Repair of the Cummins QSB4.5 Engine in the Terex RT670-1 Crane

Repair of the Cummins QSB4.5 Engine in the Terex RT670-1 Crane

The rough terrain crane Terex RT670-1 is a robust machine used in demanding construction, industrial, and assembly work conditions. Thanks to its compact design and high mobility in unpaved terrain, it finds wide application where reliability and precision are crucial. In this case, a unit powered by the Cummins QSB4.5 engine in the Tier 4 Interim version came to our service. This engine, known for its fuel efficiency and compliance with stringent emissions standards, required a comprehensive overhaul due to operational issues.

The machine came from a construction site near Katowice, where the operator noticed a drop in power and starting problems. After initial diagnostics, we determined that a detailed verification and rebuilding of the power unit would be necessary. Our mobile service performed the engine disassembly on-site, followed by transport to our workshop in Kojszówka, where we carried out the complete repair process.

Engine Disassembly

The disassembly of the engine from the Terex RT670-1 rough terrain crane was carried out using a crane provided by the client. Our mechanics began by disconnecting the accessories, cooling system, fuel lines, and air intake. All components were properly labeled and secured. After loosening the fasteners and connecting the slings, the Cummins QSB4.5 engine was safely removed from the engine compartment and loaded for transport to our facility.

Verification of Components

After disassembling the unit, we found wear on the crankshaft bearings and connecting rods. This manifested as knocking noises and a drop in oil pressure. During the oil analysis, metal shavings were also detected. The detailed verification included measuring the crankshaft, inspecting the connecting rods, checking the cylinder head for tightness, and testing the injectors on a test bench. The diagnosed damages confirmed the necessity for a comprehensive overhaul.

Regeneration and Repair

The scope of regeneration work included:

• Crank-piston system – replacement of bearings, cylinder liners, pistons, and rings.
• Engine head – machining, replacement of valve guides and valves, leak testing.
• Fuel system – regeneration of the injection pump at a specialized facility, cleaning and testing of injectors.
• Accessories – verification of the turbocharger, alternator, and starter, replacement of worn components.

After completing all regeneration work, the engine was assembled according to the guidelines of Cummins and prepared for testing.

Engine Test on the Dynamometer

One of our key assets is our own engine dynamometer. The Cummins QSB4.5 engine underwent a full cycle of tests, including operation under load for a minimum of 16 hours. Initially, it was tested at a load of 20–30% of nominal power, and then subjected to full loads multiple times. We monitored parameters such as oil pressure, fluid temperature, boost pressure, and cylinder uniformity. This ensured that the unit met factory standards and was ready for further operation.

The dynamometer allows us to eliminate the risk of improper engine operation after installation in the machine. This solution is unique in the construction machinery service industry, building WIBAKO's competitive advantage and providing the client with a quality guarantee.

Engine Installation

After the tests were completed, the engine was delivered back to the construction site in Katowice. The installation process included precise positioning of the unit in the crane frame, connecting the fuel lines, cooling system, and air intake. We also replaced the intake piping and flexible hoses to ensure full tightness and reliability. Next, we performed a trial start-up in the presence of the machine operator. The engine ran smoothly, without leaks or concerning noises. After a series of functional tests, the crane was approved for further operation, and the acceptance protocol was signed jointly with the client.

Engine Maintenance After Overhaul

Every engine we overhaul is covered by a warranty. In the case of the Cummins QSB4.5, we recommended that the client replace the filters after 50 operating hours and check the condition of the connections. Subsequent inspections should be performed every 250 operating hours, but no less frequently than once every 3 months. Our mobile service remains ready to conduct these inspections at the machine's work site.

Machines with the Cummins QSB4.5 Engine

The Cummins QSB4.5 engine finds wide application in off-highway machines. Besides the Terex RT670-1 rough terrain cranes, it can be found in wheel loaders, material handling machines, and other specialized construction vehicles where high efficiency and low operating costs are essential.

Summary

The overhaul of the Cummins QSB4.5 engine in the Terex RT670-1 crane allowed for the complete restoration of the power unit's efficiency and ensured the machine's continued reliable operation. Thanks to comprehensive regeneration, dynamometer testing, and professional installation, the client gained confidence that their equipment would operate reliably in challenging conditions. WIBAKO service offers professional construction machinery service and Cummins diesel engine overhauls, providing technical support at the highest level.

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