How to inspect a used excavator before you buy it

Most people inspect a used machine in the wrong order. They walk up to it, look at the paint, start it, listen to it, work the boom a bit, and then — an hour in, having already half decided — ask about the papers.

Do it the other way around. The checks that can end the visit go first.

1. Documents, before anything mechanical

This takes twenty minutes and it can save you the whole day.

• Chassis and engine numbers, physically stamped on the machine, read with a torch and compared to the paperwork. Not the plate — the stamping. Plates are easy to move.
• The purchase invoice chain. Who bought it new, who has owned it since.
• Hypothecation status. Is there a loan on it, is it closed, and can the financier’s NOC actually be obtained? “It’s closed, I’ll get the NOC” is the single most common reason a machine deal collapses three weeks later.
• Insurance validity, and whether there have been claims.
• Form 29/30 readiness on registrable units.
• Any court attachment or lien.

Mechanical condition is irrelevant if the machine cannot legally transfer to you. A machine with a perfect engine and an unreleased hypothecation is not a bargain; it is somebody else’s problem being handed to you.

2. The machine must be cold

This is the one condition worth being difficult about.

A pre-warmed engine hides hard starting, start smoke, crankcase blowby and injector behaviour. That is precisely why sellers warm them, and a seller who has warmed the machine before you arrive has told you something for free.

Arrange the visit so nothing has run that morning. If you arrive and the bonnet is warm, you have two options: come back another day, or accept that start condition cannot be assessed and write that down so you do not later forget you never saw it.

You get one cold start. Do not waste it fiddling with your phone camera — decide beforehand who is filming and from where.

What to watch, in the first thirty seconds:

• How long it cranks before it fires, and whether it needs the throttle held.
• Smoke colour, and how long it takes to clear. Blue is oil. White is coolant or injection timing. Black is fuel or air.
• Any knock that fades as it warms, and any that does not.

3. The undercarriage — measure it, do not look at it

On a tracked machine this is usually the largest single deferred cost, and it is the item most often described rather than measured. “Tracks look alright” cannot be taken off a price. “Shoes at 34% remaining and the sprockets are hooking” can.

Measure, in this order:

1. Grouser height against the new specification, on three shoes in the middle of the track run, on level ground. Use the lowest reading. Our calculator will turn that into a percentage.
2. Link height — the chain itself, which is more expensive than the shoes bolted to it.
3. Bushings — condition, and whether they have already been rotated. A rotated bushing has one life left, not two.
4. Rollers and idlers — flange wear and tread wear, both sides.
5. Sprocket tooth profile. Hooked teeth mean the chain has already stretched. This is the finding that quietly doubles the bill, because a new chain on hooked sprockets destroys itself.
6. Track sag at correct tension.

Express every item as a percentage of life remaining. Never as “good” or “worn” — those words cannot be negotiated with, and negotiating is the point of measuring.

It is entirely possible to have decent grousers sitting on a chain that is finished. Shoes are the cheapest part of an undercarriage.

4. Structure and welds — where fraud hides

Everything above can be found by an honest seller and disclosed. This is the section where somebody has decided not to tell you.

Look at the welds at the boom foot, the boom mid-section, the cylinder mounting ears, the stick nose and the track frame. What you are looking for is not a crack — a crack is easy. You are looking for evidence that a crack was dealt with:

• Grinding marks where there should be original weld bead.
• Paint that does not match the age of the paint around it.
• Filler. Run a magnet over anything suspicious — it will not hold on body filler.

Check pin and bush play at every joint by working the function and watching the joint itself, not the boom tip.

Photograph anything doubtful twice: close, and in context. A close-up of a weld with no context is useless three days later when you are trying to remember where on the machine it was.

A concealed structural repair at a high-stress weld is not a negotiating item. It is a reason to walk away, or at minimum to insist on non-destructive testing before any money moves — no matter how good the rest of the machine is.

5. Hydraulics — time it, then measure the drift

This is the strongest diagnostic available to you without a pressure gauge, and almost nobody does it.

Cycle times. Warm the machine to operating temperature. Then time each function at full throttle — boom raise, boom lower, stick in, stick out, bucket curl, bucket dump, full slew both ways — and compare each against the manufacturer’s specification for that exact model.

Read the pattern, not just the numbers:

• A consistent 15–25% degradation across all functions points at pump wear. That is the expensive answer.
• Degradation on one function only points at that circuit’s valve or cylinder. That is the cheaper answer.

Then the drift test, which takes five minutes and is worth more than the previous hour. Raise the boom fully, hold the machine still, and measure rod extension loss over five minutes with a steel rule. Repeat for stick and bucket. Movement beyond specification means cylinder seal or holding-valve leakage.

Write down the actual millimetres. “It drifted a bit” is not information.

6. Engine — read it, do not just listen to it

• At idle, take the oil filler cap off and look at the crankcase pressure and vapour coming out. Heavy pulsing blowby means ring and liner wear, and it is the most expensive finding on the machine.
• Dipstick. Smell it for fuel dilution. Look at the colour for coolant.
• Coolant header tank at idle — watch for combustion bubbling.
• Leaks. Clean the area, run it twenty minutes, and look at the same point again. A cleaned engine bay tells you nothing until you have made it dirty again.

7. Hours — verify, do not transcribe

The number on the display is a claim, not a fact. Cross-check it against:

• Pedal rubber and floor plate wear
• Seat bolster collapse
• Joystick grip wear
• Paint wear at the entry step and the grab handle
• Service records and fuel consumption logs

A machine claiming 9,000 hours with 20,000-hour pedal wear is telling you something, and it is not about the pedals — it is about every other number you have been given.

Record the reading and your verification opinion separately. They are two different pieces of information, and merging them is how an inspection report becomes worthless.

The order matters more than the list

Almost everything above is known to anyone who has been around machines. What people get wrong is sequence: they fall in love with the machine, and then they inspect it.

Do the documents while you are still capable of walking away. Insist on the cold start before you have invested three hours. Measure the undercarriage before you have started imagining the machine on your site.

And write everything down as you go, in millimetres and seconds and percentages — because in four days’ time, when you are negotiating, “it seemed fine” is worth nothing and “boom drift 11 mm in five minutes” is worth a great deal.