Renovation of the Liebherr D9406 TI Engine in the LTM 1090/1 Crane

Overhaul of Liebherr D9406 TI Engine in a Liebherr LTM 1090/1 Telescopic Mobile Crane

Introduction

A Liebherr LTM 1090/1 telescopic mobile crane equipped with a Liebherr D9406 TI diesel engine arrived at our service center. This machine belongs to the class of all-terrain cranes with a lifting capacity of up to 90 tons, making it a versatile solution for construction and assembly work. Thanks to its mobility and compact design, this model is frequently used in urban projects and infrastructure developments.

The manufacturer of both the machine and the power unit is Liebherr—a renowned producer of construction equipment and diesel engines designed for heavy-duty conditions. The Liebherr D9406 TI engine is a 6-cylinder unit featuring high power and durability, engineered for long-term operation under high loads.

The reason for sending the machine to our service was a loss of power and increased oil consumption. The operator also reported excessive smoke during operation under load. Initial diagnostics included measuring compression pressure and exhaust gas analysis. Additionally, we performed a cylinder leak test and an endoscopic inspection, which indicated wear on the crank-piston assembly components.

Engine Disassembly

The engine disassembly was carried out directly at the client's site near Katowice. Our mobile service performed all work using a crane provided by the client. The process involved disconnecting all systems—fuel, cooling, air intake, and electrical installations.

Particular attention was paid to properly securing hoses and peripheral components to avoid damage during transport. After unscrewing the mounts, the engine was safely removed from the machine frame and prepared for transport to our headquarters in Kojszówka.

Component Verification

Upon delivery of the engine to our workshop, we began a detailed verification process. The engine was completely disassembled, and all components were cleaned and subjected to a technical assessment.

The verification confirmed our earlier suspicions: significant wear was found on the cylinder liners and pistons. Additionally, wear on the piston rings was noted, which was the direct cause of the drop in compression and increased oil consumption.

An inspection of the crankshaft, connecting rods, and camshaft was also conducted. The engine head underwent a leak test in a water bath, and the condition of the valves and guides was checked. The injection system was sent to a test bench for thorough performance analysis.

Regeneration and Repair

The repair process involved a comprehensive regeneration of all key engine elements. Regarding the crank-piston system, the crankshaft was ground and new bearings were applied. The cylinder liners were replaced, as were the pistons and rings.

The engine head underwent a resurfacing process and the replacement of valve guides and valves. The fuel system was regenerated—the injectors and injection pump were tested and calibrated.

Engine accessories, including the turbocharger, alternator, and starter, were subjected to detailed inspection. For the turbocharger, longitudinal and transverse play were checked, followed by its regeneration.

The entire unit was reassembled according to manufacturer standards, maintaining appropriate tightening torques and assembly procedures.

Engine Installation

Installing the engine in the Liebherr LTM 1090/1 crane was a process requiring precision and experience. After transporting the power unit back to the job site, our service team proceeded with the installation in the engine compartment.

The assembly process included the precise seating of the engine on its mounting brackets, followed by the reconnection of all fuel, cooling, air intake, and electrical systems. Selected hoses and rubber elements were also replaced to ensure the full tightness of the systems.

Following the installation, detailed leak tests and the first engine start-up were performed. Our technicians conducted tests in the presence of the machine operator, monitoring operating parameters and checking for any potential leaks. Following positive results, an acceptance protocol was drawn up.

Engine Dynamometer Test

One of the key stages of the project was testing the engine on our engine dynamometer (dyno). This advanced station allows for an accurate check of the unit's operating parameters before it is installed in the machine, providing a massive advantage over standard service methods.

The Liebherr D9406 TI engine was subjected to several hours of testing under controlled load conditions. Initially, it ran for several hours at a load of approximately 20-30% of nominal power, allowing the components to properly break in after the overhaul. The load was then gradually increased until full power was reached.

During the tests, all key parameters were monitored—oil pressure, operating temperature, combustion parameters, and RPM stability. This allowed us to detect any irregularities at a very early stage.

The dynamometer also allows for the simulation of real working conditions, which is extremely important for machines like cranes. As a result, the client receives a fully tested engine, ready for work without the risk of unplanned downtime.

Post-Overhaul Maintenance

After completing the installation and starting the machine, we provided the client with recommendations for further operation. We recommend the first service inspection after 50 operating hours. This includes replacing filters and inspecting all connections.

Subsequent inspections should be performed every 250 operating hours or at least every 3 months. Our mobile service provides full support in terms of maintenance and diagnostics.

Application of the Liebherr D9406 TI Engine

The Liebherr D9406 TI engine is used in many construction machines, particularly in mobile cranes and other machinery requiring high power and reliability. It is a unit valued for its durability and resistance to intensive use.

Summary

The completed overhaul of the Liebherr D9406 TI engine in the Liebherr LTM 1090/1 crane allowed for the restoration of the machine's full efficiency and a significant extension of its service life. Thanks to a comprehensive approach and the use of an engine dynamometer, the client received a proven engine ready for operation.

WIBAKO specializes in diesel engine repairs and construction machinery service. We offer both stationary repairs and mobile support throughout the country.

Internal Links

Liebherr Engine Service
Diesel Engine Overhauls
Construction Machinery Service