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

Description

Engine Background

The Caterpillar 3046 is an inline-six direct-injection diesel that found service in Caterpillar’s medium-duty excavator and crawler dozer products from the early 1990s into the mid-2000s. It is a product of Caterpillar’s longstanding manufacturing agreement with Mitsubishi, an arrangement going back to the 1980s. Engines and parts in this line carry both CAT and Mitsubishi part numbers, and buyers sourcing replacement components should be aware that searching under either brand designation may yield the same or compatible parts.

The 3046 family covers two aspiration configurations: the naturally aspirated base engine and the 3046T turbocharged variant. The 3046T was the powerplant in the CAT 315C excavator, where Caterpillar specifically called out best-in-class diesel fuel consumption thanks to improved thermal efficiency and reduced piston-to-liner friction. Both aspiration variants share the same cast-iron block-and-head construction with wet-sleeve cylinder liners.

That wet-sleeve liner design is the 3046’s most practical advantage. Unlike parent-bore engines where the cylinder walls are part of the block and need expensive boring or line-honing to rebuild, the 3046’s liners are removable sleeves that swap individually. Rebuild cost and time both drop significantly, which matters especially for operators in remote locations or anyone performing an in-frame overhaul without full machine shop support.

When Replacement Becomes Necessary

• Heavy black smoke under load, generally pointing to injector wear, injection timing drift, or turbocharger issues on 3046T applications
• White smoke at cold start that does not clear with warm-up, usually liner wear admitting oil into combustion or injector tip carbonization
• Loss of power without an obvious external cause, typically injection pump delivery rate reduction or an air restriction
• Overheating from cooling system restriction or water pump failure, which accelerates liner and seal wear if not corrected
• Oil in coolant or coolant in oil, indicating wet-sleeve liner O-ring seal failure, a common 3046 aging item
• Rising fuel consumption without matching power gain, usually injector spray pattern degradation on high-hour units

Known Weak Points

• Wet-sleeve liner O-ring seal seepage, the 3046’s most common age-related concern: each wet-sleeve liner seats in the block on O-rings at the base. These seals harden and leak with age and heat cycling, allowing coolant and oil to mix. We inspect coolant condition and oil for contamination on every unit. 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 drops fuel delivery rate and injection pressure. Symptoms are power loss and rising fuel consumption. The pump is a serviceable component but requires diesel injection specialist equipment.
• Turbocharger oil seal wear on 3046T applications: the turbocharger on 3046T units develops bearing wear and oil seal leakage on high-hour examples, producing blue smoke and oil consumption. Turbocharger condition is noted on every applicable unit before shipment.
• Valve lash drift: the 3046 requires periodic valve lash adjustment. Both inlet and exhaust spec at 0.25 mm (approximately 0.010 in). Neglected lash causes rough running and reduced performance. We inspect valvetrain condition before shipment.
• Parts numbering confusion: buyers ordering replacement parts for the 3046 should know that parts list under both CAT and Mitsubishi numbers. Using the machine serial number alongside the engine serial number (5XK prefix is the most common) is the most reliable way to source correct components.

Caterpillar 3046 Variants

Two aspiration configurations with largely shared internal architecture:

What Ships and What Does Not

Direct-Fit Equipment Applications

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

Not sure if this fits? Call us. We verify fitment before every order ships and document the engine serial number for parts compatibility.

Search Terms Buyers Use

Caterpillar 3046 | CAT 3046 engine | CAT 3046T turbocharged | CAT 315C engine | CAT 320 engine | CAT excavator diesel | Mitsubishi 6D14 | 5XK engine | CAT dozer diesel | CAT-Mitsubishi diesel

Used OEM Versus Specialist Rebuild

For a working CAT 315C, 315BL, 933C, D3C, or D4C with engine failure, used OEM is the cost-effective path. Our units ship with serial number documented, liner condition assessed, and aspiration variant confirmed. A specialist rebuild makes sense for an in-frame overhaul on a high-value machine where downtime is the constraining factor. Wet-sleeve liner replacement and bearing service typically runs $8,000 to $14,000 from established CAT diesel shops. Call to discuss what fits your situation.

Inspection Workflow

• External visual inspection of block, head, and accessible internal areas
• Coolant condition checked for oil contamination, the wet-sleeve seal failure indicator
• Oil inspected for coolant contamination
• Aspiration variant confirmed: 3046 naturally aspirated or 3046T turbocharged
• Engine serial number recorded for parts compatibility (5XK prefix most common)
• Valvetrain condition assessed where accessible
• Turbocharger condition noted on 3046T applications where present

Operating hours vary by unit. Where available from the donor machine we provide them. Where they cannot be confirmed, we disclose this before the order is placed.

Pre-Purchase Buyer Notes

• Confirm aspiration variant against your application: a 3046 going into a 3046T position will not produce expected power. A 3046T going into a 3046 position is usually fine mechanically but you may have intake and exhaust matching to address.
• Service the cooling system at installation: wet-sleeve diesels are sensitive to coolant condition. Flush the system, replace the thermostat, inspect hoses, and use the correct CAT-spec antifreeze concentration.
• Plan injection service: high-hour 3046 injection pumps benefit from a specialist bench test at installation to verify delivery rate. Cheaper to address while the engine is out than after install.
• Source parts under both brands: parts catalogs list components under both CAT and Mitsubishi numbers. Cross-reference both before ordering to avoid duplicate-purchase mistakes.
• Match the machine serial number: equipment-specific accessories (oil pan, intake configuration, hydraulic pump drive) vary by machine. Provide your machine serial number on the call so we ship the closest-fit unit.

Why Buy From Part Nests

• Aspiration variant confirmed: 3046 naturally aspirated or 3046T turbocharged documented before payment
• Engine serial number recorded on every order for parts compatibility
• Wet-sleeve liner condition assessed, the 3046’s primary aging concern
• Coolant and oil cross-contamination check on every unit
• Specialist heavy-equipment freight handling
• No core return required
• Free freight pallet delivery to every state
• 15 day replacement warranty against internal defects
• Call us to speak with someone who understands CAT-Mitsubishi parts sourcing, wet-sleeve service, and equipment-application matching

Additional Reference