This article explains what the Doosan D24 engine is, where it is used, and how Fab Heavy Parts can help when your machine needs parts, an overhaul kit, or a long block replacement. This guide is for Bobcat and compact equipment owners, operators, and service professionals looking for information on the Doosan D24 engine. Understanding the D24 engine helps ensure proper maintenance, efficient repairs, and optimal equipment performance.
Key Takeaways
The Doosan D24 engine is commonly found in Bobcat skid steers and track loaders, especially Tier 4 / Stage V machines.
- The Doosan D24 is a 2.4L, 4-cylinder compact diesel engine used in many Bobcat models, including S450–S650, T450–T650, Toolcat machines, and select excavators.
- The Doosan D24 engine is available in two power options: 61 HP and 74 HP, and the D24 engine produces between 49 and 74 horsepower with maximum torque up to 320 Nm at 1,600 rpm.
- Key benefits include strong low-end torque, lower fuel consumption, a Bosch common rail direct injection fuel system, and EPA Tier 4 Final / Stage V emissions compliance.
- Fab Heavy Parts offers D24 long blocks, overhaul kits, and key components such as liners, pistons, rings, bearings, and gaskets, including references such as 7030394 and 7246280.
- If your Bobcat is already down, scroll to the troubleshooting and repair options first so you can decide whether repair, overhaul, or replacement engine service makes the most sense.
Overview of the Doosan D24 Engine
The Doosan D24 engine is a compact 2.4-liter diesel engine designed for skid steers, track loaders, compact excavators, and other compact equipment. It has been widely used by Bobcat since the early-to-mid 2010s in Tier 4 models. The Doosan D24 is also widely used in compact off-highway construction machinery and agricultural systems where dependable power and clean emissions matter.
At its core, the D24 is a 4-cylinder, liquid-cooled, turbocharged diesel built for long hours, tight engine bays, and tough jobs. It is commonly seen in 61 HP and 74 HP versions, depending on the machine model, emissions package, and calibration. According to industry spec sources such as Lectura Specs, the D24 is a 2.4L inline engine designed for Tier 4 and Stage V applications.
Compared with older pre-Tier 4 engines, the D24 uses more advanced fuel and emissions systems. Older engines were simpler, but they often burned more fuel and produced more smoke. The Doosan D24 engine was developed to maintain usable power while meeting stricter emissions rules in North America and Europe.
From the Fab Heavy Parts point of view, this is one of the most common engines customers ask about for Bobcat S-series skid steers and T-series track loaders. That is why we keep a close view of D24 compatibility, stock, long block options, overhaul kits, and related engine components.
Doosan D24 Engine Specifications & Variants
Key Specifications
This section gives you the main specs to help confirm whether you are working with a D24 engine instead of a D18, D34, or older Kubota-powered unit, though specifications are subject to change without notice depending on design, manufacturing, or operating variations. Always verify the engine tag and serial number before you order parts.
- 2.4 L displacement
- 4 cylinders in-line
- 4-stroke diesel design
- Liquid-cooled system
- Turbocharged aspiration
- Bosch common rail direct injection fuel system
- Electronic control for fuel delivery and emissions
- Cast-iron cylinder block
- Forged steel crankshaft designed to endure demanding workloads
- Compact layout for tight loader and excavator engine bays
The D24 engine features a turbocharged aspiration and a Bosch common rail direct injection fuel system. The Bosch Fuel Injection System helps meter fuel more accurately, which improves machine response, supports higher torque, and helps reduce fuel use.
Power Ratings
Typical power ratings include:
- Around 61HP / 61 HP for many compact Bobcat applications
- Around 74HP / 74 HP for higher-output machines
- General D24 ratings from about 49 to 74 horsepower, depending on market and configuration
- Maximum torque of about 320 Nm at 1,600 rpm in higher-output versions
The Doosan D24 engine is available in two power options: 61HP and 74HP, making it suitable for various compact equipment applications. The Doosan D24 engine is available in two power options: 61 HP and 74 HP, which is why it appears across several different Bobcat and compact equipment classes.
You may also see the engine listed as D24NAP. In simple terms, D24 and D24NAP share the same basic 2.4L block family, but they may use different calibrations, emissions hardware, sensors, manifolds, or auxiliary components. These differences help the engine meet specific Tier 4 Final or Stage V requirements by region.
The D24 is often described as a compact T4F engine. Its small form helps it fit in smaller loaders and excavators without giving up the low-end power needed for hydraulic work.
Common Machines Using the Doosan D24
Correctly identifying where the Doosan D24 engine is used helps you order the right long block, overhaul kit, or matching components. Parts for the Doosan D24 engine can vary based on the specific serial number of the equipment, and users are advised to check the Bobcat Online Parts Catalog for compatibility.
The Doosan D24 engine is commonly used in Tier 4 Bobcat skid steers and track loaders, including models such as S550, S650, S595, T450, T550, T650, and T595.
Common Bobcat Skid Steer Models Using the Doosan D24 or D24NAP
- S450
- S510
- S530
- S550
- S570
- S590
- S595
- S630
- S650
Approximate use years often begin around 2013–2014, depending on region and machine configuration. Still, do not rely only on model year. Always confirm by serial number and engine data plate.
Common Bobcat Track Loader Models Using the D24
- T450
- T550
- T590
- T595
- T630
- T650
The D24 family is also used in certain Bobcat Toolcat models and some compact excavators. In addition to Bobcat equipment, the Doosan D24 engine is also utilized in Doosan excavators, expanding its application range in the construction and landscaping industries.
Information to Have Ready When Contacting Fab Heavy Parts
When contacting Fab Heavy Parts, have this information ready:
- Machine brand and model
- Full machine serial number
- Engine model: D24 or D24NAP
- Emissions label information
- Any part number from the old engine or existing product tag
- Your city, state, and country for delivery planning
This helps us check fit and helps the customer confirm the correct power rating and configuration matches your machine before the order is placed.
Performance, Fuel Efficiency & Emissions
The D24 engine was engineered for strong torque, lower fuel use, and cleaner exhaust in demanding compact equipment work. It is recognized for delivering high low-end torque, robust power, and exceptional fuel efficiency.
Fuel Efficiency
The Bosch common-rail system precisely meters fuel. That improves cold starts, throttle response, and combustion efficiency. The Doosan D24 engine features a Bosch Fuel Injection System, which enhances overall machine performance and provides higher torque.
Operators often notice the D24’s low-end pull. That matters when pushing into piles, lifting heavy loads, grading, or running hydraulic attachments. You do not want the engine to bog down every time the machine meets resistance.
The Doosan D24 engine is designed to achieve lower fuel consumption compared to previous models, enhancing efficiency in various applications. The Doosan D24 engine’s advancements in technology contribute to improved fuel efficiency, which is critical for meeting modern environmental standards.
Emissions Systems
On the emissions side, the Doosan D24 engine complies with Tier 4 emissions regulations, ensuring lower emissions while maintaining performance. Many D24 T4F / Stage V packages use exhaust aftertreatment such as a Diesel Oxidation Catalyst, Diesel Particulate Filter, and sometimes Exhaust Gas Recirculation.
However, not every variant is the same. Some variants of the D24 utilize a Diesel Oxidation Catalyst (DOC) and do not require a Diesel Particulate Filter (DPF). Other variants are equipped with a dpf filter as part of the emissions system.
This matters for city work. The D24 can operate in emission-regulated city centers due to its advanced exhaust after-treatment systems. That is important for contractors working around schools, hospitals, commercial sites, and dense urban jobs.
The next generation of Doosan D24 engine features a Bosch Fuel Injection System that improves overall machine performance and provides higher torque, resulting in lower fuel consumption for the same work output while meeting Stage V emissions regulations.
The trade-off is added complexity. Sensors, DOC units, EGR parts, and DPF systems need proper care. Fab Heavy Parts helps customers balance performance with reliability by supplying quality engine cores, long blocks, and rebuild components tailored to D24 requirements.
Doosan D24 Long Block & Overhaul Options (Fab Heavy Parts Focus)
A long block is a fully assembled engine sub-assembly. It normally includes the block, crankshaft, pistons, camshaft, and cylinder head. It usually does not include bolt-on accessories such as the turbo, fuel pump, wiring harness, starter, alternator, or some manifolds.
Fab Heavy Parts, Inc., offers Doosan D24 and D24NAP long blocks that are ready to accept the customer’s existing accessories. This can reduce downtime for Bobcat skid steers and track loaders in the 61–74 HP range.
Some D24 long blocks are sold with no core return required. That can simplify the purchase, avoid core shipping hassles, and help when the original engine is cracked, broken, or not rebuildable. Other engines may include a core charge that is refunded when a rebuildable core is returned.
The Doosan D24 engine is available in long block and drop-in options, with power ratings of 61HP and 74HP. A drop-in engine, when available, includes more external components and can be closer to a full replacement package.
Fab Heavy Parts also carries overhaul rebuild kits for D24 engines. An overhaul rebuild kit for the Doosan D24 engine includes various components such as cylinder liners, pistons, and gaskets, and is compatible with multiple Bobcat models.
Typical D24 Overhaul Kit Components
A typical D24 overhaul kit may include:
- Semi-finished cylinder liners, including references such as 7030394 and 7246280
- Pistons
- Piston pins
- Rings
- Main bearings
- Rod bearings
- Thrust bearings
- Upper and lower gasket sets
- Intake and exhaust valves
- Valve guides and seats
- Other rebuild components needed for in-frame or out-of-frame work
Note that semi-finished liners require machining. A professional machine shop should measure and finish them correctly before installing.
If you are interested in a D24 long block, rebuild kit, or individual parts, contact Fab Heavy Parts with your machine model and serial number. You can use the quote form on www.fabheavyparts.com, call our team, or send photos of your engine tag. Fast shipping within the USA is available on many in-stock items.
Maintenance Tips & Common Doosan D24 Issues
Proper maintenance is the most important factor in getting long life from a D24 engine. This is especially true because the engine uses high-pressure fuel injection and modern emissions systems.
Maintenance Basics
Here are the basics:
- Follow the oil and filter service schedule.
- Use the correct oil grade for the engine and climate.
- Replace fuel filters on time.
- Keep the cooling system clean.
- Check coolant level and condition.
- Inspect air filters often in dusty work.
- Keep electrical connectors dry and secure.
The D24 engine has a 500-hour oil and fuel filter replacement cycle, reducing equipment downtime. That does not mean you should ignore severe conditions. Dust, heat, cold starts, and poor fuel quality may call for shorter intervals.
Keep the radiator, charge-air cooler, and DPF area clean. Machines working in demolition, agriculture, concrete, or landscaping can pack debris into cooling fins. A plugged radiator can cause overheating fast.
For Tier 4 machines, inspect the dpf filter prior to installing replacement sensors or assuming the problem is electronic. Sometimes the dpf filter needs professional cleaning, especially if the machine has been run at low load for long periods.
Common Maintenance Issues
Common D24 issues include:
- Hard starting from fuel system problems
- Loss of power from dirty filters or clogged aftertreatment
- Overheating from plugged radiators or low coolant
- White, blue, or black smoke from poor combustion
- Oil or coolant contamination
- Internal wear from skipped service
Early models of the D24 faced vulnerabilities related to fuel contamination, which could cause catastrophic failures in the fuel system. Contaminated fuel can damage pumps, rails, and injectors. If you find metal in the fuel filter, stop running the machine and review the full fuel system before replacing one part at a time.
When damage is too severe for simple repair, a new or remanufactured D24 long block may be the fastest path back to work. This is often true with a cracked block, spun bearings, major liner scoring, or severe overheating damage.
Troubleshooting & When to Consider a Long Block Replacement
This section is for owners whose machines are already down or showing serious symptoms. The goal is to help you decide whether a repair, overhaul kit, or long block is the right move.
Warning Signs of Major Internal D24 Issues
- Loud knocking
- Metal in the oil
- Very low compression
- Severe smoking after filter and turbo checks
- Coolant in the oil
- Milky oil
- Heavy crankcase pressure
- Repeated overheating
- Sudden loss of power
Repeated DPF or emissions faults do not always mean the aftertreatment system is the root cause. Poor combustion from worn injectors, low compression, or internal wear can create soot that triggers emissions problems again and again.
If teardown shows damaged crankshaft journals, cracked cylinder liners, badly scored bores, or a broken block, an overhaul kit alone may not be cost-effective. In that case, a fully assembled long block often becomes the smarter replacement engine option.
Repair or Replace? A Simple Guide
Here is a simple way to think about it:
- Minor leaks or external parts failure: repair the failed part.
- Worn pistons, rings, liners, or bearings with a good block and crank: consider an overhaul kit.
- Severe internal damage, cracked castings, or major downtime pressure: consider a long block.
FAQ
Q1: How do I confirm that my machine has a Doosan D24 engine?
A1: Check the engine data plate or sticker on the valve cover, timing cover area, or engine block. Look for D24 or D24NAP. Then cross-check the machine model and serial number in the operator’s manual, service information, or Bobcat Online Parts Catalog. If the tag is damaged or hard to read, send Fab Heavy Parts photos of the engine bay, serial plate, and emissions label. Our team can help identify the correct engine family.
Q2: What is the difference between a D24 long block and a complete drop-in engine?
A2: A D24 long block includes the assembled block, crankshaft, pistons, camshaft, and cylinder head. It usually reuses your existing turbo, fuel system, wiring, starter, alternator, and other accessories. A complete drop-in engine, if offered for your configuration, comes with more components already installed. Long blocks are often more affordable and still reduce labor time compared with rebuilding the engine piece by piece.
Q3: How long does a Doosan D24 engine usually last?
A3: With proper maintenance, clean fuel, correct oil, cooling system care, and attention to DPF or DOC service, many Doosan D24 engines can run several thousand hours. Many well-maintained units reach 6,000–10,000 hours or more before major overhaul. Harsh job sites, skipped service, overheating, or contaminated fuel can shorten that life. That is why Fab Heavy Parts sees a wide range of hour readings on engines needing rebuild or replacement.
FAB Heavy Parts: Your Trusted Engine Parts Supplier
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