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The New Holland T6.175 and Its Hydraulic System
The New Holland T6.175 is a mid-range agricultural tractor designed for versatility across fieldwork, transport, and loader operations. Manufactured by CNH Industrial, New Holland has roots dating back to 1895 and has become a global brand with strong market presence in Europe and North America. The T6.175 features a 6.7L NEF engine, electronic power management, and a sophisticated hydraulic system that integrates rear axle lubrication with hydraulic fluid circulation.
This shared reservoir design simplifies maintenance but increases the consequences of contamination. The system typically holds around 16–17 gallons of hydraulic/transaxle fluid, such as Mobilfluid 426, which meets CNH MAT 3540 specifications. This fluid supports clutch packs, planetary gears, and hydraulic actuators under high pressure and temperature.
Accidental Diesel Contamination
In cold climates, diesel is sometimes used as a flushing agent for hydraulic systems after component failures. However, introducing diesel into a live hydraulic/transaxle reservoir—especially in a machine with wet clutch packs and precision gear assemblies—can compromise lubrication, reduce film strength, and accelerate wear.
In this case, approximately 1–2 gallons of diesel were mistakenly added to the reservoir and the tractor was operated for several hours before the error was discovered. While diesel has some lubricating properties, it lacks the anti-wear additives and viscosity stability required for gear and clutch protection.
Immediate Action Plan
To mitigate damage and restore system integrity, the following steps are recommended:
Terminology Clarification
In Arctic or sub-Arctic regions, diluted hydraulic oil is sometimes used to improve cold-start flow. Ratios below 3:1 (oil to diesel) may be tolerated in hydraulic-only systems, but not in shared axle/hydraulic reservoirs. Diesel thins the fluid, reducing protection for gear teeth and clutch surfaces under load.
One operator in northern Norway reported a hydraulic guide hose rupture that led to topping off the reservoir with mislabeled diesel. The leak persisted near the filter housing, possibly due to pressure spikes or seal fatigue. While frustrating, the incident highlighted the importance of labeling containers and understanding fluid compatibility.
A Story from the Field
In Manitoba, a farmer used diesel to flush a hydraulic system after a loader valve failure. The practice was recommended by a local hydraulic shop. However, he mistakenly left the diesel in the system and operated the tractor for a full day. The result was a scorched clutch pack and $4,000 in repairs. Since then, he labels every barrel and uses a dedicated flushing cart with staged dilution.
Preventive Measures and Best Practices
Accidental diesel contamination in a New Holland T6.175’s hydraulic/transaxle reservoir is serious but not necessarily catastrophic. With prompt drainage, inspection, and fluid replacement, long-term damage can often be avoided. The incident underscores the importance of fluid management, especially in machines with integrated systems and sensitive clutch assemblies.
The New Holland T6.175 is a mid-range agricultural tractor designed for versatility across fieldwork, transport, and loader operations. Manufactured by CNH Industrial, New Holland has roots dating back to 1895 and has become a global brand with strong market presence in Europe and North America. The T6.175 features a 6.7L NEF engine, electronic power management, and a sophisticated hydraulic system that integrates rear axle lubrication with hydraulic fluid circulation.
This shared reservoir design simplifies maintenance but increases the consequences of contamination. The system typically holds around 16–17 gallons of hydraulic/transaxle fluid, such as Mobilfluid 426, which meets CNH MAT 3540 specifications. This fluid supports clutch packs, planetary gears, and hydraulic actuators under high pressure and temperature.
Accidental Diesel Contamination
In cold climates, diesel is sometimes used as a flushing agent for hydraulic systems after component failures. However, introducing diesel into a live hydraulic/transaxle reservoir—especially in a machine with wet clutch packs and precision gear assemblies—can compromise lubrication, reduce film strength, and accelerate wear.
In this case, approximately 1–2 gallons of diesel were mistakenly added to the reservoir and the tractor was operated for several hours before the error was discovered. While diesel has some lubricating properties, it lacks the anti-wear additives and viscosity stability required for gear and clutch protection.
Immediate Action Plan
To mitigate damage and restore system integrity, the following steps are recommended:
- Drain the entire reservoir including rear axle and hydraulic fluid.
- Inspect suction screens for debris, especially clutch material or metal shavings.
- Replace all filters, including hydraulic and transmission filters.
- Perform a filter dissection (“filter chop”) to check for internal wear indicators.
- Refill with fresh OEM-spec fluid, ideally Mobilfluid 426 or equivalent.
- Monitor clutch engagement and hydraulic responsiveness during initial operation.
Terminology Clarification
- Wet Clutch Pack: A set of friction discs immersed in oil, used for gear shifting or PTO engagement.
- Suction Screen: A mesh filter located before the hydraulic pump to catch large debris.
- Filter Chop: A diagnostic procedure where a used filter is cut open to inspect trapped particles.
- MAT 3540: CNH’s specification for hydraulic/transaxle fluid performance.
In Arctic or sub-Arctic regions, diluted hydraulic oil is sometimes used to improve cold-start flow. Ratios below 3:1 (oil to diesel) may be tolerated in hydraulic-only systems, but not in shared axle/hydraulic reservoirs. Diesel thins the fluid, reducing protection for gear teeth and clutch surfaces under load.
One operator in northern Norway reported a hydraulic guide hose rupture that led to topping off the reservoir with mislabeled diesel. The leak persisted near the filter housing, possibly due to pressure spikes or seal fatigue. While frustrating, the incident highlighted the importance of labeling containers and understanding fluid compatibility.
A Story from the Field
In Manitoba, a farmer used diesel to flush a hydraulic system after a loader valve failure. The practice was recommended by a local hydraulic shop. However, he mistakenly left the diesel in the system and operated the tractor for a full day. The result was a scorched clutch pack and $4,000 in repairs. Since then, he labels every barrel and uses a dedicated flushing cart with staged dilution.
Preventive Measures and Best Practices
- Label all fluid containers clearly and store them separately.
- Use dedicated flushing carts with staged dilution protocols.
- Avoid diesel in systems with shared lubrication circuits.
- Perform fluid analysis after any contamination event.
- Keep spare filters and suction screens on hand for emergencies.
Accidental diesel contamination in a New Holland T6.175’s hydraulic/transaxle reservoir is serious but not necessarily catastrophic. With prompt drainage, inspection, and fluid replacement, long-term damage can often be avoided. The incident underscores the importance of fluid management, especially in machines with integrated systems and sensitive clutch assemblies.
