Overhaul of the D926 TI-E Engine in the Liebherr LTM 1050/1 Mobile Crane

Overhaul of the D926 TI-E Engine (230 kW) in a Liebherr LTM 1050/1 Mobile Crane

Comprehensive Service of the Liebherr LTM 1050/1 Mobile Crane

Our service center received a Liebherr LTM 1050/1 mobile crane equipped with a Liebherr D926 TI-E engine with 230 kW of power. The machine was operating on infrastructure investment projects near Katowice in the Silesian Voivodeship. The operator reported a gradual loss of power, increased engine oil consumption, and heavy smoke during operation under load. Additionally, there were issues with maintaining stable RPM during cold starts.

The Liebherr LTM 1050/1 is a popular all-terrain mobile crane used in the construction, energy, and industrial sectors. The machine's design allows for efficient movement both on public roads and on construction sites with difficult terrain conditions. Due to high operating loads and long working hours, the power unit requires regular servicing and monitoring of performance parameters.

The D926 TI-E engine used in Liebherr cranes is a six-cylinder diesel unit designed for heavy-duty applications. Engines of this series are valued for their durability; however, high mileage or improper maintenance leads to wear of the crank-piston system and auxiliary components. In this case, diagnostics revealed excessive wear on the cylinders and pistons, causing a loss of compression.

Our mobile diesel engine service performed a full diagnostic of the machine directly at the customer's site. After confirming the necessity of a general overhaul, the engine was dismantled using a crane provided by the machine owner and transported to our headquarters in Kojszówka, where we performed a comprehensive rebuild of the power unit along with tests on an engine dynamometer.

Initial Diagnostics of the D926 TI-E Engine

We began the diagnostic process by checking the engine's operating parameters directly in the Liebherr LTM 1050/1 crane. The operator reported a clear drop in performance during boom operation and increased oil consumption. During the initial inspection, we noticed heavy exhaust smoke under load and uneven engine operation at idle.

In the first stage, we measured the oil pressure and checked the cooling system parameters. This was followed by a compression pressure measurement on all cylinders. The results showed significant differences between individual cylinders, indicating wear of the crank-piston system components. Additionally, we performed an endoscopic inspection of the cylinder interiors, which revealed signs of wear on the liner surfaces and excessive carbon buildup.

To confirm the damage, a cylinder leak test and exhaust gas analysis were performed. The tests confirmed blow-by into the crankcase and improper fuel mixture combustion. After completing the diagnostics, the decision was made to perform a comprehensive overhaul of the Liebherr D926 TI-E engine.

Engine Removal from the Liebherr LTM 1050/1 Crane

The engine removal was carried out by our mobile service near Katowice. Due to the mobile crane's design and limited workspace, the entire process required proper preparation of the workstation and protection of the hydraulic and electrical systems.

Before starting the removal, the batteries were disconnected and the machine's electrical system was secured. Subsequently, operating fluids were drained, and auxiliary components that hindered the removal of the power unit were dismantled. Particular attention was paid to securing the hydraulic lines, cooling system, and intake ducts.

The engine was disconnected from the transmission and the chassis frame mounts. The entire operation was performed using a crane provided by the customer. After removing the power unit, an additional inspection of the engine compartment, mounts, and auxiliary installations was conducted. All cables and connections were labeled to ensure full compliance with service documentation during reinstallation.

Once prepared for transport, the engine was taken to our service base in Kojszówka, where a detailed verification of all components began.

Verification of the Liebherr D926 TI-E Engine

After the power unit was delivered to the workshop, we began a full engine teardown. Even during the initial inspection, excessive wear of the cylinder liners and signs of blow-by on the pistons were confirmed. Small metal shavings were also found in the oil pan, indicating progressive wear of the moving parts.

The crankshaft verification included measuring the main and connecting rod journals, checking the oil passages, and inspecting for crankshaft runout. Despite signs of wear, the shaft was suitable for regeneration through grinding to the appropriate oversize.

The connecting rods were measured for twist and checked for overheating and micro-cracks. Verification showed the necessity of replacing some connecting rod bolts and piston pin bushings.

The engine head underwent a pressure test in a heated water bath. The inspection revealed leaks in the valve seats and wear of the valve guides. Additionally, the condition of the camshaft was checked; its lobes showed moderate operational wear.

A turbocharger verification was also performed by measuring the axial and radial play of the rotor. The injection system was sent for testing on a test bench, which confirmed the uneven operation of some injectors.

Regeneration and Repair of the D926 TI-E Engine

The engine rebuild process began with the regeneration of the block and the crank-piston system. The cylinders were machined, and the block was prepared for the installation of new liners. New pistons, piston rings, and a set of main and rod bearings were used.

The crankshaft underwent professional grinding, followed by a balance check and verification of oil passage patency. All components were thoroughly cleaned and prepared for assembly according to the manufacturer's documentation.

Head regeneration included resurfacing the contact area, replacing valve guides and valves, and machining the valve seats. After the work was completed, the head passed another pressure test.

The fuel system underwent comprehensive servicing. The injectors were tested on a bench, and damaged parts were replaced. The injection pump was sent for specialized regeneration at an external facility cooperating with our service center.

As part of the repair, the turbocharger was regenerated, and the alternator and starter were checked. Oil lines, seals, and cooling system components responsible for maintaining the correct operating temperature were replaced.

The engine assembly process was carried out according to Liebherr service procedures. Each component was installed using the correct tightening torques and assembly clearances. After assembly was completed, initial leak tests were performed, and the engine was prepared for dynamometer trials.

Engine Dynamometer Testing

One of the most important stages of the entire process was the engine dynamometer test. Our company belongs to a small group of diesel engine services capable of fully testing power units before they are installed in a machine. This ensures the customer receives a verified engine with operating parameters checked even before transport to the assembly site.

The Liebherr D926 TI-E engine was mounted on the dyno stand and connected to measuring systems monitoring temperature, oil pressure, boost pressure, combustion parameters, and load stability. The first stage of testing involved breaking in the unit for several hours at a partial load of approximately 20-30% of its nominal value.

During the trials, our mechanics monitored the engine's behavior at various RPM ranges. Leakage in all systems, temperature stability, and lubrication parameters were controlled. Oil filtration and the presence of any contaminants that could indicate improper component operation were regularly checked.

After the initial break-in stage, the engine was repeatedly subjected to full load. The dynamometer allowed for an accurate check of the power output and the unit's reaction to dynamic load changes characteristic of mobile crane operation. The tests confirmed the correct operation of the fuel system, turbocharger, and cooling system.

A major advantage of dyno testing is the ability to detect potential problems before the engine is mounted in the machine. In practice, this means reducing the risk of downtime and additional costs for the customer. Thanks to extensive measuring equipment, we can precisely analyze operating parameters and compare them with the manufacturer's nominal values.

After completing all trials, control filters were replaced, and the interior of the lubrication system was inspected again. The engine achieved correct operating parameters and was approved for installation in the Liebherr LTM 1050/1 crane.

Engine Installation in the Mobile Crane

We performed the power unit installation again at the customer's site near Katowice. Before installation, the engine compartment was prepared, and a thorough inspection of hydraulic lines, mounts, and cooling system components was carried out.

The engine was seated using a crane provided by the customer. During installation, special attention was paid to the correct alignment of the mounts and the connection of the engine to the crane's drive system. All fuel, oil, and intake lines were carefully checked for leaks.

Parts of the intake system lines and rubber components showing signs of aging were replaced. The condition of the radiators and the correct operation of the fans responsible for maintaining the engine's operating temperature were also checked.

After assembly, the first startup of the unit was performed in the presence of the machine operator. Our mechanics conducted a series of operational tests including working the crane under load, monitoring engine response to RPM changes, and checking all operating parameters.

During the trials, the tightness of connections, the correct operation of the fuel system, and the absence of oil and coolant leaks were verified. After a successful completion of the tests, an installation protocol was drawn up, and the machine was handed over for further operation.

Post-Overhaul Service Maintenance

Every engine overhauled by us is covered by a warranty and the possibility of further service support. For the Liebherr D926 TI-E engine, we recommended the first inspection after 50 operating hours. During such an inspection, our mechanics check the tightness of connections, filter condition, and the unit's operating parameters.

Subsequent inspections are performed every 250 operating hours or at least every three months. Regular maintenance allows for maintaining high durability of the power unit and reduces the risk of serious failures during mobile crane operation.

Machines Using the Liebherr D926 TI-E Engine

The Liebherr D926 TI-E engine is used in many off-highway machines and equipment utilized in the construction and industrial sectors. This unit is used, among others, in Liebherr mobile cranes, material handlers, and specialized off-road vehicles.

Due to its high design durability, engines of this series are popular in machines working under high loads for many hours a day. At the same time, they require regular servicing and professional diagnostics, especially at high operating mileages.

Summary of the Liebherr D926 TI-E Engine Overhaul

The comprehensive overhaul of the D926 TI-E engine in the Liebherr LTM 1050/1 mobile crane restored the machine's full functionality and eliminated problems related to loss of compression and excessive oil consumption. Thanks to full diagnostics, professional component regeneration, and engine dynamometer testing, the customer received a verified unit ready for further intensive operation.

Our construction machinery service performs comprehensive diesel engine repairs, mobile disassembly and assembly, and professional engine dynamometer tests. We serve mobile cranes, excavators, loaders, crushers, screeners, and other off-highway machines throughout Poland.

In the case of Liebherr engines, we perform both major overhauls and routine maintenance. Thanks to the experience of our mechanics and specialized technical facilities, we are able to effectively diagnose and repair even the most demanding damage.

Related services:
Liebherr engine service
Mobile crane repairs
Engine dynamometer tests
Construction machinery service