Model Variant:
90 and 108 commercial vehicles
Vehicle Type:
Commercial truck / bus chassis
Production Years Covered:
Mid-1930s to 1950s (varies by variant and market)
Manual Title:
Thornycroft 90 108 Engine Owner User Maintenance Manual
Manual Type:
Owner, user and maintenance manual
Applicable Engine:
Thornycroft 90 and 108 engine types
Intended Users:
Owners, operators, fleet maintenance technicians
Target Audience:
Commercial operators, fleet owners and maintenance personnel
Vehicle Class:
Medium to heavy commercial vehicle chassis
Primary Use:
Goods haulage, passenger transport and specialist body applications
Engine Design:
Robust Thornycroft diesel and petrol engine options
Serviceability:
Straightforward mechanical layout suited to workshop maintenance
Parts Availability:
Common service items widely supported in period
Durability:
Heavy-duty construction for continuous commercial duty
Chassis:
Rigid commercial chassis designed for body mounting
Cooling System:
Engine-driven water pump with belt-driven fan
Lubrication:
Pressure-fed lubrication with full-flow filtration
Fuel System:
Mechanical injection or carburettor depending on engine variant
Engine:
90 and 108 engine overhaul, tune-up and servicing
Fuel System:
Pump, injector or carburettor adjustment and repair
Cooling System:
Radiator, pump, thermostat and fan service
Lubrication System:
Oil pump, filter and pressure circuit
Electrical System:
Charging, starting, lighting and ignition (petrol units)
Page Count:
Approximately 80-120 pages (varies by edition)
Delivery Method:
Instant download
Searchable Text:
Yes, with bookmarks where available
Engine Mechanical:
Cylinder head, block, pistons, connecting rods and crankshaft
Valve Train:
Valve adjustment, springs, guides and timing drive
Fuel Injection:
Injection pump timing, injector testing and calibration
Carburettor:
Petrol engine mixture and idle adjustment
Cooling System:
Radiator, water pump, thermostat, hoses and fan
Lubrication System:
Oil pump, relief valve, filter and oil lines
Air Intake:
Air cleaner and intake manifold service
Exhaust System:
Manifold, pipework and silencer
Electrical:
Battery, dynamo, starter motor, regulator and wiring
Ignition:
Distributor, coil, leads and spark plugs (petrol versions)
Routine Maintenance:
Daily checks, weekly inspections and periodic servicing
Engine Tune-Up:
Tappet setting, timing and fuel mixture adjustment
Fault Diagnosis:
Troubleshooting charts for starting, running and overheating
Component Removal:
Step-by-step removal and refitting of major assemblies
Overhaul:
Engine strip-down, inspection, measurement and rebuild
Specifications:
Torque values, clearances and wear limits where stated
Diagrams:
Exploded views, cross-sections and flow diagrams
Measurements:
Metric and imperial units as published in the original
Wiring Information:
Circuit schematics for charging and starting systems
Part Identification:
Component names and reference numbers where available
Service Kits:
Gasket sets, filter elements and bearing sets
Wear Items:
Clutches, brake linings, belts and hoses
File Format:
PDF (searchable, bookmarked, zoomable)
Compatibility:
Windows, macOS, Linux, iOS, and Android — any device with a PDF reader
Requirements:
A PDF reader application (e.g. Adobe Acrobat Reader, free)
Searchability:
Fully text searchable for fast lookup of any topic
Print Quality:
High-resolution digital pages, printable at full clarity
Binding Type:
N/A — digital download, no physical binding
Paper Type:
N/A — digital download, no physical paper
Engine Family:
Thornycroft 90 and 108 series
Configuration:
In-line four and six cylinder options
Fuel Type:
Diesel and petrol variants
Cooling:
Water-cooled with pump circulation
Power Output:
N/A - exact rating depends on engine variant and tune
Torque Output:
N/A - exact rating depends on engine variant and tune
Governed Speed:
Mechanical governor limits maximum engine speed
Diesel Injection:
Mechanical in-line injection pump with pintle injectors
Petrol Carburation:
Updraft or sidedraft carburettor depending on application
Filtration:
Primary and secondary fuel filters fitted
Fuel Tank:
Chassis-mounted tank with mechanical lift pump
Type:
Manual constant-mesh gearbox
Gear Ratios:
N/A - ratios vary by model and final drive specification
Clutch:
Single dry plate clutch with mechanical linkage
Overdrive:
Not commonly fitted; some variants used two-speed rear axle
Auxiliary Gearbox:
Available on certain heavy-duty chassis applications
Final Drive:
Spiral bevel or worm drive depending on model
Propeller Shaft:
Open tubular shaft with universal joints
Lubrication:
Gear oil filled; level plugs for periodic checking
Wheelbase Options:
Multiple wheelbase lengths offered to suit body type
Overall Length:
N/A - dependent on wheelbase and fitted body
Overall Width:
N/A - dependent on chassis and body configuration
Track Width:
N/A - varies by model and axle specification
Curb Weight:
N/A - varies significantly with wheelbase and body
Gross Vehicle Weight:
N/A - plated rating depends on chassis variant
Payload Capacity:
N/A - determined by body and axle ratings
Ratings and Crash Testing
Crash Test Information:
N/A - pre-dates modern standardized crash testing programs
Braking:
Hydraulic or vacuum-assisted drum brakes on all wheels
Steering:
Mechanical worm and nut or worm and roller steering
Lighting:
Headlamps, side lamps and stop lamps as fitted
Cab Structure:
Steel cab with laminated or toughened glass
Mirrors:
Exterior rear-view mirrors fitted
Occupant Protection:
N/A - no modern restraint systems fitted
Audio System:
N/A - radio optional on later models only
Instrumentation:
Mechanical speedometer, ammeter, oil pressure and temperature gauges
Assistance Systems:
N/A - none fitted; driver operates all controls manually
Starting Aid:
Cold-start enrichment or excess fuel device on diesel units
Daily Checks:
Engine oil level, coolant level, fuel and tyre condition
Weekly Checks:
Battery electrolyte, belt tension and brake adjustment
Periodic Service:
Engine oil and filter change at manufacturer-recommended intervals
Major Service:
Valve clearance, injection timing and clutch inspection
Engine Oil:
Straight mineral oil to period specification; refer to manual grade chart
Coolant:
Water with corrosion inhibitor or ethylene glycol antifreeze
Gearbox Oil:
Heavy-duty gear oil to period specification
Brake Fluid:
Hydraulic mineral or glycol fluid as specified for the system
Grease:
Lithium or calcium-based chassis grease for nipples
Clutch Linings:
Wear accelerated by heavy load and stop-start operation
Brake Linings:
Require regular adjustment and periodic replacement
Fan and Drive Belts:
Tension and condition to be checked regularly
Injectors:
Carbon build-up can affect spray pattern and starting
Cooling System:
Scale and corrosion can reduce radiator efficiency
Manufacturer:
Thornycroft
Founded:
Late 19th century as a commercial vehicle and marine engine builder
Headquarters:
Basingstoke, Hampshire, United Kingdom
Later Ownership:
Became part of the Associated Equipment Company (AEC) group
90 and 108 Introduction:
Developed for medium and heavy commercial duties
Engine Development:
Progressive refinement of diesel and petrol power units
End of Production:
N/A - exact cessation dates vary by variant
Primary Plant:
Basingstoke works, United Kingdom
Market Distribution:
United Kingdom and export markets within the Commonwealth
Commercial Acceptance:
Widely adopted by British haulage and passenger transport operators
Engineering Reputation:
Recognized for robust engine design and serviceability
Heritage Status:
Preserved examples held in commercial vehicle collections
Industry Contribution:
Part of British commercial vehicle manufacturing heritage
Documentation Value:
Manual supports restoration and preservation of period vehicles