Overhaul of Cummins QSB6.7 Engine (119 kW) in Dressta TD-14R Crawler Dozer

Introduction - Servicing the Dressta TD-14R Dozer with Cummins Engine

The Dressta TD-14R crawler dozer is a machine designed for heavy earthmoving, land leveling, and infrastructure projects. For years, the Dressta brand has been associated with durable designs for demanding conditions, and the TD-14R model is valued for its robust undercarriage, high tractive force, and simple, proven construction.

The power unit of this machine is the Cummins QSB6.7 engine with an output of 119 kW. It is a six-cylinder turbocharged diesel engine used in many types of construction machinery. Cummins QSB series engines are known for their operational flexibility, high torque at low speeds, and durability; however, under intensive use, they also require professional servicing.

Our construction machinery service received a report from the Silesian Voivodeship, near Katowice. The operator reported a power drop, increased oil consumption, and distinct blue smoke under load. Initial diagnostics indicated wear on the cylinders and pistons, manifested by reduced compression and blow-by into the crankcase.

Initial On-Machine Diagnostics

Our mobile service arrived at the Dressta TD-14R worksite. We performed basic measurements: compression pressure checks, crankcase breather blow-by analysis, and oil consumption assessment. A cylinder leak test and an evaluation of operating parameters under load were also conducted.

The results confirmed a significant drop in compression on two cylinders. Additionally, an endoscopic inspection of the cylinder interiors revealed visible scratches and signs of liner wear. Based on this, the decision was made to remove the Cummins QSB6.7 engine and transport it to our headquarters in Kojszówka for full verification.

Removal of the Cummins QSB6.7 Engine

The engine removal was carried out by our mechanics using a crane provided by the client. The process involved disconnecting the electrical system, fuel lines, cooling system, and air intake. We paid particular attention to securing the pressure lines and auxiliary components.

After disconnecting the clutch and engine mounts, the engine was safely lifted from the machine frame. The entire unit was properly secured for transport and then moved to our workshop, where detailed verification began.

Workshop Engine Verification

Upon disassembling the Cummins QSB6.7 engine, wear on the cylinder liners and pistons was confirmed. Verification of the crank-piston system included measuring the crankshaft, inspecting main and connecting rod journals, checking oil galleries, and evaluating the bearings.

Cylinder head verification included inspecting valve seats, valve clearances, and a pressure test performed by submerging the head in heated water and applying compressed air. The head showed no cracks but required regeneration due to wear on the valve guides.

Engine Regeneration and Repair

The crank-piston system underwent a comprehensive rebuild. New cylinder liners, pistons, and piston rings were installed. The crankshaft was ground, and appropriate oversized bearings were selected. The connecting rods were checked for twists or bends.

The cylinder head underwent resurfacing, and the guides and valves were replaced. The injectors were tested on a test bench, and the turbocharger was verified for longitudinal and lateral play. The entire unit was reassembled according to the manufacturer's documentation and specified tightening torques.

Engine Dyno Testing

After assembly, the Cummins QSB6.7 engine was mounted on our engine dynamometer (dyno). This is one of the key stages that sets WIBAKO apart from other companies offering Cummins diesel engine service. As one of the few companies in Poland, we possess a test stand that allows for full load testing before the engine is reinstalled in the machine.

The engine ran for a minimum of 16 engine hours at a load of approximately 20-30% of nominal value. During this time, we monitored coolant temperature, oil pressure, combustion parameters, and RPM stability. After initial break-in, the engine was repeatedly subjected to full load to check its behavior under maximum power conditions.

The dyno allows us to detect any potential leaks, fuel system irregularities, or turbocharger issues before the unit returns to the dozer. Consequently, the client receives a proven and tested engine, and the risk of further machine downtime is minimized.

Installation of the Engine in the Dressta TD-14R Dozer

Following the successful completion of the tests, we proceeded with the installation of the engine in the machine. Our mobile service returned to the client's site. Installation involved the precise seating of the engine in the compartment, mounting the engine brackets, connecting the clutch, and carefully reconnecting the fuel and electrical systems.

Filters were replaced, the intake and cooling systems were checked for leaks, and an initial startup was performed in the presence of the operator. After conducting load tests and confirming the absence of leaks, the installation protocol was signed.

Post-Overhaul Maintenance and QSB6.7 Unit Applications

The overhauled Cummins QSB6.7 engine is covered by a warranty. We recommended the first filter change after 50 engine hours, along with an inspection performed by our service team. Subsequent inspections should take place every 250 engine hours, or at least every 3 months.

The QSB6.7 unit is used not only in Dressta dozers but also in wheel loaders, motor graders, and other construction machinery. As a result, we have extensive experience in repairing and regenerating this specific engine model.

Summary

The comprehensive overhaul of the Cummins QSB6.7 engine in the Dressta TD-14R crawler dozer restored the machine's full functionality and eliminated the problems of excessive oil consumption and power loss. Thanks to engine dyno testing and professional installation, the client received a unit fully prepared for further intensive operation.

If you are interested in construction machinery service, or the overhaul or regeneration of a Cummins engine - contact WIBAKO. We perform removals and installations throughout Poland and provide full technical support after the repair.