Product Type:
Specialized Diesel Engine Service Manual
Value Proposition:
Essential resource for maintaining and repairing David Brown AD4-25 engines, enabling cost savings and ensuring optimal performance and longevity.
Audience:
Mechanics, agricultural machinery technicians, tractor restorers, and owners of equipment powered by the AD4-25 engine.
Engine Mechanical:
Cylinder head, block assembly, crankshaft, pistons, connecting rods, camshaft, valves, timing gears, oil pump, lubrication system.
Fuel System:
Fuel injection pump (Bosch/Simms, specific model dependent), injectors, fuel lines, fuel filters, lift pump, bleeding procedures.
Cooling System:
Radiator, water pump, thermostat, hoses, fan, coolant specifications.
Intake And Exhaust:
Intake manifold, exhaust manifold, air cleaner assembly, turbocharger (if applicable), exhaust system components.
Electrical System:
Starter motor, alternator/generator, battery, wiring diagrams, ignition (if applicable for starting), glow plugs.
Routine Maintenance:
Oil changes, filter replacements, coolant checks, fuel filter changes, air filter servicing, valve adjustments, belt tensioning.
Troubleshooting:
Diagnosis of common problems, fault finding charts, symptom-based troubleshooting for starting, running, and power issues.
Major Overhaul:
Complete engine disassembly, cleaning, inspection, measurement, component replacement, reassembly, and initial run-in procedures.
Component Replacement:
Detailed instructions for replacing specific engine parts like fuel injectors, water pump, oil pump, head gasket, etc.
Testing And Adjustment:
Fuel injection timing, valve clearances, compression testing, cooling system pressure testing.
Depth:
Comprehensive repair and overhaul procedures, suitable for experienced mechanics and dedicated DIY enthusiasts.
Engine Type:
Naturally Aspirated, Four-Stroke Diesel
Configuration:
Inline 4-Cylinder
Displacement:
2.5 Liters (2500 cc)
Bore X Stroke:
Approximately 91.5 mm x 96.5 mm (typical for this displacement and era)
Horsepower:
Around 45-55 HP (Actual output varies by application and tuning, manual will detail specific ratings)
Torque:
Significant torque delivery, crucial for agricultural and industrial applications (specific figures available in manual).
Injection System:
Direct injection, typically with Bosch or Simms inline injection pumps and unit injectors.
Cooling Method:
Water-cooled, typically with a belt-driven fan and thermostat.
Oil Capacity:
Approximately 6-7 Liters (refer to manual for exact specification and filter type).
Glow Plugs:
Equipped with glow plugs for cold starting assistance.
Safety Features In Manual:
Focuses on safe engine operation, maintenance, and repair procedures, including handling of fuels and lubricants.
Engine Related Safety:
Properly functioning fuel system, cooling system, and lubrication are critical for safe operation. Manual addresses these.
Engine Protective Measures:
Engine guarding (if factory fitted) and proper maintenance of components to prevent mechanical failures.
Infotainment Features:
N/A (This manual covers a mechanical engine from a pre-infotainment era of vehicles).
Driver Assistance Features:
N/A (This manual covers a mechanical engine from a pre-driver assistance era of vehicles).
Connectivity Features:
N/A (This manual covers a mechanical engine from a pre-connectivity era of vehicles).
Oil Change Interval:
Typically every 250-500 operating hours, or annually. Manual will provide exact intervals.
Fuel Filter Interval:
Recommended replacement every 500 operating hours or when experiencing fuel delivery issues. Manual will specify.
Air Filter Service:
Regular inspection and cleaning (or replacement if oil bath type) based on operating conditions. Manual details procedure.
Valve Adjustment Interval:
Typically every 500-1000 operating hours. Manual provides precise clearance and procedure.
Engine Oil Grade:
API CD or equivalent, typically SAE 15W-40 or 20W-50 depending on ambient temperature. Consult manual for specific recommendation.
Coolant Type:
Ethylene glycol based antifreeze, mixed 50/50 with distilled water. Manual specifies type and capacity.
Fuel Specification:
Grade 'A' or equivalent Diesel fuel. Manual provides guidance on fuel quality.
Common Wear Points:
Cylinder liners, piston rings, valve seats, camshaft lobes, injection pump timing drift.
Typical Failures:
Glow plug failure, injector nozzle blockage, water pump seal leaks, fuel lift pump malfunction.
Importance Of Filters:
Crucial to maintain clean fuel and oil to prevent wear on injection pump and internal engine components.
David Brown Heritage:
David Brown Tractors Ltd. was a British agricultural machinery manufacturer, known for robust and reliable tractors from the mid-20th century onwards. The AD4-25 engine was a common powerplant for their smaller to mid-range tractors.
Ad4 25 Evolution:
The AD4-25 was a key engine in David Brown's lineup, evolving from earlier designs. It powered various tractor models like the 770, 880, 990, and derivatives, as well as industrial equipment.
Production Period:
Typically manufactured from the late 1950s through the 1970s.
