Engine overhaul of Cummins QSB6.7 in Zoomlion ZRT600 all-terrain crane

The all-terrain crane Zoomlion ZRT600 is a modern machine with impressive mobility and off-road capabilities. It is designed to work in challenging construction conditions, where precision and reliability are required. Powered by a Cummins QSB6.7 engine with an output of 194 kW, it features high operational culture, great efficiency, and low fuel consumption. A unit arrived at our service center, where the operator noticed a drop in power and concerning smoke at higher RPMs. After initial diagnostics at the machine's work site, located near Katowice (Silesian Voivodeship), a decision was made to dismantle the power unit and transport it to the WIBAKO headquarters in Kojszówka for full verification and a complete overhaul.

Preliminary diagnostics

During the first stage of checks, symptoms indicating wear of cylinders and pistons were confirmed. A compression test and cylinder leak analysis were conducted, which showed significant differences between the various sections of the engine. Additionally, an endoscopic inspection was performed, revealing signs of wear on the walls of the cylinder liners. The results clearly indicated the need for a complete rebuild of the power unit.

Engine disassembly

The engine disassembly was carried out by our WIBAKO mobile service with the help of a crane provided by the client. All accessory components, cooling system parts, and fuel supply elements were removed. All electrical and hydraulic connections were properly secured, and the engine was transported to our facility. The entire process was conducted in accordance with safety procedures and the technical documentation of the machine's manufacturer.

Verification of components

In the workshop, a detailed verification of all components began. The main issue turned out to be excessive wear of the liners and pistons, as well as scratches on the cylinder surface. The crankshaft underwent runout measurement and visual inspection – no cracks were found, but it required grinding and regeneration of the oil channels. The engine head was subjected to pressure testing and machining. In the fuel system, the injectors were checked on a test bench, which allowed us to determine that two of them required regeneration.

Regeneration and repair

The process of rebuilding the Cummins QSB6.7 engine included the regeneration of the crank-piston system – liners, pistons, rings, and bearings were replaced. The head received new valves and guides, and the fuel system underwent comprehensive servicing at a specialized facility cooperating with us. The accessories – including the turbocharger, alternator, and starter – were checked and regenerated. After assembling the unit, the engine underwent the procedure of setting the timing and adjusting the valve clearances according to the manufacturer's specifications.

Engine dynamometer testing

After the assembly was completed, the engine was moved to our engine dynamometer, where we conducted full load tests. In the first phase, the engine operated under light load conditions for about 16 hours, allowing for the breaking in of new components and assessment of the auxiliary systems' performance. In the next testing phase, the load was gradually increased to nominal values, monitoring oil pressure stability, fluid temperature, and vibration levels. The test results confirmed correct operating parameters – the engine achieved a power output of 194 kW while meeting all exhaust emission standards. Thanks to the dynamometer, we can ensure that every unit leaving our workshop is fully tested and ready for installation in the machine. Our dynamometer is one of the few such stations in Poland dedicated to off-highway engines, which is a significant advantage of the WIBAKO service.

Engine installation

The installation of the engine in the Zoomlion ZRT600 crane was carried out with the utmost precision. Our team of technicians returned the unit to its place, adhering to all manufacturer procedures. During the installation, fuel lines, air intake pipes, and cooling hoses were replaced. The tightness of all connections was checked, and after the installation was completed, the first start-up was performed in the presence of the operator. Thorough operational tests were conducted under various loads, monitoring temperature, pressure, and the operation of the hydraulic system. After the tests were completed, a handover protocol was signed, and the machine was transferred for further operation.

Engine maintenance after overhaul

After the overhaul, we recommend performing the first inspection after 50 operating hours, which includes changing filters and checking the tightness of connections. Subsequent inspections should take place every 250 operating hours or at least every three months. The WIBAKO service offers comprehensive service support and the possibility of conducting inspections on-site with our mobile service.

Cummins QSB6.7 engine – applications

The Cummins QSB6.7 engine is widely used in construction and industrial machines, such as cranes, excavators, loaders, and technological haulers. Due to its compact design, high torque, and great durability, it is a popular choice among manufacturers such as Zoomlion, Terex, and JCB.

Summary

The overhaul of the Cummins QSB6.7 engine in the Zoomlion ZRT600 all-terrain crane was carried out comprehensively, using modern diagnostic tools and our engine dynamometer. Thanks to the professional approach of the WIBAKO service, the machine regained full functionality, and the client gained assurance that their crane would operate reliably for many more seasons. Every engine after overhaul is tested by us and covered by a warranty.

For clients from the Silesian Voivodeship and surrounding areas, we offer quick access to mobile service, professional disassembly, and transport of engines to our workshop in Kojszówka.

What we do as part of the service

What the repair process looks like