Reconstruction of Liebherr D9508 A7 Engine in HS 855 HD Crawler Crane

Engine overhaul Liebherr D9508 A7 in HS 855 HD crawler crane

At our company WIBAKO, we carried out a comprehensive overhaul of the Liebherr D9508 A7 engine with a power of 450 kW, which drives the HS 855 HD crawler crane – a specialist duty-cycle machine used mainly in foundation, drilling, and hydrotechnical works. The service work was performed for a client from the Małopolskie Voivodeship, near Kraków. The engine was disassembled on-site by our WIBAKO mobile service, and then transported to the company's headquarters in Kojszówka, where it underwent a complete process of diagnostics, regeneration, and testing on the engine test bench.

Engine disassembly

The disassembly process of the Liebherr D9508 A7 engine began with securing the entire hydraulic and cooling system. WIBAKO mechanics, using a crane provided by the client, disconnected the oil, intake, and exhaust lines. Special attention was paid to properly disconnecting the control systems and sensors to prevent damage. After disconnecting the accessories, the engine was carefully removed from the frame of the HS 855 HD crane and transported to the workshop in Kojszówka.

Verification of components

Initial diagnostics in the machine revealed a drop in oil pressure and noises coming from the lower part of the engine, suggesting wear of the crankshaft bearings. A detailed verification of the crankshaft, connecting rods, pistons, rings, and cylinder liners was carried out in the workshop. Visual inspection and measurements confirmed significant wear of the components of the crank-piston system. The cylinder heads were checked for tightness using a pressure method and showed no cracks. The injection pump and injectors were placed on the test bench, where uneven injection doses were detected.

Regeneration and repair

As part of the crank-piston system repair, the crankshaft was ground and the connecting rods were regenerated. Pistons, rings, liners, and main and connecting rod bearings were replaced. The cylinder heads were machined, and guides and valves were replaced. The injection pump underwent complete regeneration at an authorized partner service, and the injectors were calibrated. The turbochargers and alternator were inspected and bearings were replaced. All components after regeneration were thoroughly cleaned and prepared for assembly.

Engine assembly

After the repair was completed, the D9508 A7 engine was assembled according to the manufacturer's standards. All seals, filters, and operating fluids were replaced. After initial tests on the workshop stand, the engine was reinstalled in the HS 855 HD crane. The assembly process included careful connection of hydraulic, air, and electrical lines. After starting the engine, tests were conducted under the supervision of the machine operator – pressures, temperatures, and system tightness were checked. All parameters were within Liebherr's standards, allowing for the signing of the assembly acceptance protocol.

Test on the engine test bench

One of the key stages of the entire process was the test on the WIBAKO engine test bench. Thanks to this technology, we were able to check the actual operating parameters of the engine under full load before installation in the machine. The test lasted a total of 20 hours, during which the engine operated at 30% of its nominal power for the first 16 hours. Then, the load was gradually increased to 100%, monitoring oil pressure, exhaust temperature, stability of revolutions, and work culture. The test bench also allows for the assessment of the injection system and turbocharger performance under conditions close to real ones. This tool gives our clients the assurance that after installation, the engine will operate smoothly and according to the manufacturer's specifications.

Engine maintenance after overhaul

After the machine was accepted, the client received detailed recommendations regarding engine maintenance after the overhaul. First of all, we recommend performing the first inspection after 50 operating hours, during which our mobile service checks the connections of the lines, the condition of the filters, and any leaks. Subsequent inspections should be carried out every 250 operating hours or every 3 months. Each engine after overhaul at WIBAKO is covered by a warranty and the possibility of further servicing by our team.

Application of the Liebherr D9508 A7 engine

The Liebherr D9508 A7 engine with a power of 450 kW is a V8 unit with high torque, used in heavy construction machines such as HS series crawler cranes, drilling machines, and specialized cranes for hydrotechnical works. Its design ensures durability and high work culture even in difficult terrain conditions.

Summary

The overhaul of the Liebherr D9508 A7 engine in the HS 855 HD crane allowed for the restoration of the machine's full functionality and ensured its long-term, trouble-free operation. Thanks to the tests on the test bench and precise assembly, the client gained confidence in the engine's reliability and work safety. WIBAKO guarantees a comprehensive approach to construction machinery service and diesel engine repair of the Liebherr brand.

Check also

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What the repair process looks like