engine featuring a single turbocharger configuration. Introduced in the late 1980s, this engine became a staple in medium-duty trucks, school buses, marine vessels, and heavy industrial machinery. It utilizes a cast-iron "parent-bore" block without wet cylinder liners, which prioritizes rigid structural durability but requires precision machining during an overhaul. Known for its strictly mechanical operation, the 3116T lacks electronic engine management. While it offers excellent power-to-weight performance and high reliability, it demands precise specialized toolsets for top-end timing and fuel synchronization.

The 3116T features a Mechanical Unit Injection (MUI) system. A low-pressure fuel transfer lift pump (integrated with the mechanical governor assembly) draws fuel from the supply tank through a primary water separator and filter. Pressurized fuel is delivered through internal drilled passages inside the cylinder head casting directly into galleries surrounding each mechanical unit injector. Each individual unit injector is operated mechanically by its own rocker arm, pushrod, and dedicated lobe on the engine camshaft. A purely mechanical control rack linkage extends beneath the valve cover to synchronize and meter fuel delivery across all injectors simultaneously. Excess fuel continually cools the injectors and flows past a return line pressure-regulating orifice and check valve back to the fuel tank.

The lubrication system utilizes a gear-driven oil pump that draws engine oil from a wet bottom-sump oil pan. Oil passes through an integrated water-cooled oil cooler before entering a spin-on full-flow oil filter. Internal galleries channel pressurized oil directly to the crankshaft main bearings, connecting rod journals, camshaft bearings, and pushrod rocker assemblies. The refill system capacity for standard configurations is 25.0 liters (6.6 U.S. gallons).

This engine utilizes a liquid-cooled jacket system driven by a centrifugal, gear-driven water pump. Coolant circulates through the engine block jacket and cylinder head to regulate operating temperatures. For marine or high-output industrial setups, the circuit is paired with an expansion tank, an auxiliary sea-water pump, and a heat exchanger. The total operational capacity of the cooling system is 28.0 liters (7.4 U.S. gallons).

General Technical Data

Engine Specifications

Engine Model ............... Caterpillar 3116T
Engine Type ............... 4-cycle inline 6-cylinder turbocharged 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) ............... 402 (6.6)
Rated Engine Power (Truck), hp (kW) ............... 170-250 (127-186)
Rated Engine Power (Industrial), hp (kW) ............... 140-215 (104-160)
Rated Engine Power (Marine), hp (kW) ............... 150-300 (112-224)
Rated Engine Speed, rpm ............... 2200-2600
Peak Torque ............... 700-950 Nm (516-701 lb-ft) at 1400-1600 rpm
Aspiration Type ............... Turbocharged
Operating Speed ............... 2000-2600 rpm
Idle Speed ............... 650-750 rpm
Compression Ratio ............... 16.0:1-17.0:1
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
Oil Pump Type ............... Gear-driven
Oil Filter Type ............... Full-flow, spin-on
Cooling System ............... Liquid-cooled
Water Pump Type ............... Belt-driven, centrifugal
Air Cleaner Type ............... Dry two-stage
Starting System ............... Electric Starter
Electrical System ............... 12V or 24V
Alternator Rating, Amps ............... 55-120

Fuel System

Fuel System ............... Mechanical Unit Injectors (MUI)
Fuel Pump Type ............... Gear-type, transfer
Governor Type ............... Mechanical
Injection Pressure, bar ............... 1000
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 41-45 (1050-1150)
Overall Width, in (mm) ............... 31-35 (780-880)
Overall Height, in (mm) ............... 33.5-35.5 (850-900)
Dry Weight, lbs (kg) ............... 1500 (680)

Maintenance Data

Service Information

Thermostat begins opening ............... 82C (180F)
Thermostat fully open ............... 95C (203F)
Cooling system pressure ............... 70-90 kPa (10-13 psi)
Operating oil pressure ............... 300-450 kPa (44-65 psi)
Idle oil pressure ............... 100-150 kPa (15-22 psi)
Intake Valve Clearance, in (mm) ............... 0.015-0.017 (0.38-0.43)
Exhaust Valve Clearance, in (mm) ............... 0.025-0.027 (0.64-0.69)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CF-4, CG-4, CI-4, or higher
Engine Oil Capacity, qts (L) .................. 27.3-33.6 (25.0-32.0)
Coolant Capacity, qts (L) ............... 29.4 (28.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 500 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 ............... As required

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ................ 4.1348-4.1364 (105.025-105.065)
Crankshaft Journal Outside Diameter, in (mm) ................ 3.4996-3.5004 (88.890-88.910)
Crank Pin Outside Diameter, in (mm) ................ 2.7555-2.7563 (69.990-70.010)
Crankshaft End Play, in (mm) ................ 0.0030-0.0100 (0.076-0.254)
Intake Valve Stem Outside Diameter, in (mm) ................ 0.3130-0.3138 (7.950-7.970)
Exhaust Valve Stem Outside Diameter, in (mm) ................ 0.3122-0.3130 (7.930-7.950)
Intake Valve Guide Inside Diameter (Installed), in (mm) ................ 0.3155-0.3167 (8.013-8.043)
Exhaust Valve Guide Inside Diameter (Installed), in (mm) ................ 0.3155-0.3167 (8.013-8.043)
Intake Valve Stem to Guide Clearance, in (mm) ................ 0.0017-0.0037 (0.043-0.093)
Exhaust Valve Stem to Guide Clearance, in (mm) ................ 0.0025-0.0045 (0.063-0.113)
Intake Valve Spring Free Length, in (mm) ................ 2.463 (62.56)
Exhaust Valve Spring Free Length, in (mm) ................ 2.463 (62.56)
Intake Cam Height, in (mm) ................ 2.6457 (67.200)
Exhaust Cam Height, in (mm) ................ 2.5694 (65.263)
Piston Pin Outside Diameter, in (mm) ................ 1.5746-1.5748 (39.995-40.000)
Piston Pin to Piston Bore Clearance, in (mm) ................ 0.0003-0.0011 (0.008-0.028)
Top Ring Side Clearance, in (mm) ................ 0.0031-0.0047 (0.080-0.120)
Second Ring Side Clearance, in (mm) ................ 0.0024-0.0040 (0.060-0.100)
Oil Ring Side Clearance, in (mm) ................ 0.0016-0.0032 (0.040-0.080)
Top Ring End Gap, in (mm) ................ 0.0157-0.0256 (0.400-0.650)
Second Ring End Gap, in (mm) ................ 0.0098-0.0197 (0.250-0.500)
Oil Ring End Gap, in (mm) ................ 0.0098-0.0197 (0.250-0.500)

Tightening Torque Specs

Cylinder Head Bolts ............... 170-190 Nm (125-140 lb-ft)
Main Bearing Bolts ............... 200-230 Nm (148-170 lb-ft)
Connecting Rod Bolts ............... 110-130 Nm (81-96 lb-ft)
Flywheel Bolts ............... 180-210 Nm (133-155 lb-ft)
Crankshaft Pulley Bolts ............... 350-400 Nm (258-295 lb-ft)
Oil Drain Plug ............... 40-55 Nm (30-41 lb-ft)
Injector Hold-Downs ............... 25-30 Nm (18-22 lb-ft)

________________________________________________________________________________________

• Caterpillar Engines Specs
  
• Cat 3064 Specs
  
• Cat 3064T Specs
  
• Cat 3066 Specs
  
• Cat 3114 Specs
  
• Cat 3116 Specs
  
• Cat 3116TA Specs
  

________________________________________________________________________________

________________________________________________________________________________________

_______________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________