Komatsu PC20-7 Excavator Complete Engine Assembly (3D84N-2H, OEM YM129158-77010)

Tatan Machinery supplies professionally remanufactured Komatsu 3D84N-2H diesel engine assemblies engineered specifically for Komatsu PC20-7 mini hydraulic excavators (applicable for machine serial numbers 35001 and up). Built upon the bulletproof Yanmar 3TN84 / 3TNE84 industrial architecture, this 1.4L 3-cylinder mechanical power plant is remanufactured strictly to OEM tolerances with 100% brand-new internal wear components. This page details verified compact diesel specifications, 2.6-ton trenching failure diagnostics, workshop bench-testing standards, and field installation rules for equipment hire companies, landscaping contractors, and mini plant workshops.

Supplier Information & Build Status

Remanufacturing Standard: Precision Rebuilt for 3D84N

Compact 3-cylinder excavators run hard under continuous throttle. We do NOT sell salvage yard pulls. Every 3D84N-2H engine is completely stripped and rebuilt with 100% brand-new internal wear parts:

• Block & Head Core Verification: Cylinder block and head undergo chemical carbon stripping, ultrasonic cleaning, and pressure hold tests. Fire deck precision milled flat.
• 100% Brand-New Wear Components Installed: Brand-new 84mm pistons, complete piston ring sets, cylinder liner sleeves, connecting rod bushings, main bearings, rod bearings, and thrust washers.
• Precision Crankshaft Re-Machining: Forged crankshaft journals micropolished and dynamically balanced to factory runout specifications.
• 100% Brand-New Gasket & Seal Pack: Premium cylinder head gasket, front timing cover seal, and rear crankshaft main seal replaced to prevent oil weeping into the bellhousing.
• Mechanical Injection Pump Calibration: Mechanical fuel injection pump elements inspected, recalibrated on a bench, and fuel injectors fitted with new nozzles for clean atomization.

When to Replace the 3D84N Engine on Komatsu PC20-7: Field Diagnostics

The Komatsu PC20-7 operates at substantial hydraulic flow for its compact size, frequently working with trenching buckets or mini hydraulic breakers. When major mechanical failure occurs, replacement is the fastest path back to revenue:

• Connecting Rod Bearing Knock from Slope Work: Operating on steep foundation trenches with low engine oil capacity (~3.8L) causes momentary oil pickup starvation, spinning rod bearings and gouging the crankshaft.
• Cooling System Choking & Blown Head Gasket: Fine excavation dust, tree roots, and grass chaff block the small radiator core. Chronic overheating warps the cylinder head and pushes compression into the coolant reservoir.
• Hydraulic Load Bogging from Injection Pump Wear: Worn pump plungers failing to deliver sufficient fuel pressure when dual hydraulic pumps stroke up, causing the engine to heavily lug down or stall when lifting the boom.
• Heavy Blow-by & Cold Starting Failure: Cylinder bore wear and stuck compression rings venting combustion smoke through the breather pipe, resulting in complete compression loss on cold mornings.

Workshop Testing Standards (Pre-Delivery Inspection)

Every remanufactured Komatsu 3D84N engine undergoes 5-step quality verification before packaging:

1. Manual Crankshaft 720° Barring Test: Smooth rotation verification without valvetrain binding or mechanical interference.
2. Mechanical Fuel Pump Timing & Plunger Check: Verification of fuel spill timing and injection nozzle atomization pattern.
3. Lube Oil Gallery Pressure Priming: Pre-filling the oil circuit to confirm pressurized flow through main journals and valvetrain.
4. Block & Head Pneumatic Leak Hold Test: Air hold test to guarantee cylinder head gasket and water jacket sealing integrity.
5. Flywheel Coupler Concentricity Dial Check: Ensuring 100% true alignment for the hydraulic main pump drive coupling.

Export Heavy-Duty Packaging Process

Although compact, the 3D84N is packed to full industrial export standards to survive rough ocean and air cargo transit:

• Internal & External Anti-Rust Preservation: All raw machined surfaces, crankshaft snout, and flywheel teeth coated with high-grade anti-corrosion grease.
• Dust Caps on All Openings: Intake manifold, exhaust elbow, water inlets, and fuel feed fittings sealed with heavy-duty protective plugs.
• Direct Sump-Skid Bolting: The engine is anchored securely to heavy timber base skids through rigid mounting brackets.
• ISPM 15 Fumigation-Free Solid Crate: High-density export plywood crate secured with galvanized steel strapping.

Actual export wooden crate packaging and internal skid bracing for 3D84N

Global Shipping & Customs Documentation

Fast, reliable dispatch tailored for commercial contractors and parts wholesalers worldwide:

• Emergency Machine Down (AOG Freight): Priority air cargo via DHL Aviation, FedEx Heavy Cargo, or direct airline belly freight within 3–7 business days.
• Ocean Container Freight (LCL / FCL): Consolidated container shipping to all major commercial seaports worldwide.
• Complete Export Documents: Commercial Invoices with correct HS Code (8408.20), Packing Lists, and Certificates of Origin for smooth customs clearance.

Container loading and air freight dispatch supported by global logistics partners

Critical Installation Guidelines (PC20-7 Mechanic Checklist)

To prevent instant damage to your newly installed engine, technicians MUST adhere to these procedures:

1. Thorough Radiator Core Deep-Cleaning: Remove the compact radiator and chemically reverse-flush both internal passages and external aluminum cooling fins. Installing a fresh engine with dirty cooling fins will cause immediate thermal head distortion!
2. Hydraulic Pump Spline Coupler Alignment: When remounting the hydraulic main pump to the 3D84N bellhousing, verify the internal rubber/nylon drive coupling. NEVER force the pump into place using mounting bolts; slide it flush by hand before torquing.
3. Mechanical Fuel Pump Air Bleeding: The in-line pump delivery valves are sensitive to air pockets. Pump the primer on the fuel-water separator base until clear, bubble-free diesel flows from the pump bleeder screw. Never crank a dry pump!
4. Engine Stop Solenoid Travel Check: Verify that the 12V fuel shutoff solenoid operates freely. If the solenoid plunger does not fully extend or bind against the linkage, the engine will either fail to start or fail to shut off.
5. Initial Oil Fill & Filter Priming: Pre-fill the new spin-on oil filter with 15W-40 oil. Disconnect the stop solenoid wire and crank the starter motor in 10-second intervals until the instrument cluster oil pressure lamp extinguishes.

Buyer Frequently Asked Questions (Purchasing FAQ)

🔗 Frequently Purchased Together with Komatsu PC20-7 Diesel Engine:

• MAIN VALVE:
  Main Control Valve Assembly for Komatsu PC20-7 Excavator
  100% Brand New
• HYDRAULIC PUMP:
  Main Hydraulic Pump Assembly for Komatsu PC20-7
  100% Brand New
• TRAVEL MOTOR:
  Final Drive Travel Motor Assembly for Komatsu PC20-7
  100% Brand New
• BRAND CATALOG:
  View All Komatsu Excavator & Heavy Equipment Parts Collection

Get Wholesale Factory Quote for 3D84N-2H PC20-7 Engine

Looking for direct factory pricing, stock availability, or technical verification for Komatsu 3D84N engines? Contact senior specialist Gavin now!

💡 Fast Quote: Send your engine serial number or nameplate photos for an accurate match within 10 minutes!