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#1.Where to start?
The first step is to contact Łukasz, our coordinator for internal combustion engine repairs. You can call +48 33 870 42 15 or use the contact form available on our website.
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#2.How to deliver a combustion engine for repair?
You have several convenient options to choose from:
- Personal delivery to our workshop.
- Sending the engine by courier.
- We can also arrange for a courier to ship the engine on a pallet from a specified location, and after the repair service is completed, the courier will deliver it back.
- If you lack the appropriate facilities for disassembly or assembly, our mobile service can come to you and perform these services on-site. -
#3.How does the engine repair process proceed?
Our engine overhaul process is thorough and transparent:
- Detailed verification: the engine is disassembled down to the "last screw" and subjected to a detailed verification.
- Cost estimate and schedule: we prepare a comprehensive cost estimate and determine the expected repair time.
- Major overhaul: upon your acceptance of the terms, we proceed with a comprehensive repair, which is always a major overhaul, not just a replacement of individual components.
- Testing and painting: The overhaul is completed when the engine successfully passes tests at the engine dynamometer station. The final stage is professional engine painting. -
#4.What will you find in our offer?
We always strive to present you with the most beneficial solutions, therefore depending on the availability of spare parts you will receive:
- An estimate for repair with original parts.
- An estimate for repair with high-quality spare parts.
- As an alternative, we can propose purchasing the same refurbished engine from our warehouse, which often significantly shortens the completion time. -
#5.How long does it take to repair a combustion engine?
- The verification of your engine will take us 1-3 days from the moment of delivery.
- You will receive an estimate for typical repairs within the next business day after the verification is completed.
- The repair itself usually takes about 3-5 weeks. -
#6.How do we test combustion engines?
Every refurbished engine undergoes rigorous testing on our engine dynamometer. The unit is loaded in a way that simulates operation in a construction machine. During the tests, we check key parameters such as:
- Power and torque performance.
- Coolant and oil temperature.
- Oil pressure depending on its temperature.
- Behavior and performance changes in relation to load.
The entire test lasts on average from 12 to 24 hours, depending on the specifics of the engine. -
#7.How can I be sure that the engine will work after the repair?
We care about the highest quality:
- We perform repairs exclusively on high-quality parts, and assembly work is always in accordance with the specification of a given engine.
- After the repair, the engine is thoroughly tested. The test result is always available in the form of a readable chart.
- You will receive a 12-month warranty for each repair. In case of questions regarding assembly or operation, we encourage you to use the expert knowledge of our sales advisors through a phone call. -
#8.Can I cancel the repair after receiving the estimate?
Yes, you can cancel the repair without any costs after receiving the estimate and before accepting it.
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#9.How much does it cost to repair my engine?
The cost of repair depends on several factors: the engine model, the degree of its wear and tear, and the scale of damage. Very often we can only provide an approximate price range, based on our history of similar repairs.
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#10.Do you overhaul industrial and special-machinery engines?
Yes, we overhaul combustion engines for construction, industrial and special machinery. Write to us via the contact form.
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#11.Is an exchange engine possible?
If we have the same overhauled engine in stock, we can offer it as an alternative, which often significantly shortens the lead time. Write to us via the contact form.
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#12.Do you remove the engine at the customer's site?
Yes, our mobile service can come to you and perform the engine removal and installation on-site. Write to us via the contact form.
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#13.What does the warranty after overhaul look like?
Every engine overhaul comes with a 12-month warranty, and the engine is tested on the dynamometer after the work. Write to us via the contact form.
Liebherr D934 L A6 - service and repair
Complete repair, rebuild and test-bench runs for Liebherr D934 L A6 engines. Door-to-door collection across Poland. Warranty of up to 12 months. The engine is fitted in LIEBHERR machines including wheeled and crawler excavators (A904, A914, R914), wheel loaders (L524, L538) and material handlers (LH22, LH24). LIEBHERR service at WIBAKO.
- Original parts
- Dynamometer test report after repair
- Short lead times
- Technical support and replacement selection
Contact form
Liebherr D934 engine – what to know before a repair
The Liebherr D934 is a four-cylinder, inline diesel engine with a displacement of about 7 litres. It is turbocharged and intercooled. It powers Liebherr wheeled and crawler excavators, loaders, dozers and material handlers. In these machines it runs for thousands of operating hours under heavy, fluctuating loads, in dust, often with long periods of idling. This duty cycle determines what wears out and when.
At the WIBAKO workshop we diagnose, repair and overhaul D934 engines in all versions found in the field. Minor faults (ancillaries, injection, sensors, leaks) are fixed with the engine in the machine, including on the customer's site. Full overhauls are carried out with the engine removed, at our workshop in Kojszówka.
D934 S A6, D934 L A6 and D934 A7 variants
The A6 or A7 part of the designation indicates the engine generation, which is linked to exhaust emission standards. A7 is the newer generation. Within A6 there are S and L versions, which differ in ancillaries and settings for specific machines, among other things. Before ordering parts, always provide the full designation and serial number from the engine data plate. Part numbers for pistons, gaskets, injectors and ancillaries change within a single engine type.
D934 S A6
An older version of the A6 generation, found in high-hour machines. The mechanical components respond well to rebuilding. With these engines, however, we often come across signs of previous repairs, so before quoting we carefully measure the block, cylinder head and crankshaft.
D934 L A6
This version is fitted in, among others:
- A904, A914 and R914 excavators,
- L524 and L538 wheel loaders,
- LH22 and LH24 material handlers.
It most often comes to us with blow-by, loss of power or after overheating.
D934 A7
The newer generation with more advanced engine management, more sensors and, depending on the machine, an exhaust aftertreatment system with a diesel particulate filter. It is used in the PR 736 dozer, the LR 636 crawler loader and the A 924 excavator, among others. Details of this version are covered on the page Liebherr D934 A7 engine service and repair.
Typical symptoms of engine damage
- Loss of power – the engine does not reach rated speed and the machine loses pulling power under load.
- Excessive smoke – exhaust smoke points to a problem with injection, the turbocharger or wear in the piston and crank assembly:
- black – usually injection or air intake,
- blue – oil burning,
- white – often coolant in the cylinder.
- Unusual noises – knocking, rattling or metallic sounds may indicate worn bearings, pistons or valves.
- Vibration and overheating – rough running and rapidly rising temperature are signs of damage to the cooling system or mechanical components.
Most common D934 engine failures
- Liners, pistons and rings – wear causes blow-by into the crankcase, oil consumption and blue smoke. Dust entering through a leaking intake speeds this up several times over.
- Bearings and crankshaft journals – damaged by a drop in oil pressure, fuel dilution of the oil or overly long change intervals.
- Cylinder head and head gasket – after overheating, cracks between valve seats, burnt seats and gasket leaks can occur.
- Turbocharger – shaft play, oil leaking into the intake, loss of boost pressure.
- Injectors – incorrect delivery and leaks, showing up as rough running, black smoke and hard starting.
- Cooling system and oil cooler – oil in the coolant, overheating, deposits in the passages.
- Emissions equipment (A7) – clogged diesel particulate filter, faulty sensors, limp mode with reduced power.
A failure rarely has a single cause. A typical chain of events looks like this: a dirty radiator leads to overheating, overheating cracks the cylinder head, and coolant in the oil destroys the bearings. Simply replacing the damaged part without eliminating the cause means the failure will come back. That is why every repair starts with finding out what triggered it.
What we do as part of the service
Diagnostics & tests
Pressure measurement, flow tests, test bench verification.
Overhaul
Replacement of rotating elements, seals, surface finishing.
Calibration
Precise adjustment of valves and controls.
Upgrades
Selection of replacements and adaptations.
Door-to-door
Pick-up and delivery throughout Poland.
Warranty & report
Test protocol and warranty up to 12 months.
Repair process and dyno test
- Interview and diagnostics – reading fault codes from the ECU, measuring compression, blow-by and oil pressure, assessing smoke and leaks.
- Disassembly and cleaning – stripping the engine and cleaning components for measurement.
- Measurement and inspection – liner ovality and taper, crankshaft journal diameters, flatness of the head and block, cylinder head pressure test, condition of valve seats and guides.
- Quote and scope agreement – the customer receives a list of damage and parts to be replaced or reconditioned.
- Rebuild and assembly – crankshaft regrinding, cylinder head machining, new pistons, rings, bearings and seals, reconditioning or replacement of injectors and turbocharger.
- Dyno test – a run under load with checks of power, oil pressure, temperatures, tightness and smoke.
- Installation in the machine and handover – start-up, parameter check and running-in recommendations.
The dyno test detects assembly errors and leaks before the engine goes back into the machine. Removing it again for a correction costs many times more than fixing it on the test bench.
What the repair process looks like
Contact
By phone or via the form.
Collection
We arrange a courier; on-site disassembly possible.
Diagnostics
Disassembly, measurements, cost estimate for approval.
Repair & test
Assembly, calibration, test bench verification.
Fault codes and computer diagnostics
D934 engines store faults in the ECU. Reading them with a diagnostic tool is the first step, especially on the A7 version with its extensive emissions equipment. The meaning of individual codes is explained in the article Liebherr D934 L A7 and D936 L A7 fault codes – complete diagnostics.
A fault code is a clue, not a ready-made diagnosis. A boost pressure fault may mean a faulty sensor, a chafed wire, a leaking intake or a worn turbocharger. Before replacing any parts, we always check the wiring and take comparative measurements.
Overhaul, rebuild or engine replacement
A D934 overhaul makes sense when the block and cylinder head are not cracked and the crankshaft can be reground to undersize. After such an overhaul the engine gets new liners, pistons, rings, bearings and seals, and runs like a zero-hour unit.
Replacement may be the better option when:
- the block is cracked,
- the bearing bores were destroyed in a seizure,
- machine downtime costs more than the price difference.
The WIBAKO shop offers, among others, a Liebherr D934 L A6 engine and a Liebherr D934 A7 engine. It is best to confirm the availability and condition of a specific unit by phone.
How much does a Liebherr D934 engine repair cost
The cost of an overhaul depends on the extent of damage and the number of parts to be replaced. That is why we prepare a binding quote after diagnostics and measurements. Labour is charged at the following rates:
- mechanic's hourly rate: PLN 230 net (per mechanic),
- hourly rate for fitting parts purchased from WIBAKO: PLN 190 net,
- scheduled service: PLN 1,400 net (excluding travel and materials),
- travel: PLN 3 net per km, charged both ways.
For an initial assessment, please have ready:
- the full engine designation and serial number,
- the machine model,
- the number of operating hours,
- a description of the symptoms and any fault codes read.
Case studies: D934 in PR 736, LR 636 and A 924
We have overhauled D934 A7 engines in machines from various groups, including:
- crawler dozer – Liebherr D934 A7 engine overhaul in a PR 736 dozer,
- crawler loader – D934 A7 engine overhaul in an LR 636 Litronic loader,
- excavator – Liebherr A 924.
The write-ups show the complete workflow: from damage inspection, through assembly, to post-overhaul testing.
Liebherr D934 L A6 repair - quote in 15 min
We restore Liebherr D934 L A6 engines to factory specifications. We service LIEBHERR machines: A904, A914, R914 excavators, L524, L538 loaders and LH22, LH24 material handlers. Call us or send the form - we will collect components door-to-door, carry out test-bench runs and provide a written warranty of up to 12 months. WIBAKO - a service that delivers results.
Frequently asked questions
What is the difference between the Liebherr D934 A6 and D934 A7 engines?
The A7 is the newer generation of the D934, designed for stricter exhaust emission standards. It has more sensors, more advanced engine management and, depending on the machine, an exhaust aftertreatment system with a diesel particulate filter. For this reason, ancillary and injection parts are not interchangeable between generations.
Is a Liebherr D934 engine overhaul worth it?
Usually yes, provided the block and cylinder head are not cracked and the crankshaft can be reground. If the block is damaged or downtime is critical, replacement with a used or rebuilt engine is considered. We make the decision after disassembly and measurements.
How much does a Liebherr D934 engine repair cost?
The cost depends on the extent of damage and the parts needed, so we prepare a quote after diagnostics and measurements. The mechanic's hourly rate is PLN 230 net, and PLN 190 net when fitting parts purchased from WIBAKO. Travel costs PLN 3 net per km, charged both ways.
Is the D934 engine tested on a dyno after the overhaul?
Yes, before installation in the machine the engine undergoes a test under load. We check power, oil pressure, temperatures, tightness and smoke.
Which machines use the Liebherr D934 engine?
The D934 L A6 is found in A904, A914, R914 excavators, L524, L538 loaders and LH22, LH24 material handlers, among others. The A7 version is used in the PR 736 dozer, the LR 636 crawler loader and the A 924 excavator, among others.
What should I prepare before requesting a D934 repair?
The full designation and serial number from the engine data plate, the machine model and the number of operating hours. A description of the symptoms and any fault codes read will also help. This makes it easier to assess the scope of repair and select the right parts.
