Buying Used Iron? Check These Before You Pay

Every used machine has a story, and the seller is telling you the good half. Here's what to check yourself, what needs a mechanic, and the findings that should end a deal on the spot.

Why Used Equipment Goes Wrong

The problem with buying used iron isn't that sellers lie, most don't. It's that the expensive failures on heavy equipment are invisible in a parking-lot walk-around, and they're invisible in exactly the same way on a good machine and a bad one.

A dozer with 80% undercarriage wear and one with 20% look identical from thirty feet. A hydraulic system with a tired pump works fine for the ten minutes a buyer runs it cold in a yard. Nobody has to deceive you for you to buy a very expensive problem.

What You Can Check Yourself

Fluids first, before anything is started

This is the highest-value ten minutes of any inspection, and you can do it in a yard with a rag.

• Engine oil. Milky means coolant. Fuel smell means injector or pump problems. Fresh oil on a machine being sold isn't automatically suspicious, but it does mean you've lost your best diagnostic sample.
• Coolant. Oil film on the surface, rust, or sludge are all findings.
• Hydraulic oil. Look for milkiness and smell for burnt oil. Glitter in the oil means something is wearing out somewhere in the system.
• Final drive and swing drive oil. If you can get the plugs out, do it. This is where the most expensive surprises hide.

The undercarriage on tracked machines

On a dozer or excavator, undercarriage is one of the largest ownership costs, and a worn one can represent a very large fraction of what you're paying for the machine. Look at pin and bushing wear, sprocket tooth profile, hooked, pointed teeth mean it's late, idler and roller condition, and whether rollers are leaking. Uneven wear side to side suggests alignment or tension problems that will eat the new components too.

Signs of a hard life

• Cracked and re-welded structural areas, especially at the boom, stick and attachment points. Fresh paint over a weld is a specific red flag.
• Bent cylinder rods, or rods with pitting and scoring that will destroy new seals.
• Missing guards, shields and cooler shrouding, these get left off after repairs and cause overheating.
• A hand-painted or unusually clean machine that's otherwise clearly worked. Paint hides leaks.
• Rodent nests, chewed harnesses and corroded connectors on anything that sat.

Run it properly

• Cold start it yourself, watching the exhaust. Excessive white or blue smoke that doesn't clear is a finding.
• Bring it to operating temperature and watch the gauges the whole time.
• Cycle every hydraulic function to both ends of travel, listening for changes and watching for drift.
• Hold a load and see if it sinks, that's a cylinder bypassing internally.
• Travel it, turn it both directions, and listen at each corner for a whine that tracks with travel speed.
• Check for blowby at the crankcase breather with the engine warm and working.

What Needs a Mechanic

These are the checks that require tools and experience, and they're the ones covering the largest dollar amounts:

• Hydraulic pressure and flow testing. The difference between a healthy pump and a tired one doesn't show up in a yard demo. It shows up on a flow meter.
• Diagnostic scan and stored fault history. Codes that were cleared last week still leave traces on many platforms, active codes, pending codes, and event history tell you what the machine has actually been doing.
• Emissions system status on newer trucks and equipment. Soot and ash load, DEF system health, and whether anything has been tampered with. A tampered emissions system on a California road vehicle is a serious problem to inherit. It will fail Clean Truck Check and it is illegal to operate.
• Blowby measurement rather than eyeballing it.
• Oil sample analysis from the engine, hydraulics and final drives. Lab results turn guesswork into data on wear metals and contamination.
• Undercarriage measurement with proper gauges rather than a visual estimate, so you know the actual percentage remaining.

Findings That Should End a Deal

• Coolant in the oil or oil in the coolant.
• Metal chips in hydraulic or final drive oil.
• Structural cracks or repairs in load-bearing areas.
• Tampered or missing emissions equipment on a road-going vehicle.
• A seller who won't let you warm it up, work it, or bring your own mechanic.
• Serial plates that are missing, altered, or don't match the paperwork.

Auctions Are a Different Game

Auction machines are typically sold as-is with no recourse and a short inspection window, which raises the value of getting someone qualified in front of the machine before the sale rather than after. Set your number based on what the inspection found, add the repairs you already know it needs, and stop bidding there. The most expensive equipment purchases we see are the ones made by someone who fell in love with a machine in the ring.

We'll Look At It Before You Buy

All Mechanical does pre-purchase inspections across the Bay Area: San Jose, Fremont, Oakland, Livermore, Stockton and the surrounding area. Dealer-trained diagnosis, real testing rather than a walk-around, and a straight report on what the machine actually needs.

It's a lot cheaper than finding out afterward. Get in touch or call (925) 858-8630 before the sale date.

Frequently Asked Questions

Is a pre-purchase inspection on used equipment worth it?

On any machine costing real money, yes. A single missed final drive, hydraulic pump or emissions problem typically costs several times what an inspection does, and a documented inspection also gives you leverage to negotiate the price down on what it finds.

What are the biggest hidden costs on used heavy equipment?

Undercarriage wear on tracked machines, final drives, hydraulic pump condition, emissions system status on newer trucks and equipment, and deferred maintenance that has been papered over for the sale. All five are expensive and none are obvious from a walk-around.

Can you inspect equipment at an auction yard?

We are mobile across the Bay Area and can inspect where the machine sits, subject to the yard's access rules and timing. Contact us before the sale date so there is time to arrange access, auction windows are tight.

Do low hours mean a machine is in good shape?

Not on their own. A machine with low hours that sat outside for years can have seized components, rotted seals, contaminated fluids and rodent damage to wiring. Duty cycle and maintenance history tell you far more than the hour meter, and hour meters can be replaced.

What should I ask the seller for?

Service records, fluid analysis history if any exists, the reason for sale, and permission to run the machine through its full range of functions at operating temperature. Hesitation on any of those is information in itself.