How to Inspect a Used Tub Grinder Before Buying

A used tub grinder is a $150K to $600K decision. The brand on the side matters less than what is going on inside the tub. After helping buyers through dozens of these inspections, here is the checklist we walk people through — and the specific things that should kill a deal.

Before you fly out: documentation request

Ask the seller for these items before you book travel. If they cannot or will not produce them, that is information too:

• Service records — minimum the last 12 months, ideally since new
• Hour meter readings for engine AND tub (some grinders track separately)
• Recent inspection photos of hammers, anvil, screens, and tub interior
• Maintenance log for hammer rotations and screen changes
• Any major repair invoices — engine work, hydraulic pump, bearing replacements

A unit with $0 in maintenance receipts over five years is either too good to be true (unlikely) or has been run without paperwork (more likely). Walk away from undocumented machines unless the price is at salvage levels.

On-site inspection — the 90-minute walk

1. Engine bay (15 min)

Look for, in this order:

• Oil leaks under the engine — small drips are normal on machines over 5,000 hours, puddles are not
• Coolant condition — pull the radiator cap, look for oil sheen or sludge (head gasket warning)
• Belts and hoses — cracking, fraying, glaze
• Air filter — fresh and seated, no daylight around the gasket
• Hour meter — confirm it matches paperwork. Disconnect a sensor and walk away if the seller cannot account for a discrepancy

2. Hydraulic system (20 min)

This is where mid-life grinders fail:

• Hose condition — any weeping at fittings, ANY cracking on flex sections
• Tank fluid — should be amber and clean. Milky = water contamination. Black = overheated and burned. Either kills the deal until you know cost.
• Pump noise — start the unit cold and listen. High-pitched whine on startup that does not clear in 30 seconds = bearing wear.
• Cylinder rod condition — any pitting on chrome means failed seals are imminent
• Cooling fan and oil cooler — clean fins, no bent blades

3. Tub interior (30 min — the most important inspection)

Have the seller open the tub. If they refuse, do not buy.

What you are looking for:

• Hammer condition — measure remaining hammer length vs spec. Worn-out hammers are normal at high hours; misaligned hammers from running with broken units are a hydraulic-system tell
• Anvil wear — should be replaceable, but check for scoring deep into the body
• Screen condition — bent, cracked, or hole-burned screens. Most operators replace screens regularly so cosmetic wear is OK
• Tub liner — cracks in the liner that extend into structural wall are a deal-killer
• Discharge belt — splices, tears, condition of the rollers underneath

4. Drum / rotor (15 min)

• Visible damage to the rotor face
• Out-of-balance indicators — uneven wear on hammers across the rotor, the operator pointing out vibration
• Bearing seals — any grease leakage near the rotor shaft ends

5. Control systems (10 min)

Start the unit, run it through a cycle. Modern Morbark, Bandit, CBI grinders all have engine + hydraulic computers that store fault codes. Ask the seller to pull current codes. Stored codes that have been cleared recently are a yellow flag.

What disqualifies a unit immediately

These are non-negotiable walk-away signals:

1. Cracked tub structural wall — repair is uneconomical
2. Milky hydraulic oil — repair scope is unknown, easily $30K+
3. Engine that smokes blue or white at idle — bottom-end work coming
4. Refusal to start the unit cold — they are hiding something
5. Hour meter physically disconnected or mismatched to service records

What is usually fine (and gives you negotiating room)

• Worn hammers — you would replace these in your first 200 hours anyway
• Worn anvil — same
• Cosmetic body damage — you are not buying a parade unit
• Faded paint — irrelevant
• Old screens — easily $2K-$5K to replace
• Dirty cooling system — flush and refill

Each of these is real money but predictable money. A unit with all of these but no structural or engine concerns is a deal at the right price.

What it should cost

Rough used pricing as of June 2026, for buyers wondering where you should land:

• Morbark 6400XT, 3,000-5,000 hrs, good condition: $550K-$700K
• Bandit 4000T, 2,000-4,000 hrs, good condition: $325K-$450K
• CBI 6800CT, 1,500-3,500 hrs, good condition: $700K-$950K

Below those ranges, expect deferred maintenance. Above, expect either freshly rebuilt or premium dealer pricing.

Questions buyers ask before flying out

Q: How much should the seller let me have it inspected?
A: Full access. If they limit you to a walkaround without starting it, walk away.

Q: Do I need a third-party inspector?
A: For under-$300K units, you can do this yourself if you are mechanically literate. For $500K+ units, $1,200 for a qualified independent inspector saves you 50x that in repair surprises.

Q: Can I get warranty on a used grinder?
A: Usually not from the manufacturer, but reputable brokers — including us — will warranty the major components for 90 days. Always ask what the seller stands behind in writing.

Want help walking through one?

RPG Equipment moves tub grinders across North America. If you are looking at a specific unit and want a second set of eyes, call (508) 625-9271. We will tell you what we see, even if it is not a unit we are selling.