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Doosan D24 Engine

The Doosan D24 (also designated as the DM02 or D24NAP) is a 2.4-liter, 4-cylinder, in-line industrial diesel engine widely utilized in heavy-duty machinery, compact loaders (such as newer Bobcat models), and excavators. Engineered to meet stringent emission standards like Tier 4 and Stage V, it balances a compact footprint with high low-end torque density. The engine relies on a robust cast-iron cylinder block and head, a forged steel crankshaft, and reinforced aluminum pistons. It integrates advanced electronics, common-rail injection, and aftertreatment systems (DOC and DPF) to deliver reliable, high-efficiency performance under variable industrial loads.

The engine employs a vertical overhead valve (OHV) configuration driven by a classic mechanical train consisting of a camshaft, valve tappets, push rods, and rocker arm assemblies. The valves are vertically integrated into the cast-iron cylinder head to optimize gas exchange and thermal efficiency. The cylinder architecture features a bore of 90 mm and a stroke of 94 mm, yielding a total displacement of 2.39 liters. The geometry utilizes a 17.0:1 compression ratio with a standard 1-3-4-2 firing order.

Fuel delivery centers around an electronically controlled Bosch or Delphi Common-Rail Fuel Injection System (CRDI). A high-pressure fuel pump (such as the Delphi DFP 4.4) raises rail pressures up to 1800 bar, feeding precision injection nozzles for highly atomized direct injection. The fuel circuit includes a primary high-efficiency, spin-on full-flow cartridge fuel filter and is metered continuously by the Engine Control Unit (ECU) based on real-time sensor metrics. The system operates strictly on Ultra-Low Sulfur Diesel (ULSD).

Lubrication is managed via a fully forced pressure feed system supplied by a gear-driven oil pump. Oil flows through a replaceable, spin-on full-flow cartridge filter. The system requires heavy-duty API CJ-4 or ACEA-E9 specification engine oils (typically SAE 10W30 for standard operational temperatures). The engine uses a freshwater forced circulation cooling system driven by a centrifugal water pump. A wax-element thermostat controls coolant passage, featuring a valve-opening start temperature of 82C and reaching full open deployment at 97C.

General Technical Data

Engine Specifications

Engine Model ............... Doosan D24
Engine Type ............... 4-cycle inline 4-cylinder direct injection liquid-cooled diesel
Number of Cylinders ............... 4
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 3.54 (90.0)
Engine Stroke, in (mm) ............... 3.70 (94.0)
Displacement, cu.in (L) ............... 146.0 (2.392)
Rated Engine Power, hp (kW) ............... 49.0-74.3 (36.6-55.4)
Rated Engine Speed, rpm ............... 2200-2600
Peak Torque ............... 134.2-236.0 lb-ft (182.0-320.0 Nm) at 1600-1800 rpm
Idle Speed ............... 1150-1220 rpm
Aspiration Type ............... Turbocharged and Intercooled
Operating Speed ............... 2600 rpm
Compression Ratio ............... 17.0:1
Firing Order ............... 1-3-4-2
Valve Mechanism ............... OHV with 2 intake and 2 exhaust valves per cylinder
Crankshaft Rotation ............... Counter-clockwise viewed from flywheel side
Combustion System ............... Direct injection high pressure common rail
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure forced circulation
Oil Pump Type ............... Gear-driven trochoid type
Oil Filter Type ............... Full-flow spin-on cartridge
Cooling System ............... Liquid-cooled with forced circulation water pump
Water Pump Type ............... Belt-driven centrifugal type
Air Cleaner Type ............... Dry dual-element canister type
Emissions Certification ............... Tier 4 Final and Stage V compliant
Aftertreatment System ............... DOC and DPF
Starting System ............... Electric Starter Motor
Electrical System ............... 12V
Alternator Capacity ............... 110A or 140A
Starter Motor Power, hp (kW) ............... 3.35 (2.5)

Fuel System

Fuel Injection Pump Model ............... Delphi DFP 4.4
Fuel Injection Pump Type ............... High pressure common rail injection pump
Max Common Rail Pressure, psi (bar) ............... 26106.0 (1800.0)
Fuel Injector Type ............... Electronically controlled multi-hole solenoid injectors
Fuel Feed Pump Type ............... Mechanical gear type integrated into high pressure pump
Fuel Filter System Type ............... Spin-on cartridge with water separator sensor
Governor Type ............... Full electronic engine management ECU system
Fuel Injection Timing ............... Electronically variable controlled by ECU
Fuel Feed Pump Supply Pressure, psi (bar) ............... 72.5-87.0 (5.0-6.0)
Fuel Grade Requirement ............... Ultra-low sulfur diesel fuel EN590 or ASTM D975
Maximum Fuel Inlet Temperature, F (C) ............... 176.0 (80.0)
Injection Nozzle Opening Pressure, psi (bar) ............... 3625.9 (250.0)
Fuel Tank Vent Requirement ............... Free breathing standard ventilation config
High Pressure Fuel Line Material ............... Thick-walled seamless double-layered steel lines
Fuel Rail Volume, cu.in (cc) ............... 1.22 (20.0)
Number of Injector Spray Orifices ............... 6

Dimensions and Weight

Overall Length, in (mm) ............... 29.5 (750)
Overall Width, in (mm) ............... 22.8 (580)
Overall Height, in (mm) ............... 30.6 (780)
Dry Weight, lbs (kg) ............... 587 (266)
Wet Weight, lbs (kg) ............... 628 (285)

Maintenance Data

Service Information

Oil Pressure at Rated Speed, psi (bar) ............... 43.5-65.2 (3.0-4.5)
Oil Pressure at Low Idle Speed, psi (bar) ............... 14.5-21.7 (1.0-1.5)
Radiator Cap Pressure Rating, psi (bar) ............... 12.78 (0.88)
Turbocharger Maximum Boost Pressure, psi (bar) ............... 20.3-23.2 (1.4-1.6)
Normal Operating Coolant Temp, F (C) ............... 185.0-203.0 (85.0-95.0)
Thermostat Valve Opening Temp, F (C) ............... 179.6 (82.0)
Thermostat Full Open Temp, F (C) ............... 206.6 (97.0)
Maximum Allowable Coolant Temp, F (C) ............... 221.0 (105.0)
Normal Operating Oil Temp, F (C) ............... 194.0-230.0 (90.0-110.0)
Intake Valve Clearance (Cold) , in (mm) ............... 0.0098 (0.250)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.0137 (0.350)

Engine Oil and Coolant

Engine Oil Type .................. SAE 5W-30, SAE 10W-30, or 15W-40
API Service Classifications ......................... CI-4 or CJ-4
Engine Oil Capacity with Filter, qt (L) ............... 9.72 (9.2)
Engine Oil Capacity (Pan Only, High), qt (L) ............... 9.09 (8.6)
Engine Oil Capacity (Pan Only, Low), qt (L) ............... 4.75 (4.5)
Engine Coolant Capacity (Engine Only), qt (L) ............... 3.91 (3.7)

Service Intervals

Change oil and filter ............... Every 500 hours
Inspect air cleaner ............... Every 250 hours
Replace air cleaner ............... Every 1000 hours
Replace fuel filter ............... Every 500 hours
Valve clearance adjustment ............... Every 1000 hours
Fuel system inspection ............... Every 1000 hours
Change coolant ............... Every 2000 hours
Compression test ............... Every 1000 hours
Clean radiator core ............... Every 250 hours
Inspect belt tension ............... Every 200 hours

Service Specifications

Cylinder Bore Inner Diameter, in (mm) ............... 3.5433-3.5441 (90.000-90.022)
Cylinder Bore Maximum, Wear Limit, in (mm) ............... 3.5472 (90.100)
Cylinder Bore Out-of-Round, Limit, in (mm) ............... 0.0007 (0.020)
Cylinder Bore Taper, Wear Limit, in (mm) ............... 0.0007 (0.020)
Crankshaft Main Journal Diameter, in (mm) ............... 2.7547-2.7555 (69.970-69.990)
Crankshaft Main Journal Clearance, in (mm) ............... 0.0015-0.0033 (0.039-0.085)
Crankpin Journal Standard Diameter, in (mm) ............... 2.0854-2.0862 (52.970-52.990)
Crankshaft Rod Journal Wear Limit, in (mm) ............... 2.0830 (52.910)
Crankshaft Rod Journal Clearance, in (mm) ............... 0.0013-0.0031 (0.035-0.081)
Crankshaft Free Axial End Play, in (mm) ............... 0.0035-0.0094 (0.090-0.240)
Connecting Rod Small End Bushing I.D, in (mm) ............... 1.2212-1.2220 (31.020-31.040)
Connecting Rod Big End Side Clearance, in (mm) ............... 0.0039-0.0118 (0.100-0.300)
Main Bearing Shell Thickness, in (mm) ............... 0.0783-0.0787 (1.990-2.000)
Connecting Rod Bearing Shell Thickness, in (mm) ............... 0.0586-0.0590 (1.490-1.500)
Piston Skirt Outer Diameter, in (mm) ............... 3.5401-3.5409 (89.920-89.940)
Piston to Cylinder Bore Clearance, in (mm) ............... 0.0023-0.0039 (0.060-0.102)
Piston Pin Bore Inner Diameter, in (mm) ............... 1.2206-1.2210 (31.005-31.015)
Piston Pin Outer Diameter, in (mm) ............... 1.2198-1.2202 (30.985-30.995)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0003-0.0011 (0.010-0.030)
Piston Pin to Small End Bushing Clearance, in (mm) ............... 0.0009-0.0021 (0.025-0.055)
Top Ring Groove Width, in (mm) ............... 0.0807-0.0815 (2.050-2.070)
Second Ring Groove Width, in (mm) ............... 0.0649-0.0657 (1.650-1.670)
Oil Ring Groove Width, in (mm) ............... 0.1189-0.1197 (3.020-3.040)
Top Ring Side Clearance, in (mm) ............... 0.0027-0.0043 (0.070-0.110)
Second Ring Side Clearance, in (mm) ............... 0.0019-0.0035 (0.050-0.090)
Oil Ring Side Clearance, in (mm) ............... 0.0011-0.0027 (0.030-0.070)
Top Ring End Gap, in (mm) ............... 0.0098-0.0157 (0.250-0.400)
Second Ring End Gap, in (mm) ............... 0.0137-0.0216 (0.350-0.550)
Oil Ring End Gap, in (mm) ............... 0.0098-0.0196 (0.250-0.500)
Cylinder Head Distortion Face Flatness, in (mm) ............... 0.0019 (0.050)
Cylinder Block Top Surface Flatness, in (mm) ............... 0.0019 (0.050)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.2736-0.2742 (6.950-6.965)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.2724-0.2730 (6.920-6.935)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0009-0.0023 (0.025-0.060)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0021-0.0035 (0.055-0.090)
Valve Guide Inner Diameter, in (mm) ............... 0.2751-0.2759 (6.990-7.010)
Intake Valve Sink Depth, in (mm) ............... 0.0275-0.0374 (0.700-0.950)
Exhaust Valve Sink Depth, in (mm) ............... 0.0275-0.0374 (0.700-0.950)
Intake Valve Margin Thickness, in (mm) ............... 0.0393 (1.000)
Exhaust Valve Margin Thickness, in (mm) ............... 0.0393 (1.000)
Intake Valve Seat Angle, deg ............... 45
Exhaust Valve Seat Angle, deg ............... 45
Valve Spring Free Length, in (mm) ............... 1.889 (48.00)
Camshaft Journal Outer Diameter, in (mm) ............... 1.9669-1.9677 (49.960-49.980)
Camshaft Journal Bearing Clearance, in (mm) ............... 0.0007-0.0027 (0.020-0.070)
Camshaft Axial Free End Play, in (mm) ............... 0.0027-0.0078 (0.070-0.200)
Cam Lobe Height (Intake), in (mm) ............... 1.6259-1.6338 (41.300-41.500)
Cam Lobe Height (Exhaust), in (mm) ............... 1.6417-1.6496 (41.700-41.900)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.7472-0.7480 (18.980-19.000)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.7488-0.7496 (19.020-19.040)
Rocker Arm Bushing to Shaft Clearance, in (mm) ............... 0.0007-0.0023 (0.020-0.060)
Tappet Stem Outer Diameter, in (mm) ............... 0.4704-0.4712 (11.950-11.970)
Tappet Guide Bore Inner Diameter, in (mm) ............... 0.4724-0.4736 (12.000-12.030)
Tappet to Guide Bore Clearance, in (mm) ............... 0.0011-0.0031 (0.030-0.080)
Idler Gear Shaft Outer Diameter, in (mm) ............... 1.3381-1.3389 (33.990-34.010)
Idler Gear Bushing Inner Diameter, in (mm) ............... 1.3397-1.3409 (34.030-34.060)
Idler Gear Bushing to Shaft Clearance, in (mm) ............... 0.0007-0.0027 (0.020-0.070)

Tightening Torques

Cylinder Head Fastener (Step One), lb-ft (Nm) ............... 28.9 (39.2)
Cylinder Head Fastener (Step Two), Rotation ............... 90+90 deg
Main Bearing Cap Fastener (Step One), lb-ft (Nm) ............... 36.1 (49.0)
Main Bearing Cap Fastener (Step Two), lb-ft (Nm) ............... 72.3 (98.0)
Main Bearing Cap Fastener (Step Three), lb-ft (Nm) ............... 144.6 (196.1)
Connecting Rod Cap Fastener, lb-ft (Nm) ............... 14.4 (19.6)
Crankshaft Pulley Main Fastener, lb-ft (Nm) ............... 86.8-101.2 (117.6-137.2)
Flywheel Mounting Fastener, lb-ft (Nm) ............... 54.2 (73.5)
Cylinder Head Cover Fixing Screw, lb-ft (Nm) ............... 5.7 (7.8)
Fuel Injector Fixing Bracket Fastener, lb-ft (Nm) ............... 35.0 (47.5)
Common Rail Unit Mounting Fastener, lb-ft (Nm) ............... 16.2 (22.0)
High Pressure Fuel Line Union Nuts, lb-ft (Nm) ............... 21.6 (29.4)
Fuel Injection Pump Drive Gear Fastener, lb-ft (Nm) ............... 21.6-28.9 (29.4-39.2)
Oil Pan Drain Plug, lb-ft (Nm) ............... 21.6 (29.4)
Oil Pan Perimeter Mounting Screws, lb-ft (Nm) ............... 7.2 (9.8)
Water Pump Assembly Mounting Bolt, lb-ft (Nm) ............... 16.2 (22.0)
Thermostat Housing Assembly Fastener, lb-ft (Nm) ............... 16.2 (22.0)
Exhaust Manifold Retention Nuts, lb-ft (Nm) ............... 25.3 (34.3)
Intake Manifold Retention Bolts, lb-ft (Nm) ............... 16.2 (22.0)
Turbocharger Oil Feed Hollow Screw, lb-ft (Nm) ............... 10.8 (14.7)
Turbocharger Oil Return Flange Bolt, lb-ft (Nm) ............... 7.2 (9.8)
Turbocharger Exhaust Mounting Flange Nut, lb-ft (Nm) ............... 16.6 (22.5)
Glow Plug Main Body, lb-ft (Nm) ............... 5.7 (7.8)
Glow Plug Electrical Terminal Nut, lb-ft (Nm) ............... 1.8 (2.4)
Rocker Arm Adjuster Locknut Screw, lb-ft (Nm) ............... 10.8 (14.7)
Rocker Arm Shaft Bracket Fastener, lb-ft (Nm) ............... 25.3 (34.3)
Camshaft Thrust Plate Screw, lb-ft (Nm) ............... 7.2 (9.8)
Timing Gear Case Cover Outer Fastener, lb-ft (Nm) ............... 7.2 (9.8)
Timing Gear Case Inner Plate Fastener, lb-ft (Nm) ............... 16.2 (22.0)
Oil Pressure Sensor Adapter Fitting, lb-ft (Nm) ............... 5.0 (6.8)
Coolant Temperature Sensor, lb-ft (Nm) ............... 14.4 (19.6)
Crankshaft Position Sensor Screw, lb-ft (Nm) ............... 5.0 (6.8)
Camshaft Position Sensor Fastener, lb-ft (Nm) ............... 5.0 (6.8)
Engine Control Unit Mounting Screw, lb-ft (Nm) ............... 7.2 (9.8)
Alternator Mounting Pivot Long Bolt, lb-ft (Nm) ............... 36.1 (49.0)
Alternator Adjusting Strap Lock Bolt, lb-ft (Nm) ............... 16.2 (22.0)
Starter Motor Flange Retaining Nut, lb-ft (Nm) ............... 36.1 (49.0)
Flywheel Housing Perimeter Fastener, lb-ft (Nm) ............... 36.1 (49.0)
Oil Pump Assembly Retention Screws, lb-ft (Nm) ............... 16.2 (22.0)
Oil Relief Valve Plug Component Body, lb-ft (Nm) ............... 28.9 (39.2)
Oil Filter Head Bracket Bolt In Block, lb-ft (Nm) ............... 25.3 (34.3)
Fuel Filter Head Bracket Mounting Screw, lb-ft (Nm) ............... 16.2 (22.0)
Breather Assembly Mounting Cap Screws, lb-ft (Nm) ............... 7.2 (9.8)
Front Engine Lifting Hook Bracket Bolt, lb-ft (Nm) ............... 25.3 (34.3)
Rear Engine Lifting Hook Bracket Bolt, lb-ft (Nm) ............... 25.3 (34.3)
Fan Pulley Assembly Retention Hub Bolts, lb-ft (Nm) ............... 7.2 (9.8)
Belt Tensioner Bracket Retaining Bolt, lb-ft (Nm) ............... 36.1 (49.0)
Air Intake Tube Clamps High Tightness, lb-ft (Nm) ............... 3.6 (4.9)
Exhaust Pipe Connecting Flange Studs, lb-ft (Nm) ............... 36.1 (49.0)
Crankcase Oil Strainer Pickup Tube Bolt, lb-ft (Nm) ............... 7.2 (9.8)
Main Bearing Cap Side Alignment Fastener, lb-ft (Nm) ............... 25.3 (34.3)
Piston Cooling Oil Jet Nozzle Screws, lb-ft (Nm) ............... 7.2 (9.8)
Fuel Injection Pump Mount Stud Flange, lb-ft (Nm) ............... 16.2 (22.0)
Common Rail High Pressure Sensor Thread, lb-ft (Nm) ............... 25.3 (34.3)
Common Rail Pressure Limiter Valve Body, lb-ft (Nm) ............... 50.6 (68.6)
EGR Valve Mounting Retention Fastener, lb-ft (Nm) ............... 16.2 (22.0)
EGR Cooler Mounting Structural Bolts, lb-ft (Nm) ............... 16.2 (22.0)
EGR Gas Pipe Flange Coupler Screws, lb-ft (Nm) ............... 7.2 (9.8)
DOC Housing Clamp V-Band Nut Thread, lb-ft (Nm) ............... 10.8 (14.7)
DPF Sensor Bracket Retaining Bolt, lb-ft (Nm) ............... 7.2 (9.8)
Exhaust Gas Temp Sensor Thread In Boss, lb-ft (Nm) ............... 21.6 (29.4)
Differential Pressure Sensor Tube Nut, lb-ft (Nm) ............... 10.8 (14.7)
Flywheel Housing Access Hole Cover Bolt, lb-ft (Nm) ............... 5.7 (7.8)
Crankshaft Front Oil Seal Screw, lb-ft (Nm) ............... 7.2 (9.8)
Crankshaft Rear Oil Seal Screw, lb-ft (Nm) ............... 7.2 (9.8)
Water Inlet Pipe Flange Sealing Bolt, lb-ft (Nm) ............... 16.2 (22.0)
Water Outlet Pipe Flange Sealing Bolt, lb-ft (Nm) ............... 16.2 (22.0)
Thermostat Cover Sealing Cap Fastener, lb-ft (Nm) ............... 7.2 (9.8)
Oil Cooler Housing Core Mounting Screw, lb-ft (Nm) ............... 7.2 (9.8)
Oil Cooler Assembly Cover Bracket Bolt, lb-ft (Nm) ............... 16.2 (22.0)
Dipstick Guide Tube Lock Bracket Screw, lb-ft (Nm) ............... 7.2 (9.8)
Fuel Low Pressure Supply Line Hollow Bolt, lb-ft (Nm) ............... 18.0 (24.5)
Fuel Low Pressure Return Line Hollow Bolt, lb-ft (Nm) ............... 18.0 (24.5)
Injector Wire Harness Connector Nut Terminal, lb-ft (Nm) ............... 1.1 (1.5)
Cylinder Block Heater Element Bore Plug, lb-ft (Nm) ............... 25.3 (34.3)
Main Sealing Gallery Threaded Core Plugs, lb-ft (Nm) ............... 21.6 (29.4)
Cylinder Head Small Sealing Side Plugs, lb-ft (Nm) ............... 14.4 (19.6)
Vibration Damper Outer Ring Shield Screw, lb-ft (Nm) ............... 7.2 (9.8)
Intake Air Heater Grid Element Power Terminal, lb-ft (Nm) ............... 2.9 (3.9)
Intake Air Heater Housing Mounting Bolt, lb-ft (Nm) ............... 16.2 (22.0)
Alternator Rear Shield Housing Nut Thread, lb-ft (Nm) ............... 3.6 (4.9)
Starter Solenoid Terminal B Threaded Nut, lb-ft (Nm) ............... 7.2 (9.8)
Starter Solenoid Terminal S Small Screw, lb-ft (Nm) ............... 1.8 (2.4)
Engine Ground Cable Block Attachment Bolt, lb-ft (Nm) ............... 36.1 (49.0)

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• Doosan Engines Specs
  
• Doosan D18 Specs
  
• Doosan DL02 Specs
  
• Doosan DL03 Specs
  
• Doosan DM02P Specs
  
• Doosan DM02VB Specs
  

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