Model Spotlight

Case 680G Construction King Backhoe Loader: Specs, Parts & Common Issues

The 680E's direct successor. Produced 1979–1981, the 680G kept the Case 336 cu in (5.5 L) four-cylinder diesel but stepped output up to 88 HP gross with refined induction. Same Borg-Warner T19 four-speed drivetrain as the 680E, plus a substantial hydraulic upgrade to 45 gpm combined flow — the biggest practical-performance improvement of the entire 680 line.

BT

Broken Tractor Editorial Team• Updated May 2026• 8 min read

The Case 680G is the direct successor to the 680E in Case's larger-frame Construction King line. It came to market in 1979 and ran through 1981 before the 680H took over in 1982. Mechanically, the 680G is closely related to the 680E — same Case 336 cu in (5.5 L) four-cylinder diesel, same Borg-Warner T19 four-speed transmission, same outboard-planetary final drives and hydrostatic power steering. The headline changes at the 680G are an output bump (80 HP net to 88 HP gross, 80 HP net) and a substantial hydraulic system upgrade to 45 gpm combined flow.

The hydraulic flow increase is the practical-performance story of the 680G. Going from the 680E's high-20-gpm main flow to the 680G's 45 gpm combined-flow open-center system delivers noticeably faster boom, dipper, loader, and stabilizer cycles under combined functions. For operators moving from a 680E to a 680G, the machine feels meaningfully quicker even though peak engine HP only rose by a handful.

At-a-glance specifications

What the 680G changed from the 680E

Three meaningful changes at the 680G:

• Engine output — same 336 ci 5.5L Case diesel, but recalibrated induction and fuel delivery boost output from 80 HP net to 88 HP gross / 80 HP net.
• Two-section hydraulic pump — the 680G uses a main pump plus an auxiliary pump configuration. Main pump 27.2 gpm, auxiliary 17.8 gpm, combined 45 gpm. This is a substantial increase from the 680E's mostly-single-pump arrangement.
• Operating weight envelope — production weight grew to 15,145 – 17,040 lb depending on configuration, reflecting structural updates to the loader frame and backhoe iron to handle the increased hydraulic power.

What did NOT change: the engine block itself, the Borg-Warner T19 transmission, final drives, steering, and most of the cab and operator-station hardware. That's why the L72507 radiator and L55247 main hydraulic pump both cross-fit between the 680E and 680G.

The combined-flow hydraulic system

The 680G's 45 gpm combined-flow hydraulic system is the practical-performance upgrade that distinguishes the machine from its predecessor. Open-center architecture meant the pump delivers flow continuously regardless of whether a function is being commanded — but the combined-flow design means that when the operator does demand flow, two pumps' worth of oil is available.

The functional outcome: boom and dipper cycles are quicker under combined backhoe operations, the loader lifts faster under heavy buckets, and the stabilizers extend and retract noticeably faster. The trade-off is increased parasitic load on the engine — but with the 88 HP rating, the 680G has the power to spare.

Borg-Warner T19 transmission

Same Borg-Warner T19 four-speed manual transmission as the 680E. The T19 in the 680G is configured with a power shuttle hookup that allows hydraulically actuated forward/reverse without the operator working the clutch on every direction change — a useful refinement for backhoe trenching where rapid F/R cycles are routine.

Parts we carry

The 680G is over 40 years old. Parts availability is moderate, helped by cross-fit with the 680E and (for some items) the later 680H, 680K, and 680L. The items below are available at Broken Tractor with verified 680G fitment.

Common issues and what to expect

336 ci engine head and gasket wear

Same family as the 680E engine; same age-related issues. Pre-combustion chamber cracks, head gasket failures, and warping from past overheating events are all expected. Plan on a full top-end rebuild on any unrestored 680G.

Two-section hydraulic pump wear

The two-section pump architecture introduces an additional wear item compared to the single-pump 680E. Symptoms of partial failure: one function (boom, for example) is noticeably weaker than another (dipper) — that's a sign that one pump section has lost capacity while the other is still strong. The L55247 covers the main section.

T19 transmission wear

Synchronizer wear (hard shifting), input shaft bearing failure (whining), and main shaft spline wear are the routine items.

Hydraulic cylinder seal failure

Every cylinder on a 680G has seals that are 40-plus years old. Plan on rebuilding every cylinder as part of any restoration.

Outboard planetary final drive wear

The outboard planetary final drives are durable but have wear points at the planet gear pinions and the planet carrier bearings. Symptoms: clicking under load, oil weeps at the hub seals, or noticeable bearing rumble. Service involves dropping the wheel and inspecting the planet carrier.

Where it sits in the 680 family

The 680G is the late-1970s sibling of the 680E — same chassis architecture but with a substantial hydraulic upgrade. After 1981 the 680H took over with further refinements; then the 680K and 680L closed out the line through the 1980s and 1990s. The 680 family as a whole occupied Case's larger-frame Construction King slot above the 580 line.