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OEM-Spec Mitsubishi Cylinder Blocks: Fix 4D56 & S6K Spun Bearings

High-Density Cast Iron Short Blocks for Mitsubishi Industrial & Commercial Fleets

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Quick Summary: Mitsubishi Cylinder Blocks

Wholesale Mitsubishi Cylinder Block castings for 4D56, 4M40, and S6K engines. Engineered to support Mitsubishi Triton L200 pickups, CAT 320 Excavators, and Fuso Canter trucks. Our HT250 high-density cast iron blocks feature CNC-milled decks and perfectly align-honed main bearing saddles to permanently resolve catastrophic spun bearing failures and thermal warping. Factory direct supply. Contact us for bare block and short block assembly wholesale pricing.

Structural Foundation: Engine Block Reliability for Mitsubishi Heavy Industries

Mitsubishi’s engineering DNA stretches from aggressive 4×4 rally vehicles to the world’s most demanding earthmoving and marine applications. The cylinder block is the massive structural foundation that absorbs this immense combustion pressure and torsional stress. Ruich Value resolves catastrophic bottom-end failures with a wholesale inventory of robust Mitsubishi Cylinder Blocks. Whether you are replacing a cracked block on a Mitsubishi Pajero (4M40) or recovering from a destroyed main bearing saddle in a CAT 320 excavator (S6K), our castings provide the rigid alignment necessary for a lifetime of heavy-duty service. In high-torque industrial diesels, extended oil drain intervals or severe overheating can cause a main bearing to “spin.” This friction-welds the bearing to the crankshaft and gouges the cast iron block beyond the limits of line-boring repair. Our replacement engine blocks are poured from premium HT250/HT300 equivalent grey iron alloys to resist thermal distortion. Every block undergoes multi-axis CNC machining to ensure exact cylinder bore geometry, precise deck flatness, and is supplied with its own matched, factory align-honed main bearing caps.

💡 Pro Tip: Complete Bottom-End Overhaul

Replacing a cylinder block is the most labor-intensive repair in diesel mechanics. To ensure perfect oil clearances and prevent premature failure of your new casting, aggressively inspect and pair it with these wholesale components from our catalog:
  • Mitsubishi Cylinder Heads (Ensure perfect top-deck sealing; an old, warped head will prevent the MLS gasket from sealing against your new block’s CNC-milled deck)
  • Mitsubishi Crankshafts (Pair your new align-honed main saddles with a fresh, micro-polished Ra 0.2 crankshaft to guarantee perfect hydrodynamic oil film)
  • Mitsubishi Cylinder Liners (For blocks requiring sleeves like the 4D56 or S6K, matching liners ensure perfect piston-to-wall clearances)
  • Mitsubishi Camshafts (Critical for OHV block-mounted cam engines to ensure the cam tunnel bearings align perfectly)

Technical Features of Ruich Value Mitsubishi Engine Blocks

  • Align-Honed Main Journals: Every block is supplied with its original, matched main bearing caps, torqued and align-honed to precise OEM specifications to ensure the crankshaft spins freely without binding.
  • CNC Deck Milling: The cylinder deck is CNC machined to an ultra-fine Ra finish, guaranteeing a perfect, leak-free seal when using Multi-Layer Steel (MLS) head gaskets under extreme 4D56 turbo-diesel pressures.
  • High-Density Cast Iron: Manufactured using premium HT250 alloy that aggressively resists thermal cracking between the cylinders and coolant jackets, a common issue in heavily lugged S6K and S4S industrial engines.
  • 100% Pressure Tested: Each bare block is subjected to rigorous hydrostatic pressure testing to verify the integrity of the oil galleries and water jackets, ensuring zero internal cross-contamination.
  • Exact Bore Tolerances: Cylinder bores are precision-machined to accommodate standard-size pistons or standard thin-wall liners, dramatically reducing prep time for local machine shops.

Available Mitsubishi Cylinder Block Catalog

Explore our comprehensive catalog of replacement bare blocks and short block assemblies. We provide robust solutions for Mitsubishi’s commercial trucks, 4x4s, and heavy industrial machinery.
Primary_Part_NumberCross_Ref_Part_NumbersEngine_ModelMachine_Model
MD3048261050A045, MD376993Mitsubishi 4D56Mitsubishi Triton
34407-00302212-8495CAT S6KCAT 320

Explore our complete Mitsubishi Engine Parts Catalog.

Compatible Equipment Models

Mitsubishi Cylinder Blocks fit machinery including Mitsubishi Triton / L200 (4D56), Mitsubishi Pajero (4M40, 4M41), CAT 320B/320C Excavators (S6K / CAT 3066), Mitsubishi FD20-30 Forklifts (S4S), and Fuso Canter Trucks (4D34, 4M50). Contact us with your engine ID to verify bare block vs. sleeved short block availability.

Technical FAQ: Mitsubishi Cylinder Blocks

How do I fix a spun main bearing on a Mitsubishi 4D56 block?

Symptom: Severe, deep knocking from the bottom end, low oil pressure, and the engine seizing. Diagnosis: A spun bearing occurs when the oil film breaks down. Friction welds the bearing to the crankshaft, which then spins the bearing inside the cast-iron block’s main saddle, deeply gouging it. Solution: Once the main saddle is heavily damaged, line-boring is often too expensive or alters gear train backlash. Replacing it with our new 4D56 block, which comes with factory align-honed main caps, instantly restores perfect bottom-end geometry.

Are the main bearing caps included with the S6K / CAT 320 cylinder block?

Answer: Yes, absolutely. Main bearing caps are completely unique to each individual engine block and can NEVER be swapped between different engines. Every Ruich Value Mitsubishi/CAT S6K cylinder block is supplied with its factory-matched set of main caps. They are bolted and align-honed together during manufacturing to ensure a perfectly straight tunnel for the crankshaft.

Do your Mitsubishi 4M40 engine blocks come with cylinder liners installed?

Diagnosis: The 4M40 engine, commonly used in the Pajero, originally utilizes a dry-sleeve (Chromard liner) design. Solution: We offer flexible wholesale options depending on your rebuilding facility’s capabilities. We can supply the 4M40 block completely “bare” (ready for your local machine shop to press and hone your own sleeves), or pre-fitted with standard-size dry liners. Please specify your preference when requesting a quote.

What are your wholesale shipping terms for heavy engine castings?

We provide factory-direct wholesale pricing tailored for engine rebuilding facilities, heavy machinery repair shops, and parts distributors. Standard payment terms include T/T and L/C. Due to the extreme weight of bare blocks, shipments are exclusively handled via LCL or FCL sea freight. Every block is generously coated in anti-rust preventative compound, sealed in VCI plastic, and securely bolted inside export-grade wooden crates to prevent transit damage.

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