Looking for the factory PDF for your JCB 802.7, 803, or 804 mini-excavator? This 250-page service manual (OEM #9803/3145) spans the full 1994–2005 range: 802.7 Plus, 802.7 Super, 803 Plus, 803 Super, and 804 Plus. Inside are separate hydraulic circuit schematics for the 802.7/803 and 803 Super/804 variants, full wiring harness diagrams, and step-by-step rebuild procedures covering hydraulic pumps, gearboxes, tracks, and the engine from cylinder head to crankshaft. The hydraulic fault chart splits every failure between all-service and single-circuit problems, so your first check points straight to the source. Swap the fuel filter every 500 operating hours or 6 months, tighten the canister hand-tight plus a quarter turn, and you're done. Idle time costs money. Download it once and search by keyword right at the machine, on a phone or tablet.
What's Inside This JCB 802.7, 803, 804 Manual
| System | Pages | Key Topics |
|---|---|---|
| Routine Maintenance | 53-70 | Fluids, Lubricants, Capacities and Specifications, Engine Lubrication Chart, Torque Settings, Hydraulic Fittings, Fuel Systems, Bleeding the Fuel System |
| Optional Equipment | 71 | Cab Working Lights, Double Acting Auxiliary Pipework, 3CX Hand Controller Pattern, Hose Burst Protection Valves, Radio Kit, Long, Standard or Short Dipper, Long or Short Dozer |
| Body & Framework | 72-84 | Bucket Linkage (Removal and Replacement), Bucket Ram Pivot and Linkage (Removal and Replacement), Dipper (Removal and Replacement), Boom (Removal and Replacement) |
| Electrics | 85-111 | Technical Data, Battery, Fan Belt, Alternator, Starter Motor, Beacon, Circuit Diagram, Wiring Harness |
| Controls | 112-113 | Servo Hand Controllers (Description and Operation, Port Identification, Switchable ISO/SAE Mode, Changing the Excavator Control Mode), Track Levers, Dozer Lever |
| Hydraulics | 114-185 | Technical Data, Hydraulic Circuit 802.7 / 803, Hydraulic Circuit 803 Super / 804, Servo Circuit (Description), Hydraulic System, Hydraulic Pump 802.7 / 803 (Operation) |
| Gearboxes | 186-196 | Technical Data, Track Gearbox (Operation, Check Oil Level, Drain and Refill, Removal and Replacement, Dismantling and Assembly), Slew Gearbox (Removal and Replacement) |
| Track & Running Gear | 197-211 | Tracks (Clean and Inspection, Removal and Replacement, Changing), Track Rollers (Removal and Replacement, Dismantling and Assembly) |
| Engine | 212-250 | Technical Data, Engine Oil Drain and Refilling, Oil Filter Renewing, Oil Cooler Removing and Fitting, Oil Pressure Relief Valve Removing and Fitting, Oil Sump |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Metric Grade 8.8 Bolt Torque (M5) | 7 Nm (5 lbf ft) | p. 56 |
| Metric Grade 8.8 Bolt Torque (M6) | 12 Nm (9 lbf ft) | p. 56 |
| Hydraulic Fault Troubleshooting First Step | Is the fault in all services or one only? ALL : Check 2 ONE : Check 6 | p. 124 |
| Fuel Filter Element Replacement Interval | Every 500 operating hours or 6 months whichever occurs first | p. 64 |
| Fuel Filter Canister Tightening | hand tight and then one quarter turn | p. 223 |
| Fuel Sediment Bowl Cleaning Interval | Every 50 operating hours or weekly whichever occurs first | p. 63 |
| Fan Belt Deflection | 5 mm (0.2 in) with approximately 10 N (1 kgf, 0.51 lbf) force | p. 88 |
| Fan Belt Adjustment Interval | Every 50 operating hours or weekly whichever occurs first | p. 63 |
| Battery Voltage | 12V | p. 86 |
| Battery Capacity (Wet charged) | 75 ampere/hour | p. 86 |
| Hydraulic Fluid Return Filter Element Replacement Interval | Every 500 operating hours or 6 months whichever occurs first | p. 64 |
| Track Motor to Undercarriage Torque | 113 Nm (83 lbf ft) | p. 56 |
JCB 802.7, 803, 804 Common Problems This Manual Covers
JCB 802.7 engine cranks but won't start, or misfires after fuel filter service p. 60
Clean the sediment bowl first, and keep doing it every 50 hours. If the engine still won't fire after several cranks, bleed the fuel system using the procedure on pages 60-61: crack the bleed screw, crank until fuel runs bubble-free, then tighten and retry. Renew the fuel filter element every 500 hours, tightening the canister hand-tight plus one quarter turn as noted on page 223.
Manual Section: Fuel SystemsOil pressure warning light stays on after cranking, engine won't clear the lamp p. 213
Confirm the engine oil level before anything else; capacity is 4.5 litres. The warning lamp is normal at key position I before cranking and should go out once oil pressure builds. If it stays lit while cranking, stop immediately. Look for a stuck relief valve or an external leak. At running speed, pressure should read 1.7 to 4.1 bar (25-60 lbf/in2) per page 213.
Manual Section: EngineFan belt squeals or slips, alternator not charging, timing case cover rattling p. 88
Inspect belt condition and measure deflection: correct tension is 5 mm (0.2 in) under roughly 10 N (1 kgf) finger pressure at page 88. A belt run too loose will damage the timing case cover, so don't skip this. Adjust every 50 hours or weekly, and replace at the first sign of cracking, fraying, or glazing. Recheck tension after the first few hours on a new belt.
Manual Section: ElectricsHydraulic functions sluggish, bucket lifts slowly, or controls feel unresponsive p. 124
Start with the fault isolation chart on page 124 to tell whether the fault sits in all services or just one. If all services are weak, check the hydraulic oil level first: tank capacity is 48 litres (10.6 UK Gal) on the 802.7 and 803. Warm the system at low idle for several minutes before going further. If only one circuit is slow, trace it to that circuit's relief valve or control valve section.
Manual Section: HydraulicsTracks running loose, skipping over sprocket, or rubber track wearing unevenly p. 201
Measure track sag at the midpoint between the sprocket and front idler. Rubber tracks want 15 mm to 20 mm clearance (page 201); adjust the tensioner until you land in that window. Inspect rollers for flat spots and bearing play, with the roller removal and inspection procedure starting at page 204. Loose tension wears the whole undercarriage, not just the track.
Manual Section: Track & Running GearStarter motor turns slowly or clicks, machine hard to start in cold weather p. 86
Test battery voltage: spec is 12V, with 75 Ah (wet charged) for the 802.7/803 or 103 Ah (wet charged) for the 804 per page 86. A weak battery is the usual cold-start culprit. Check the terminals for corrosion and the cable connections at the starter. If the starter itself looks suspect, bench it against a known-good 12V source as described on page 91. Recharge or replace before digging into the fuel system.
Manual Section: ElectricsFrequently Asked Questions
What should I check first if my JCB 802.7 or 803 engine cranks but will not start after a fuel filter service?
Clean the sediment bowl first, then bleed the fuel system following the priming procedure on page 60 of the service manual.
Why does the oil pressure warning light stay on after cranking the JCB 802.7 or 803?
Confirm the engine oil level is correct, then check the oil pressure sender and switch wiring before suspecting internal wear. The manual covers this diagnostic on page 213.
What causes sluggish hydraulic functions on the JCB 802.7/803/804 and where do I start the diagnosis?
Start with the fault isolation chart in the hydraulic section (page 124), which splits failures between all-circuit and single-circuit causes before you begin dismantling.
What is the torque for the track motor-to-undercarriage fasteners on the JCB 802.7/803?
Track motor to undercarriage: 113 Nm (11.5 kgf m / 83 lbf ft). Track roller: 244 Nm (25 kgf m / 180 lbf ft). Both figures are on page 56.
Document Quality
This PDF is a scanned document with an OCR layer, allowing you to search and copy text throughout. The OCR text is generally crisp and readable, though some original page numbers and headers show minor blurriness. Diagrams and illustrations are raster images, exhibiting some pixelation when magnified, but their labels remain readable. Page condition is mostly clean, with occasional minor scan artifacts and slight skewing on some pages. You will find several pages with minimal content, serving as section dividers or version indicators.
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