Repair of Liebherr D9406 TI-E Engine in LR 1400/1 Crawler Crane

Comprehensive repair of the Liebherr D9406 TI-E engine in the Liebherr LR 1400/1 crawler crane

Introduction

The powerful Liebherr LR 1400/1 crawler crane arrived at WIBAKO service, used for demanding lifting tasks, especially during the assembly of steel structures and the implementation of infrastructure projects. The machine is powered by a high-performance Liebherr D9406 TI-E diesel engine, a 6-cylinder unit known for its excellent durability, high operational culture, and long-term load capabilities. The device was brought to our service from the vicinity of Katowice, where the WIBAKO mobile team conducted preliminary diagnostics at the machine's work site.

The owner reported a problem related to a drop in power and irregular engine operation. Additionally, the operator noted difficulties in starting at low temperatures and increased smoke during acceleration. Initial symptoms indicated possible burnt valves in the cylinder head, which is not uncommon in engines operated under high and prolonged loads. Due to the nature of crawler crane operations—often working for many hours under constant load—the cylinder head system is exposed to exceptionally high temperatures.

Preliminary diagnostics in the machine

Upon arrival at the client’s location, preliminary measurements of compression pressure, exhaust gas analysis, and cylinder leak testing were performed. The first results confirmed discrepancies between individual cylinders, indicating a leak in the exhaust valves. Endoscopy confirmed burnt valve seats and visible micro-cracks on one of the valves.

To verify the extent of the damage, it was necessary to disassemble the unit. Due to the size of the machine and the specific design of the LR 1400/1, disassembly required the client to provide a support crane and full coordination with the machine operator.

Engine disassembly

Disassembling the Liebherr D9406 TI-E engine in this type of crawler crane is a complex process that requires proper preparation of the work area, securing all hydraulic lines, and disconnecting the power supply to the control systems. Our technicians disassembled the engine accessories, including the intake system, parts of the cooling system, wiring, protective elements, and fuel connections.

The engine was lifted by the support crane, properly secured, and placed on a special transport frame. From there, it was taken to our headquarters in Kojszówka, where we began a full verification.

Engine verification in the workshop

After preliminary inspections and disassembly of the unit into components, we confirmed our earlier suspicions—the engine head required a complete overhaul. Clear burn marks were found on several valves, and deformation of the mating surface was noted. Additionally, during the inspection of the connecting rod-piston system, visible signs of wear on the cylinder sleeves and increased play on one of the connecting rod bearings were observed.

The scope of work also included:

- verification of the crankshaft (measuring journals, checking runout, visual inspection),
- verification of connecting rods (measuring twist, wear, checking bolts),
- inspection of the injection pump on the test bench,
- analysis of the turbocharger condition.

Reconditioning and repair

Connecting rod-piston system

The components of the connecting rod-piston system—sleeves, rings, bearings—were replaced with new ones in accordance with the manufacturer's specifications. The connecting rods underwent full metrological control and re-fitting.

Cylinder head

The cylinder head was fully reconditioned—planing, replacement of guides, installation of new valves, machining of seats, and leak testing in a water bath. The goal was to fully restore factory parameters and eliminate the risk of valve burning again.

Fuel system

The injection pump was placed on a specialized test bench, where it was adjusted. The injectors were also verified, and the tips were replaced. The entire assembly was based on the nominal values of the Liebherr D9406 TI-E engine.

Engine accessories

The turbocharger, starter, alternator, and all electromechanical components were inspected. Only fully functional accessories ensure trouble-free operation of the crane in challenging construction conditions.

Professional engine assembly

The assembly of the engine was carried out according to Liebherr service guidelines. Each stage of assembly—from seating the crankshaft, through fitting the piston system, to installing the cylinder head—was performed in compliance with rigorous standards, and the tightening moments of the bolts were controlled with a torque wrench.

Engine dynamometer test

After assembly, the unit was taken to the WIBAKO dynamometer. Our dynamometer allows testing large units used in off-highway machines, which is a unique opportunity in the country.

The testing phase included:

- preliminary start-up under a load of 20-30% for about 16 operating hours,
- monitoring temperatures, pressures, combustion parameters,
- full loads in several working cycles
- multiple tests of engine behavior under sudden load increases.

The ability to conduct such detailed tests allows us to deliver to the client an engine that is completely verified, ready for operation, and without the risk of hidden defects.

Engine installation in the machine

After the tests were completed, the engine was transported back to the crane. The installation involved inserting the unit into the compartment, connecting oil, fuel, intake, and cooling lines. All connections were sealed, and the systems were tested for leaks.

Our specialists, together with the machine operator, conducted a series of functional tests, including:

- initial starts,
- monitoring crane operation under load,
- observing operating parameters during the first hours of operation.

Summary

After the repair, the Liebherr LR 1400/1 crawler crane regained full functionality and readiness for work. The Liebherr D9406 TI-E unit achieves nominal parameters, and thanks to the reconditioning of the cylinder head and internal components, we can ensure long and trouble-free operation.

We recommend performing a review after 50 operating hours, including filter replacement, leak testing, and assessment of the overall engine condition. Our WIBAKO mobile service is fully prepared to carry out such a review directly at the client’s location.