Engine overhaul Liebherr D9406 TI in Liebherr LTM 1070/1 telescopic mobile crane

Introduction

A Liebherr LTM 1070/1 telescopic mobile crane equipped with a Liebherr D9406 TI diesel engine arrived at our service. This model of the machine is distinguished by its high mobility and the ability to work in difficult construction conditions, which is why the reliability of the power unit is crucial. The crane is manufactured by the renowned company Liebherr, while the D9406 TI engine is a durable 6-cylinder unit designed specifically for heavy-duty work. The repair was necessary due to damage to the crankshaft, which manifested as uneven operation, vibrations, and unusual noises.

The preliminary diagnostics included measuring the crankshaft runout and analyzing vibrations. To confirm the defect, we performed non-destructive testing using penetrants and ultrasound, which unequivocally revealed serious damage to the crankshaft. In this situation, we decided to carry out a complete engine overhaul.

Engine disassembly

The disassembly of the Liebherr D9406 TI engine was carried out in the vicinity of Katowice, where the crane was performing construction work. Our mobile service arrived on site and, using a crane provided by the client, we disassembled the unit. The process included disconnecting the cooling system, intake and exhaust pipes, and the electrical installation. All components were properly secured for transport, and the engine itself was transported to our headquarters in Kojszówka for further verification and repair.

Verification of components

In the workshop, we conducted a full verification of the engine. The damage to the crankshaft was confirmed during detailed measurements of runout and visual inspection. In addition, we checked the connecting rods, pistons, and cylinder liners, which showed signs of wear. The cylinder head underwent a pressure test in a water bath using compressed air – no cracks were found. The turbocharger had excessive play, and the fuel injection pump required regeneration at a specialized facility.

Regeneration and repair

Connecting rod-piston system

The crankshaft was regenerated through grinding, and the bearings were replaced with new ones. We also regenerated the connecting rods, replacing the bolts and checking their straightness. The pistons and piston rings were replaced with new ones, and the cylinder liners were replaced and properly fitted.

Cylinder head

The cylinder head received new valves and valve guides, and the surface was planed. This restored its full tightness and durability.

Fuel system

The fuel injection pump was regenerated at an authorized facility. The injectors were tested on a test bench and then properly calibrated. The supply pump was also modernized.

Accessories

The turbocharger was repaired and balanced, and the starter and alternator were regenerated. All electro-mechanical components were thoroughly checked and prepared for reassembly.

Engine assembly

The assembly of the engine in the Liebherr LTM 1070/1 crane was carried out according to the manufacturer's procedures. We ensured the correct seating of the unit in the frame, proper tightening of the mounting brackets and the coupling. The intake and exhaust piping, as well as the fuel and cooling hoses, were replaced. The connections were sealed and pressure tested. Together with the crane operator, we conducted the first start-up and a series of tests, which confirmed the correct operation of the engine. The entire process was concluded with the preparation of a handover protocol.

Engine dynamometer test

WIBAKO, as one of the few companies in Poland, has its own engine dynamometer, which allows for a comprehensive check of the unit before installation in the machine. The Liebherr D9406 TI engine was started on the test stand and subjected to a 16-hour test under light load conditions, at approximately 25% of the nominal power. We then gradually increased the load to maximum values, repeatedly testing the stability of operation, oil pressure, coolant temperature, and exhaust parameters.

The dynamometer allowed for a detailed performance analysis, ensuring that the engine after regeneration operates fully in accordance with the manufacturer's specifications. As a result, the client received a unit 100% ready for further operation. Having a dynamometer in our company is a significant asset that minimizes the risk of failure after installation and builds trust in the quality of our services.

Engine maintenance after overhaul

After the engine rebuild, we always recommend the first filter change and inspection after 50 operating hours. Our mobile service visits the client and checks the condition of the accessories, the tightness of the connections, and the operating parameters. Subsequent inspections should be performed every 250 operating hours, but no less frequently than every 3 months.

Liebherr D9406 TI engines in other machines

The Liebherr D9406 TI power unit is used not only in LTM series self-propelled cranes but also in selected models of Liebherr wheeled loaders and excavators. Due to its durability and good operational parameters, it is widely used in machines requiring high power and reliability.

Summary

The comprehensive overhaul of the Liebherr D9406 TI engine in the Liebherr LTM 1070/1 telescopic mobile crane included diagnostics, disassembly, verification, repair of the connecting rod-piston system, regeneration of the cylinder head, fuel system, and accessories, followed by dynamometer tests and reassembly. As a result, the client received a machine ready for further intensive work. Regular service and inspection after 50 operating hours will ensure long and trouble-free operation.

Check also

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