2010 — 2018
6.7L Cummins I6 (ISB 6.7)
Diesel
Perform a cold start and watch for blue or white smoke, then drive at highway speeds (80-100 km/h) to check for DPF regeneration warning messages or sluggish acceleration. | Note: NZ's short-trip driving cycles frequently clog the DPF and EGR valve on these imported heavy-duty rigs, leading to costly 'limp mode' events.
Test gear shifts under moderate to heavy acceleration. Feel for hesitation, flare shifts, or clunking when shifting between 3rd and 4th gears on the 68RFE automatic transmission. | Note: The standard 68RFE automatic transmission is a notorious weak point under heavy torque loads; check if an aftermarket valve body or heavy-duty cooler has been fitted.
Drive over uneven road surfaces at 70-90 km/h and check for excessive play in the steering wheel or any violent front-end vibrations (the 'death wobble'). | Note: The immense weight of the iron-block Cummins I6 causes rapid wear on track bars, ball joints, and steering linkages, which can trigger steering instability.
Listen for a high-pitched squeal or mechanical scraping under load, and monitor the factory exhaust brake operation during deceleration to ensure it engages smoothly. | Note: The electronic actuator on the Holset Variable Geometry Turbo (VGT) is highly prone to soot accumulation, sticking, and eventual complete failure.
Replace both the engine-mounted and chassis-mounted fuel filters (dual-stage setup) and perform an engine oil and filter service. Essential to protect the high-pressure common-rail injectors from NZ diesel fuel quality variations.
Flush and replace the automatic transmission fluid (ATF) and filters. Inspect the front and rear differential oils, transfer case fluid, and lubricate the hard-to-reach front driveshaft grease fitting.
Perform a valve lash adjustment on the 24-valve head. Inspect the EGR cooler and valve for carbon buildup, replace the Crankcase Ventilation (CCV) filter on top of the valve cover, and evaluate the steering dampener.
Replace dual fuel filters every 15,000 to 20,000 km to safeguard the expensive high-pressure fuel injection pump.
Service the Crankcase Ventilation (CCV) filter located on top of the valve cover every 100,000 km to prevent oil seal leaks.
Frequently grease the front driveshaft double-cardan joint using a needle-nose grease gun adapter during every oil change.
Monitor DEF (Diesel Exhaust Fluid) system heater lines for crystallization and failure, especially in colder South Island climates.
Adjust the intake and exhaust valve clearances (lash) every 150,000 km to maintain optimal engine breathing and fuel efficiency.
Estimated repair costs if issues arise
Standard factory rebuilds will fail again under heavy towing; a heavy-duty rebuilt unit with upgraded clutch packs and a billet torque converter is highly recommended in NZ.
Importing heavy diesel parts to NZ carries high freight costs. Expect premium pricing for OEM replacements, though aftermarket heavy-duty upgrades are available.
Replacing failed DPF filters or EGR coolers with factory-compliant parts is incredibly expensive. Legal compliance must be maintained for NZ Certificate of Fitness (CoF) standards.
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Disclaimer: This report is generated with the assistance of AI analysis based on verified automotive data. While we strive for 100% accuracy, enthusiasts should always conduct physical inspections and consult service records. View Full Disclaimer