John Deere 8120T, 8220T, 8320T, 8420T and 8520T Tracked Tractor Repair Manual (TM1971)

Machines covered

This manual (TM1971, dated 24JUL10) covers the full tracked tractor line: 8120T, 8220T, 8320T, 8420T and 8520T. These run John Deere's PowerTech 8.1L (6081) diesel engine, with Level 9 engines using Denso's high-pressure common rail fuel system (CTM255). Diagnosis and testing are handled in the companion manual, TM1981.

What this manual covers

Because these are tracked machines rather than wheeled, this manual includes an entire section devoted to the track frame itself - tracks, the tension cylinder and accumulator, and the track frame structure - on top of the usual drive, steering, hydraulics and cab coverage you'd expect on a large row-crop tractor.

Table of Contents

• Section 10 - General Information - safety, general information
• Section 20 - Engine - component removal/installation, engine repair
• Section 30 - Fuel and Cooling Systems - diesel fuel system, air intake, engine cooling, A/C condenser
• Section 40 - Electrical - connectors, wiring harness routings, charging/starting circuits, relays/fuses/solenoids/switches, monitoring systems, armrest control, implement connectors, accessories
• Section 50 - Transmission - component removal/installation, in-tractor repair, transmission
• Section 56 - Drive Systems - rear axle, outboard planetary final drive, PTO, steering gears, mid-frame drive shafts
• Section 60 - Steering and Brakes - steering column, wheel position input, steering pump/motor, brake valve and components
• Section 70 - Hydraulics - system repair/cleanup, tandem and secondary hydraulic pumps, filter bypass, hitch valve/SCVs/couplers, hitch
• Section 80 - Miscellaneous - hood
• Section 90 - Operator Station - component removal/installation, HVAC, A/C, air suspension seat, armrest, cab door/windshield
• Section 95 - Track Frame and Components - tracks, tension cylinder/accumulator, track frame
• Section 99 - Dealer Fabricated Tools

Good to know

Also useful alongside this manual: AMS Systems and Components Diagnosis and Tests (TM1909), the GreenStar 2 Diagnosis and Tests manual (TM1061), the Series 450/6081 diesel engine manual (CTM86), and alternators/starters (CTM77). 1015 pages.