How to Replace Engine Mounts on a Komatsu PC200 Excavator (Step-by-Step Guide)

Before You Start: Tools, Parts, and Safety

Replacing engine mounts on a Komatsu PC200-8 (and similar PC200LC-8, PC210-10, PC220-8 models) is a straightforward maintenance procedure that can be completed by a qualified heavy equipment mechanic in 3-6 hours. No special Komatsu tools are required, but proper planning and safety precautions are essential when working around a multi-tonne diesel engine suspended on a jack.

Required Parts

• Complete engine mount set: 20Y-54-39520 and/or 17A-54-46120 / 17A-54-46130 (verify against your serial number)
• New mounting bolts and lock washers (recommended — inspect existing hardware for stretch and corrosion)
• Thread-locking compound (Loctite 242 or equivalent medium-strength)

Required Tools

• Hydraulic engine support jack or overhead crane (minimum 2-tonne capacity)
• Socket set: 17mm, 19mm, 22mm, 24mm (metric)
• Calibrated torque wrench (50-200 Nm range)
• Breaker bar for frozen bolts
• Penetrating oil (PB Blaster or equivalent)
• Wire brush and solvent for cleaning mounting surfaces
• Silicone spray (do NOT use petroleum-based lubricants on rubber)

Safety Precautions

• Park the excavator on level, firm ground with the boom lowered and bucket flat on the ground
• Shut down the engine and allow it to cool for at least 30 minutes
• Disconnect the battery negative terminal
• Never work under an engine supported only by a hydraulic jack — use secondary support (jack stands or blocking)
• Two-person operation recommended for alignment and safety

Step 1: Access the Engine Mounts

Open the engine compartment access panels on both sides of the revolving frame. On the PC200-8, the engine mounts are visible at the base of the engine block where it meets the revolving frame rails. Depending on the serial number, there may be 3 or 4 mount points — typically two forward mounts and one or two rear/transmission mounts.

Photograph the existing mount arrangement before disassembly for reference during reassembly. Note the orientation of any asymmetric mounts and the routing of any hoses or harnesses that pass near the mounting area.

Step 2: Support the Engine

Position the hydraulic engine support jack beneath the oil pan (use a wooden block to distribute the load and prevent oil pan damage) or attach a sling to the engine lifting eyes if using an overhead crane. Raise the support until it just contacts the engine — do not lift the engine at this stage. The support is a safety measure to prevent the engine from dropping when the mounts are removed.

Critical: Ensure the engine is only supported, not lifted. Lifting the engine at this point can stress hydraulic hoses, electrical connections, and the exhaust system.

Step 3: Remove the Old Mounts

Apply penetrating oil to all mounting bolts 15-20 minutes before removal. Engine mount bolts on excavators are often corroded and seized due to exposure to heat, moisture, and vibration over thousands of hours. Use a breaker bar if necessary — do not use impact wrenches near the rubber elements as the shock loading can damage adjacent good mounts.

Remove bolts in a cross-pattern sequence (front-left, rear-right, front-right, rear-left) to avoid suddenly shifting the engine's weight to a single mount point. As each mount is unbolted, the engine will settle slightly onto the support jack.

Once all bolts are removed, carefully extract the old mounts. Inspect the mounting surfaces on both the engine block bracket and the frame rail for corrosion, cracks, or elongated bolt holes. Clean all surfaces with a wire brush and solvent wipe.

Step 4: Install the New Mounts

Position the new mounts on the cleaned frame rail mounting surfaces. If the mounts have directional markings (an arrow or "UP" stamp), orient them correctly. Apply a thin film of silicone spray to the rubber surfaces if needed to ease alignment — never use petroleum-based lubricants which will attack the natural rubber compound.

Use the engine support jack to raise or lower the engine slightly to align the mounting bolt holes. Install all bolts finger-tight first, then torque in a cross-pattern sequence to the values specified in your PC200 shop manual (typically 130-160 Nm for M16 bolts — verify against your specific serial number's service data).

Apply medium-strength thread-locking compound to the bolt threads to prevent vibration-induced loosening.

Step 5: Final Checks and Run-In Period

After installation:

• Remove the engine support jack
• Verify all bolts are torqued to specification
• Check clearance between the engine and all adjacent components (fan shroud, radiator hoses, exhaust, wiring)
• Reconnect the battery and start the engine — observe for excessive movement or unusual sounds
• Run the engine at idle for 10 minutes, then at working throttle for 10 minutes
• Shut down and re-check all bolt torques

50-Hour Re-Torque: New rubber mounts undergo a slight settling period during initial use. Re-torque all mounting bolts after the first 50 operating hours. This is the single most important step that mechanics commonly skip — and skipping it is the leading cause of premature mount loosening on new installations.

Order Replacement Mounts for Your PC200

We supply ISO 9001:2015 certified replacement engine mounts for all Komatsu PC200 to PC350 series excavators:

Not sure which part number your machine requires? Send us your model and serial number for free cross-reference verification within 24 hours.

Frequently Asked Questions