Caterpillar 3046 Engine for Sale | CAT 315 320 Excavator Diesel Inline-6

About This Engine

The Caterpillar 3046 is an inline-six direct-injection diesel engine used in Caterpillar’s medium-duty excavator and crawler dozer products from the early 1990s through the mid-2000s. Built under Caterpillar’s manufacturing agreement with Mitsubishi- an arrangement that dates to the 1980s- the 3046 is produced with shared CAT-Mitsubishi engineering standards. Parts for this engine carry both Caterpillar and Mitsubishi part numbers, and buyers sourcing components should be aware that searching under either brand designation may yield the same or compatible parts.

The 3046 family includes two aspiration configurations: the naturally aspirated base version and the 3046T turbocharged variant. The 3046T was used in the CAT 315C excavator where Caterpillar specifically noted it as having the best fuel consumption in its class among diesel engines- a result of improved thermal efficiency and reduced friction between the piston and liners. Both variants share the same fundamental cast iron block-and-head construction with wet-sleeve cylinder liners.

The wet-sleeve liner design is the 3046’s most important practical advantage. Unlike parent-bore engines where the cylinder walls are part of the block and require expensive boring or line-honing to rebuild, the 3046’s liners are removable sleeves that can be replaced individually. This significantly reduces rebuild cost and time, particularly for operators in remote locations or those doing in-frame overhauls without access to full machine shop capabilities.

Signs You Need a Replacement Engine

• Excessive black smoke under load- injector wear, injection timing drift, or turbocharger issues (3046T)
• White smoke on cold start that does not clear- cylinder liner wear allowing oil into combustion, or injector tip carbonization
• Loss of power without obvious external cause- injection pump delivery rate reduction or air restriction
• Overheating- cooling system restriction or water pump failure. Overheating accelerates liner and seal wear.
• Oil in coolant or coolant in oil- liner seal (O-ring at wet-sleeve base) failure- a common wear item on aged 3046 engines
• Fuel consumption increase without corresponding power gain- injector spray pattern degradation on high-hour units

Known Problems With This Engine

• Wet-sleeve liner O-ring seal leakage- the 3046’s most common age-related concern: Each wet-sleeve liner sits in the block on O-ring seals at the base. These seals can harden and leak with age and heat cycling, allowing coolant and oil to mix. We inspect coolant condition and oil for contamination before shipping. O-ring replacement at liner replacement is the correct service.
• Injection pump delivery rate reduction: The mechanical injection pump on high-hour 3046 engines develops wear that reduces fuel delivery rate and injection pressure. Symptoms are power loss and increased fuel consumption. The pump is a serviceable component requiring diesel injection specialist equipment.
• Turbocharger oil seal wear (3046T): The turbocharger on 3046T applications can develop bearing wear and oil seal leakage on high-hour units, causing blue smoke and oil consumption. We note turbocharger condition where applicable before shipping.
• Valve lash drift: The 3046 requires periodic valve lash adjustment. Valve lash on inlet and exhaust is 0.25 mm (approximately 0.010 in) for both. Neglected valve lash causes rough running and reduced performance. We inspect valve train condition before shipping.
• Parts dual-numbering confusion: Buyers ordering replacement parts for the 3046 should be aware that parts are listed under both CAT and Mitsubishi numbers. Using the machine serial number and the engine serial number (5XK prefix most common) is the most reliable way to source correct components.

Caterpillar 3046 Variants

Two aspiration configurations with largely shared internal architecture:

What Is Included- What Is Not Included

Vehicle Compatibility

The Caterpillar 3046 and 3046T were used in the following equipment:

The 3046 uses Caterpillar’s standard equipment mounting architecture for this class. Replacement should be like-for-like using matching serial prefix units. Confirm your machine’s engine serial number before ordering to ensure correct configuration.

Engine or transmission: Caterpillar hydraulic transmission systems- application specific. The 3046 is coupled to hydraulic torque converters and powershift transmissions depending on the equipment application. Confirm your machine’s specific drivetrain before ordering.

Common Names and Search Terms

Used OEM vs Rebuilt- Which Is Right for You?

Used OEM is the right choice for equipment operators who need a cost-effective tested engine with documented serial number and variant confirmed. Our 3046 units are inspected with liner condition, coolant contamination, and turbocharger condition (3046T) assessed before shipping.

A rebuilt 3046 from a CAT-certified rebuilder or authorized CAT Reman exchange makes sense for machines requiring fresh liner seals, new injection components, and full warranty coverage. CAT Reman pricing is typically $4,000 to $9,000 or more. Call us and we can discuss current unit condition.

Condition and Inspection Process

• Full external inspection- block, head, liner protrusion area, coolant hose connections, and all accessible surfaces
• Natural vs turbocharged variant confirmed- 3046 or 3046T documented before every order
• Engine serial number documented- 5XK or other prefix recorded for parts sourcing
• Coolant inspected for oil contamination- wet-sleeve liner O-ring failure indicator
• Oil inspected for coolant contamination
• Valve cover removed where accessible for valve train inspection
• Turbocharger condition noted on 3046T units- oil seepage and shaft play assessed

Mileage and operating hours vary by unit. Where available from the donor vehicle or equipment, we provide this information. Where it cannot be confirmed, we disclose this before your order is placed.

Buyer Tips- What to Know Before You Order

• Document the engine serial number: The 5XK serial prefix (most common) and full serial number are essential for ordering correct replacement parts. CAT and Mitsubishi part numbers may differ- the serial number is the authoritative reference. We document this before shipping.
• Machine serial number for parts ordering: In addition to the engine serial number, the machine serial number (e.g., 315C serial number) is often needed for ordering application-specific components like injection pump arrangements and accessory drives.
• Wet-sleeve liner service: If performing an overhaul on a used 3046, replace all liner O-ring seals at installation regardless of apparent condition. O-ring seal kits are inexpensive- coolant-oil contamination from a failed O-ring is expensive to address after the fact.
• Oil specification: CAT ECF-1 specification or equivalent API CI-4 or higher diesel engine oil SAE 15W-40. Change every 250 operating hours. The 3046 is oil-quality sensitive at the valve train and injection pump.
• Valve lash at installation: Check and adjust valve lash at installation on any used 3046. Inlet and exhaust specification is approximately 0.25 mm (0.010 in) cold.

FAQs

Is the CAT 3046 a Mitsubishi engine?