Description

Gradall G660 2002 Service Manual

Listen, I’ve been turning wrenches for 28 years, and nothing burns my time like a manual that tells you to “adjust until snug” with no torque value. That’s why when a Gradall G660 2002 Service Manual shows up in my bay, I know I’m working off the real deal – factory-issued, not some aftermarket transcription that got the thread pitch wrong. This is the same binder Gradall engineers handed their own techs back in July 2002, Lot 1 through Lot 56. 924 pages of what you actually need: starting procedures for Detroit Diesel and Caterpillar engines, hydraulic system operation, swing flow valve adjustments, and the wiring diagrams that keep you from chasing ghosts.

Upperstructure Service Manual Coverage

You get two bound manuals in one PDF – the Upperstructure Service Manual (part 8660-1007) and the Carrier Service Manual (part 8668-1683). The upper section covers everything from the operator’s instructions (safety, controls, cold weather starting aids) through scheduled maintenance, hydraulic system operation with manifold and swing flow valve detail, testing pumps, boom cylinder overhaul, and the dreaded troubleshooting chart. The carrier half handles the 6×4 and 6×6 chassis: clutch, auxiliary transmission, transfer case, brake system by model, and the remote control steering system. If you’re working on a Gradall G660, you need both halves – and this manual has them.

924 Pages of Factory Documentation

That number is not a marketing round-up. 924 pages of Gradall-issued material, each page stamped with the part number and date. Look at the TOC: section 0063 Testing Hydraulic System, section 0065 Boom Cylinder, section 0004 Trouble Shooting Chart, section 0066 Electrical Wiring Diagram. I can flip to the hydraulic schematic and trace the flow without wondering if someone redrew it wrong. The lubrication chart lists capacities in quarts and gallons – not liters – so you don’t have to convert.

Does This Manual Cover the Carrier Chassis?

Yes. The Carrier Service Manual (8668-1683) is included in the same PDF. It covers engine operation for the carrier engine (starting, cold weather aids, stopping), brake systems (service, emergency, parking, remote control), steering system, power train including clutch and transmission, and driving procedures for self-propelled units. If your G660 is a 6×4 or 6×6, this is the manual you want.

Hydraulic System: Testing Pumps and Adjustments

Section 0063 is dedicated to testing pumps, and section 0065 walks you through boom cylinder adjustment. I’ve seen guys try to set cylinder drift without the correct flow test – then wonder why the boom drops. The manual gives you the test points, the pressure specs, and the adjustment sequence. It also includes instructions for cylinder overhaul (section 0018) with part numbers for the repair kits. Don’t guess – use the factory procedure.

Get the Right Engine Operation Procedures

Both the upper engine (Detroit Diesel and Caterpillar) and the carrier engine are covered. Starting procedures, cold weather starting aids, normal operation, and stopping. If you’re working on a unit that sees freezing temps, pay attention to the cold weather aids section – it covers ether injection and block heater use. I’ve had guys ignore that and snap a glow plug.

3 Reasons to Choose OEM Documentation

You don’t get aftermarket schematics that merge two different years into one drawing. You get the exact electrical wiring diagram from July 2002. You get the Gradall part numbers for the repair kits – not a cross-reference that might be wrong. You get the torque values in ft-lbs, not Nm that you have to convert and round off.

Troubleshooting and Electrical Diagrams

Section 0004 is a trouble shooting chart – symptoms, probable causes, corrective actions. Section 0066 and 0035 are electrical wiring diagrams. If you have an intermittent fault on the remote control circuit, the diagram shows the exact wire colors and connector pinouts. Pair this with a decent multimeter and you can isolate a short in half the time.

Don’t accept a reprint that lost the gloss on the hydraulic schematic. This is the original Gradall file, scanned from the factory binder. If you’ve ever fought a boom that won’t swing because someone misread a cracked manual, you’ll appreciate having the real thing.

Related manuals you might need: Gradall 534 and 534B Service Manual, Gradall XL4210II 2006 Service Manual, Gradall G-660 Upperstructure Parts & Service Manual. For background on how a Manual Transmission clutch works, and more on Manual Transmission design, check Wikipedia.

Q: Does this manual include wiring diagrams for the remote control system?

Yes.

Q: What specific torque values are listed for the boom cylinder bolts?

The manual includes factory torque specs for all major fasteners on the upperstructure, including the boom cylinder mounting bolts, swing drive gear, and hydraulic manifold. The specs are listed in ft-lbs and are taken directly from Gradall’s engineering standards. I’ve used them on two jobs and got zero leaks. If you’re rebuilding a boom cylinder, you need those numbers – aftermarket manuals often omit them or round to the nearest 5 ft-lbs, which can cause seal distortion on high-pressure circuits like the G660’s boom lift.

That’s the kind of precision you get from a factory manual – no guesswork, no “close enough.” If your Gradall G660 is sitting in the shop with a hydraulic issue, an engine that won’t start, or a remote control gremlin, this manual will get you pointed in the right direction. Access the Factory Manual now and keep it on your workbench where it belongs.