At Maude Diesel Service, our team recently completed a major engine replacement and conversion project after diagnosing internal engine failure during a routine service on a Kenworth K401.
What began as a standard service quickly turned into a significant repair, after our technicians discovered serious internal engine damage. The project involved removing the failed Cummins engine and converting the truck to a CAT engine, chosen specifically to match the customer’s existing fleet of trucks and ensure consistency in maintenance, parts, and performance.
This case highlights the importance of routine truck servicing, early fault detection, and expert diesel diagnostics for fleet operators.
Routine Truck Service Leads to Major Discovery
The Kenworth K401 was booked into our Geelong workshop for a standard engine service and inspection. As part of our routine service procedure, our technicians performed a full check of the vehicle including:
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Engine oil and filter replacement
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Inspection of lubrication systems
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Cooling system inspection
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Visual engine and driveline checks
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General safety and mechanical inspection
During the oil drain process, our technicians identified metallic particles present in the engine oil, which is often a clear warning sign of internal engine wear or failure.
To investigate further, our mechanics removed the engine sump for a more detailed inspection.
Severe Metal Contamination Found in Engine Sump
Once the sump was removed, the cause of concern became obvious. The sump contained significant metal contamination, indicating serious internal engine damage.
Metal fragments inside engine oil typically occur when critical internal components begin to fail. These fragments circulate through the lubrication system and can rapidly cause further damage to engine parts such as:
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Crankshaft bearings
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Pistons and liners
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Oil pump components
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Camshaft and valve train assemblies
At this stage it became clear that the engine had suffered major internal failure, and further operation could have resulted in a complete engine seizure.
Discussing Repair Options with the Customer
At Maude Diesel Service, we believe in providing clear and honest advice to our customers.
After confirming the damage, we contacted the truck owner to discuss the findings and review the available repair options. These included:
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Full engine rebuild
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Partial engine repair
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Complete engine replacement
Due to the level of metal contamination throughout the engine, the most reliable long-term solution was determined to be a complete engine replacement.
This option would ensure the truck returned to service with maximum reliability and minimal risk of further internal damage.
Cummins to CAT Engine Conversion for Fleet Compatibility
After diagnosing the issue, several repair options were considered with the customer, including:
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Engine rebuild
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Partial engine repair
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Complete engine replacement
The customer and our team decided on a full engine replacement using a CAT engine, chosen to match the rest of their large fleet.
Fleet consistency provides several advantages:
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Easier maintenance and servicing
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Simplified parts supply and inventory
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Standardised performance across vehicles
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Reduced long-term operating costs
This type of engine conversion requires extensive mechanical expertise, including ensuring compatibility with the truck’s systems and aligning all supporting components.
Engine Removal and Replacement Process
Our technicians carried out the complete Cummins-to-CAT engine conversion process.
Removal of Failed Cummins Engine
The damaged engine was carefully removed, including disconnection from:
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Cooling system
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Fuel system
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Exhaust system
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Electrical components
Inspection of Supporting Systems
All supporting systems were checked to ensure compatibility with the replacement CAT engine, including:
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Cooling system components
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Engine mounts and driveline connections
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Fuel delivery systems
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Lubrication lines and filters
Installation of CAT Engine
The replacement CAT engine was installed and aligned correctly, ensuring all components were properly connected and secured.
Special attention was given to cleaning systems affected by metal contamination, including replacing filters, flushing lubrication lines, and topping up fluids.
Testing and Recommissioning
After installation, the truck underwent a full recommissioning process including:
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Engine start-up and monitoring
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Oil pressure and temperature checks
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Diagnostic inspections
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Leak checks
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Road testing under operating conditions
Once all systems were confirmed operating correctly, the Kenworth truck was returned to the customer ready to resume service, now aligned with their fleet’s CAT engine setup.
Professional Engine Removal and Replacement
Once approval was received, our technicians began the process of removing the failed engine from the Kenworth truck.
Engine Removal
The damaged engine was carefully disconnected and removed, including separation from the cooling system, fuel system, exhaust system and electrical components.
System Inspection
Before installing the replacement engine, our team inspected all supporting systems including:
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Cooling system components
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Fuel delivery systems
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Engine mounts and driveline connections
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Lubrication system lines and filters
This ensures there are no underlying issues that could affect the new engine.
Replacement Engine Installation
The replacement engine was installed and aligned correctly within the chassis, with all components carefully reconnected and secured.
Cleaning and Fluid Replacement
Because metal contamination was present, additional care was taken to ensure:
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The lubrication system was cleaned
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New oil filters were installed
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Fresh fluids were added
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Systems were flushed where required
Testing, Diagnostics and Road Testing
After installation, the truck underwent a complete recommissioning process to confirm everything was operating correctly.
Testing procedures included:
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Initial engine start-up and monitoring
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Oil pressure and engine temperature checks
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Diagnostic inspections
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Leak checks and system verification
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Road testing under operating conditions
Once all systems were confirmed to be performing correctly, the Kenworth truck was returned to the customer ready to get back on the road.
Trusted Diesel Mechanics in Geelong
Projects like this demonstrate the importance of working with experienced heavy diesel mechanics who understand truck engines and diagnostics.
At Maude Diesel Service, our team provides professional diesel repairs and servicing for truck owners, transport operators and fleet managers across Geelong and surrounding regions.
We specialise in:
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Heavy diesel truck servicing
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Truck engine diagnostics
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Engine rebuilds and replacements
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Fleet servicing and maintenance
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Roadworthy inspections
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Truck repairs and breakdown diagnosis
We regularly work on leading truck brands including Kenworth, Volvo, Freightliner, Isuzu and other commercial vehicles.
Book a Truck Service or Roadworthy Inspection
If your truck requires servicing, repairs or a Roadworthy Certificate, our experienced team can help keep your vehicle safe, compliant and operating reliably.
Contact Maude Diesel Service today to book your truck in.
📞 Phone: 0352782900 or 0404 147 629
📧 Email: ryan@maudediesel.com.au
📍 Location: North Geelong, Victoria
We provide truck servicing, diesel repairs, engine replacements, roadworthy inspections and fleet maintenance across Geelong and surrounding areas.
