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The Case 680CK and Its Diesel Legacy
The Case 680CK was a popular construction backhoe-loader introduced in the 1960s and widely used into the 1980s. Built for durability and ease of service, it featured a 301 cubic inch diesel engine paired with a Bosch PES4A injector pump. Case, founded in 1842, became a global leader in agricultural and construction equipment, and the 680CK helped solidify its reputation in the compact backhoe market. Tens of thousands of units were sold across North America, and many remain in use today as reliable workhorses on farms and job sites.
The Bosch PES4A pump is a mechanical inline injection pump with four delivery valves, each feeding one cylinder. It’s known for its robust design and long service life, but like any mechanical system, it can suffer from internal wear, contamination, or component failure—especially after decades of use.
Terminology Notes
In one case, the #2 cylinder on a 680CK stopped receiving fuel. The engine ran on three cylinders, and loosening the injector line at #2 showed no fuel delivery. This ruled out a clogged injector and pointed to a fault inside the pump.
Initial theories included:
Repair Strategy and Step-by-Step Procedure
Operator Anecdotes and Practical Advice
One operator in British Columbia shared that his 680CK had been retired for 20 years but still ran strong until the #2 cylinder failed. After replacing the DV gasket and O-ring, the machine ran like new. He joked that with the extra RPMs, it might start blowing hoses again.
A pump rebuilder in South Carolina recommended always inspecting the DV holder first before assuming internal pump failure. He noted that loose or damaged holders often mimic more serious problems.
Preventive Measures and Recommendations
Fuel delivery issues on a Case 680CK with a Bosch PES4A pump are often caused by minor seal failures rather than catastrophic pump damage. With careful inspection, cleaning, and seal replacement, operators can restore full function without removing the pump. The 680CK’s mechanical simplicity and rugged design make it a forgiving platform for field repairs, and with the right guidance, even first-time pump work can succeed.
The Case 680CK was a popular construction backhoe-loader introduced in the 1960s and widely used into the 1980s. Built for durability and ease of service, it featured a 301 cubic inch diesel engine paired with a Bosch PES4A injector pump. Case, founded in 1842, became a global leader in agricultural and construction equipment, and the 680CK helped solidify its reputation in the compact backhoe market. Tens of thousands of units were sold across North America, and many remain in use today as reliable workhorses on farms and job sites.
The Bosch PES4A pump is a mechanical inline injection pump with four delivery valves, each feeding one cylinder. It’s known for its robust design and long service life, but like any mechanical system, it can suffer from internal wear, contamination, or component failure—especially after decades of use.
Terminology Notes
- Delivery Valve Holder: The threaded cap that secures the delivery valve assembly. It includes an O-ring and copper gasket.
- Rack: A toothed bar inside the pump that adjusts fuel quantity by rotating the plungers.
- Plunger: A precision-machined piston that pressurizes fuel for injection.
- DV (Delivery Valve): A spring-loaded valve that controls fuel flow to the injector line.
In one case, the #2 cylinder on a 680CK stopped receiving fuel. The engine ran on three cylinders, and loosening the injector line at #2 showed no fuel delivery. This ruled out a clogged injector and pointed to a fault inside the pump.
Initial theories included:
- Broken plunger spring
- Seized plunger
- Damaged cam lobe
- Faulty delivery valve gasket
Repair Strategy and Step-by-Step Procedure
- Clean the Area Thoroughly: Use diesel fuel and a brush to remove dirt. Follow with compressed air or ether to dry.
- Remove the Delivery Valve Holder: Carefully unscrew the top nut. Avoid losing the internal spring and volume reducer.
- Inspect the Copper Gasket and O-Ring: Worn or missing seals can prevent proper fuel delivery.
- Replace with OEM Parts: Use Bosch part numbers:
- O-ring: 1 410 210 017
- Copper gasket: 1 410 105 001
- O-ring: 1 410 210 017
- Reassemble and Torque: Tighten the DV holder to 30–35 ft-lbs. Ensure all components are seated correctly.
- Bleed the System: Loosen injector lines and crank the engine to purge air. Retighten once fuel flows.
Operator Anecdotes and Practical Advice
One operator in British Columbia shared that his 680CK had been retired for 20 years but still ran strong until the #2 cylinder failed. After replacing the DV gasket and O-ring, the machine ran like new. He joked that with the extra RPMs, it might start blowing hoses again.
A pump rebuilder in South Carolina recommended always inspecting the DV holder first before assuming internal pump failure. He noted that loose or damaged holders often mimic more serious problems.
Preventive Measures and Recommendations
- Use Clean Fuel: Contaminants accelerate wear in precision components.
- Inspect DV Holders Annually: Look for leaks or signs of loosening.
- Avoid Over-Tightening: Excess torque can distort the copper gasket.
- Keep Spare Seals On Hand: These small parts can prevent major downtime.
- Document Repairs: Note part numbers and torque specs for future reference.
Fuel delivery issues on a Case 680CK with a Bosch PES4A pump are often caused by minor seal failures rather than catastrophic pump damage. With careful inspection, cleaning, and seal replacement, operators can restore full function without removing the pump. The 680CK’s mechanical simplicity and rugged design make it a forgiving platform for field repairs, and with the right guidance, even first-time pump work can succeed.
