08-25-2025, 11:15 PM
Bobcat’s Engine Transition and the Rise of Doosan Powerplants
Bobcat, originally founded in North Dakota in the 1950s, became synonymous with compact equipment—especially skid steer loaders. For decades, Bobcat relied heavily on Kubota diesel engines, known for their reliability, cold-start performance, and global parts availability. However, following Bobcat’s acquisition by Doosan Infracore in 2007, a gradual shift began toward integrating Doosan-built engines into Bobcat machines, particularly to meet Tier 4 emissions regulations.
Doosan, a South Korean industrial conglomerate with deep roots in heavy equipment and power systems, developed its own Tier 4-compliant diesel engines to meet EPA standards. These engines were introduced into Bobcat’s S-series and M-series skid steers, including models like the S650 and T770. While the move aimed to streamline manufacturing and reduce dependency on third-party suppliers, it also introduced new challenges—especially in cold climates.
Terminology Clarification
Operators in northern regions began reporting issues with Doosan-powered Bobcats during winter months. The most common symptoms included:
Another technician observed that injectors on these engines could cost upwards of $800 each, not including labor. A fueling system failure around 2,500 hours was suspected to be linked to inconsistent rail pressure and premature injector wear.
Comparisons to Kubota-Powered Bobcats
Many long-time Bobcat users compared the Doosan engines unfavorably to the Kubota diesels used in earlier models. Kubota engines, particularly the V3300 and V3800 series, were known for their cold-start reliability and tolerance to winter diesel blends. One operator reported five years of trouble-free winter operation with a Kubota-powered Bobcat, while his newer Doosan-equipped unit struggled every time temperatures dropped below freezing.
Kubota’s mechanical injection systems and simpler fuel filtration made them more forgiving in harsh conditions. In contrast, Doosan’s high-pressure common rail systems, while more efficient and cleaner-burning, were more sensitive to fuel quality and temperature.
Recommendations for Operators in Cold Climates
Some Bobcat dealers began stocking larger quantities of fuel filters during winter and offering service packages that included cold-weather prep. Others recommended switching to alternative models like the Caterpillar 262D, which had fewer reported issues in similar conditions.
In response to growing complaints, some operators began exploring aftermarket solutions, including less restrictive fuel filters and bypass kits. However, these modifications can void warranties and must be approached cautiously.
Conclusion
The integration of Doosan Tier 4 engines into Bobcat skid steers marked a significant shift in the brand’s engineering philosophy. While the engines meet stringent emissions standards and perform well in warm climates, their cold-weather reliability has drawn criticism from seasoned operators. Fuel system sensitivity, filter clogging, and injector costs have made winter operation more challenging than with previous Kubota-powered models. For contractors working year-round in northern regions, understanding these limitations and preparing accordingly is essential to maintaining uptime and avoiding costly delays.
Bobcat, originally founded in North Dakota in the 1950s, became synonymous with compact equipment—especially skid steer loaders. For decades, Bobcat relied heavily on Kubota diesel engines, known for their reliability, cold-start performance, and global parts availability. However, following Bobcat’s acquisition by Doosan Infracore in 2007, a gradual shift began toward integrating Doosan-built engines into Bobcat machines, particularly to meet Tier 4 emissions regulations.
Doosan, a South Korean industrial conglomerate with deep roots in heavy equipment and power systems, developed its own Tier 4-compliant diesel engines to meet EPA standards. These engines were introduced into Bobcat’s S-series and M-series skid steers, including models like the S650 and T770. While the move aimed to streamline manufacturing and reduce dependency on third-party suppliers, it also introduced new challenges—especially in cold climates.
Terminology Clarification
- Tier 4 Emissions: A set of EPA regulations requiring diesel engines to drastically reduce particulate matter and nitrogen oxides.
- Fuel Rail Pressure: The pressure at which diesel fuel is delivered to injectors; critical for atomization and combustion.
- DPF (Diesel Particulate Filter): A filter that traps soot from exhaust gases; requires periodic regeneration.
- Cold Soak: A condition where the entire engine and fuel system are exposed to freezing temperatures for extended periods.
- Winter Blend Diesel: A fuel formulation with additives to prevent gelling in low temperatures.
Operators in northern regions began reporting issues with Doosan-powered Bobcats during winter months. The most common symptoms included:
- Difficulty starting after overnight cold soak
- Frequent fuel filter clogging, even with clean diesel
- Loss of power due to low fuel rail pressure
- Excessive downtime waiting for replacement filters
Another technician observed that injectors on these engines could cost upwards of $800 each, not including labor. A fueling system failure around 2,500 hours was suspected to be linked to inconsistent rail pressure and premature injector wear.
Comparisons to Kubota-Powered Bobcats
Many long-time Bobcat users compared the Doosan engines unfavorably to the Kubota diesels used in earlier models. Kubota engines, particularly the V3300 and V3800 series, were known for their cold-start reliability and tolerance to winter diesel blends. One operator reported five years of trouble-free winter operation with a Kubota-powered Bobcat, while his newer Doosan-equipped unit struggled every time temperatures dropped below freezing.
Kubota’s mechanical injection systems and simpler fuel filtration made them more forgiving in harsh conditions. In contrast, Doosan’s high-pressure common rail systems, while more efficient and cleaner-burning, were more sensitive to fuel quality and temperature.
Recommendations for Operators in Cold Climates
- Use premium winter blend diesel with anti-gel additives during cold months.
- Replace fuel filters proactively before peak winter to avoid emergency downtime.
- Install engine block heaters and fuel line heaters to reduce cold soak effects.
- Monitor fuel rail pressure using diagnostic tools to catch early signs of injector wear.
- Consider switching to alternative models or retrofitting older Bobcats if winter reliability is critical.
Some Bobcat dealers began stocking larger quantities of fuel filters during winter and offering service packages that included cold-weather prep. Others recommended switching to alternative models like the Caterpillar 262D, which had fewer reported issues in similar conditions.
In response to growing complaints, some operators began exploring aftermarket solutions, including less restrictive fuel filters and bypass kits. However, these modifications can void warranties and must be approached cautiously.
Conclusion
The integration of Doosan Tier 4 engines into Bobcat skid steers marked a significant shift in the brand’s engineering philosophy. While the engines meet stringent emissions standards and perform well in warm climates, their cold-weather reliability has drawn criticism from seasoned operators. Fuel system sensitivity, filter clogging, and injector costs have made winter operation more challenging than with previous Kubota-powered models. For contractors working year-round in northern regions, understanding these limitations and preparing accordingly is essential to maintaining uptime and avoiding costly delays.
