Case 688 Excavator: Vintage Legacy Mid-Class Excavator
The Case 688 is a vintage mid-class excavator from the pre-CX era. Durable mechanical-injection diesel power, mechanical hydraulic controls, and a service architecture that still rewards owners who know their way around a wrench and a parts catalog.
Where the 688 fits in the Case excavator line
The 688 is part of Case’s legacy excavator lineage - predecessor to the modern CX-series excavator line. It sits in the mid-class slot of the pre-CX sequence, between the smaller 125B and the larger 880C. These machines came up before Tier 4 emissions, before computerized engine controls became the norm, and before the CX-series brought the platform into the modern era.
Case 688 Excavator - Quick Specs
- Class
- Mid-Class Legacy Excavator
- Era
- Vintage / Pre-CX
- Engine
- Case / Cummins Diesel
- Drivetrain
- Hydrostatic Dual-Path
- Undercarriage
- Steel Track
- Smaller Sibling
- Case 125B
- Larger Sibling
- Case 880C
- Modern Equivalent
- Case CX130
Engine, hydraulics, and drivetrain
The 688 runs a Case or Cummins diesel through a hydrostatic dual-path drivetrain. Pre-Tier 4 emissions - mechanical injection on the earliest builds, electronic engine control on later production. The main hydraulic pump drives boom, dipper, bucket, swing, and propel circuits through mechanical or electrohydraulic control valves. Steel-track undercarriage with the standard pattern of rollers, idlers, drive sprockets, and recoil springs.
This is a machine built before software-driven controls dominated the operator station. Joystick linkages, pedal valves, and the pilot circuit are all serviceable with hand tools and a parts manual - which is exactly why so many of these machines are still in service today.
Common service items on the 688
- Engine internals: Pistons, rings, sleeves, bearings, head gaskets. Mechanical-injection or early-electronic depending on production year.
- Fuel system: Injection pump, injectors, lift pump, primary and secondary fuel filters.
- Cooling system: Radiator, water pump, thermostat, fan, hoses, belts.
- Hydraulic system: Boom, dipper, bucket, and swing cylinder seal kits, main pump rebuild, control valves, hoses.
- Boom and dipper: Pin and bushing service at every joint, bucket pins, thumb attachment hardware, quick coupler service.
- Undercarriage: Steel track inspection and replacement, rollers, idlers, drive sprockets, recoil springs.
- Swing system: Swing motor and reduction gear service, swing bearing inspection, swing brake.
- Electrical: Starter, alternator, wiring harness, gauges, switches.
- Cab glass and wiper: KHN16820 24-inch wiper blade, KHN3046 front lower glass, and KHN2632 front upper glass all cross-fit across Case and Link-Belt excavators.
- Operator station: Seat, joystick controls, pedal linkage, instrument panel, cab HVAC.
Parts and cross-fit components for the Case 688
| Category | Common Parts | Browse |
|---|---|---|
| Engine | Pistons, rings, sleeves, bearings, gaskets | Browse Engine Parts |
| Fuel System | Injection pump, injectors, lift pump, filters | Browse Fuel System |
| Cooling | Radiator, water pump, hoses, belts | Browse Cooling Parts |
| Hydraulics | Main pump, swing motor, cylinders, seal kits, valves | Browse Hydraulics |
| Boom / Dipper | Pins, bushings, bucket and quick-coupler hardware | Browse Boom / Dipper |
| Undercarriage | Steel tracks, rollers, idlers, sprockets, recoil springs | Browse Undercarriage |
| Swing | Swing motor, reduction gear, swing bearing | Browse Swing |
| Cab Glass / Wiper | KHN16820 wiper, KHN3046 lower glass, KHN2632 upper glass (Case/Link-Belt cross-fit) | Browse Cab Glass |
| Electrical | Starter, alternator, harness, gauges | Browse Electrical |
| Operator Station | Seat, joysticks, pedal linkage, gauges | Browse Operator Station |
Need a part for your Case 688 Excavator?
Hydraulic cylinder seal kits, main pumps, swing motors, and undercarriage components are the highest-value items on a 688. Call our parts team with your serial number.
Request a PartWhat to verify before ordering
- Serial number. Confirm the serial on the 688 before ordering year-specific parts. Multiple revisions ran through the production window.
- Engine serial. Engine internal parts must match the engine serial number, not just the chassis serial.
- Hydraulic cylinder bore. Cylinder seal kit fit depends on bore dimension - measure before ordering.
- Production-window revision. Engine and hydraulic components saw multiple revisions during the production run.
- Bucket and quick coupler. Quick-coupler interface varies - confirm before ordering attachment-side hardware.
- Injection system. Earliest 688 builds used mechanical injection; later production moved to electronic engine control. Confirm which system is on your machine before ordering fuel-system components.
Why the 688 still earns a paycheck
The Case 688 is a legacy excavator from the era before the modern CX-series. Pre-Tier 4 emissions, mechanical or early-electronic injection, and service architecture that rewards a wrench, a manual, and a parts catalog. For owners and operators running these machines, parts availability through the legacy Case service network remains broad - and many components cross-fit between Case and Link-Belt excavators of the same era.
Maintenance priorities on a 688: clean fuel and quality filtration, hydraulic oil at temperature with clean filters, swing-bearing lubrication, steel-track tension and undercarriage wear monitoring, and pin and bushing service at every working joint. Broken Tractor maintains parts coverage across the Case legacy excavator family.
