1991–1995 Ford 5640, 6640, 7740, 7840, 8240, 8340 & New Holland S90, S100 Tractor Service & Repair Manual (P/N SE 4840-8)

This Ford/New Holland service manual covers the 1991–1995 Ford 5640, 6640, 7740, 7840, 8240 and 8340, plus New Holland S90 and S100 tractors. Publication SE 4840-8 combines the main repair sections with later technical updates.

• Engine and cooling: Diesel engine overhaul, cylinder-head inspection, compression testing, dynamic-balancer service, thermostat checks and water-pump overhaul.

• Fuel and air systems: DPS injection-pump overhaul and bench testing, injector service, turbocharger repair, and dry and wet air-cleaner maintenance.

• Transmissions and PTO: Gearbox overhaul, Dual Power service, Quad Mod clutch calibration, and independent power take-off clutch and control-valve repair.

• Hydraulics and steering: CCLS and fixed-displacement pump testing, Electrolink diagnosis and calibration, lift adjustments, and hydrostatic steering overhaul.

• Axles and brakes: Front and rear axle overhaul, differential adjustment, wet disc brakes, hydraulic trailer brakes, and four-wheel-drive transfer boxes.

• Electrical diagnosis: EIC, AIC and AEIC instrument-cluster testing, alternator and starter-motor overhaul, wiring diagrams, connector references and fault-finding charts.

• Cab and vehicle separation: Cab and platform removal, tractor splitting, air-conditioning diagnosis, and Sanden SD7H15 compressor overhaul.

The overhaul and diagnostic procedures suit experienced tractor technicians equipped for hydraulic pressure testing, electrical fault tracing and work with the specified service tools.

Model References and Build Differences

For Series S tractors, the applicability note maps S90 to the 6640 references and S100 to the 7740 references. Some Series 40 equipment and procedures do not apply to Series S. The S, SL and SLE designations identify Series 40 transmission variants.

Separate EIC, transmission and Electrolink diagnostic sections address revised wiring from Unit Date Code 5L01. Matching these sections to the tractor’s build helps technicians select the appropriate fault charts and connector references before testing components.

Engine and Fuel System Documentation

The engine chapter distinguishes repairs possible with the engine installed from work requiring separation at the front axle or transmission. Cylinder-head, crankshaft, piston, camshaft and crankshaft-driven dynamic-balancer procedures include inspection limits and component-specific torque data. The engine lubrication diagram also shows the oil circuit with a turbocharger fitted.

DPS pump coverage extends beyond priming and hand- and foot-throttle linkage adjustments to internal overhaul, timing, ISO test conditions and model-specific test plans. Pump disassembly, testing and adjustment are reserved for trained personnel using specialized tools and test equipment.

Transmission Overhaul and Clutch Calibration

The transmission chapters cover clutch packs, synchronizers, control valves, pressure tests and applicable calibration routines. Separate procedures address the 8x2 reduction gearbox, both Dual Power assemblies, and the original and Quad Mod versions of the 16x16 transmission.

Dual Power planetary-gear illustrations explain direct-drive and underdrive power flow. C3/C4 clutch assembly instructions identify guide sleeve 4FT 505 and piston pusher 4FT 504; the manual warns that forcing a misaligned piston into its housing can damage the clutch seals.

Hydraulic Systems, Axles and Brakes

Hydraulic coverage distinguishes Closed Center Load Sensing (CCLS) pumps from fixed-displacement gear pumps, with separate sections for top-link sensing and Electrolink. Remote control valves, assist rams and hydraulic trailer-brake valves have dedicated service procedures.

The Tractor and Trailer Brake Layout and SLE hydrostatic-steering component layout support circuit identification. Brake coverage distinguishes mechanical and hydraulic actuation of the wet disc assemblies.

Front-axle chapters cover Carraro 709-ST/709-HD units and New Holland Class 2 and Class 3 axles. The later New Holland axles are not interchangeable with the earlier Carraro designs.

Electrical Fault Finding and Cab Service

Wiring diagrams distinguish cab equipment, instrument-cluster configurations and transmission arrangements. Examples include the SLE main rear harness with cab and EEC IV, plus the later Series 40 upgrade diagrams and electrical connector references.

Air-conditioning coverage includes the original R-12 system and the R134a Sanden SD7H15 compressor. The manual warns against incompatible refrigerants and service equipment and specifies certified A/C technicians for refrigerant-system repairs.

High-pressure hydraulics and tractor separation require the pressure-relief and support precautions described in the manual.

A Preview of Valve-Seat Inspection Data

These valve-seat figures are a small selection of the engine inspection specifications supplied in the manual.

For the covered engines, intake valve-seat width is specified at 0.078–0.098 inches. Valve-seat concentricity relative to the guide bore has a maximum total indicator reading of 0.002 inches. These references accompany the cylinder-head inspection and seat-reconditioning material.

PDF Search, Bookmarks and Wiring Sheets

Search and diagram detail: OCR text search works across the main repair sections, but some wiring labels and the diagram on PDF p. 574 are not searchable. Embedded bookmarks cover the main chapters and electrical appendix. Small wiring labels require zooming; some large-format circuit lines are faint.

Supplied as one printable 1,492-page PDF with English service text and multilingual legends in the electrical appendix. The total already includes the main cover, 14 blank or divider pages, and the 25-page electrical connector and wiring appendix at PDF pp. 1468–1492.