Key Points to Know Before Buying a Used Mini Excavator

[MikePhua]

In this discussion, the original poster asked a very practical question:

“I’m planning to buy a used mini excavator. What should I pay attention to? What parts should I check?”

Many experienced owners and contractors shared the following useful advice:
✅ 1️⃣ Check the Hydraulic System
The most critical part of a mini excavator is whether the hydraulic system leaks or has any jittering or sticking.
Pay close attention to: the main pump, control valve, cylinders, and hydraulic hoses for any seepage, cracks, or leaks.
Operate all machine functions fully to ensure smooth and stable motion without shaking.
✅ 2️⃣ Inspect Pins and Bushings for Wear
The working attachments mostly connect via pins. Looseness here affects precision and digging force.
Check for abnormal noise or excessive play in connections on the boom, arm, bucket, and swing bearing.
Slight play is normal, but large looseness means serious wear, which can be costly to repair.
✅ 3️⃣ Examine the Engine
Does it start smoothly? Be cautious if it’s hard to start cold or produces black smoke.
Listen for steady running and absence of knocking noises.
Check for oil, coolant, or air leaks around the engine.
✅ 4️⃣ Check the Undercarriage and Tracks
Look at track wear and tension.
Is the machine veering when driving or making abnormal noises?
Inspect rollers, sprockets, and idlers for excessive wear.
✅ 5️⃣ Inspect the Swing Mechanism
Swing motor and large ring gear damage repairs are expensive.
Check if the swing is smooth without sticking or noise.
Look for hydraulic leaks in this area.
✅ 6️⃣ Verify Operating Hours and Their Accuracy
Hour meters can be tampered with, so treat them as a reference only.
Judge overall machine condition by the wear on the exterior and cabin interior.
✅ 7️⃣ Test Run the Machine
Try operating the machine for at least 20–30 minutes under various working conditions:
Operate multiple controls simultaneously to check for sticking.
Drive around to test smoothness and idling stability.
Check for leaks or power loss after the machine warms up.
✅ 8️⃣ Other User Tips
It’s best to bring an experienced person or hire a professional inspector before buying to avoid future trouble.
Many recommend avoiding “gray market” or heavily refurbished machines imported unofficially, as repairs can be troublesome later.

---

Summary
Used mini excavators are affordable but have many pitfalls. The major components to carefully inspect are the hydraulic system, engine, undercarriage, pins, and swing system.
Buying a machine with maintenance records and a reliable source is strongly advised.