Before You Lift a Used Truck Crane, Check These Four Spots

November 14th, Nansha inspection yard. A 2015 25-ton truck crane, XCMG. The customer, Chidi, called in on video from Nigeria — on the other side of the screen, saying he wanted this machine and asking me to go over it carefully for him.

During the three pandemic years he couldn't travel, so it was all me carrying a phone around the yard. This September he finally made it to Guangzhou, put his hands on two machines himself, and sent me next year's purchase plan as soon as he got home. This crane is the third unit in that plan.

Truck cranes are the deepest water in used equipment. An eight-year-old 25-ton unit goes for RMB 280,000 to 350,000, and the whole spread lives in four places: the boom, the slewing bearing, the outriggers, and the upper engine.

I spent three hours on it, nine till noon, skipping lunch. Here's the method — follow it when you inspect your own.

The seller was a dealer from Foshan, with the crane parked at a lot in Dongguan. He thumped his chest and swore the machine was original condition, original paint. I smiled and said nothing. Fifteen years in this trade — condition isn't something you hear, it's something you feel out spot by spot.

Cycle the Boom Three Full Times First

Fully extended, the boom is 33 meters. No load, run it all the way out and back in, three times straight, listening and watching for smooth movement.

This crane caught with a clunk when retracting into the second section. I had the operator hold it mid-air and got down to look: the second-stage sliders had worn unevenly, the nylon pads thick on one side, thin on the other — 4 mm of difference.

Sliders are cheap, RMB 800 a set. But uneven wear means the boom took side loads — likely years of side-pulling and dragging loads. I ran a wire along the boom sections to check straightness: the second section was bent 2 mm. Fixable, but the price comes down.

Some sellers spray fresh paint on the boom. The fresher the paint, the more careful you should be. Paint hides rust, but it can't hide a bend — one wire check and the truth shows.

Slewing Bearing: Play You Can Feel

Set the outriggers, boom fully extended and flat, lift a 1.5-ton test weight, slew left and right, then stop hard.

Stand by the turntable with a hand on it and feel for play. Normal is under 1 mm — nothing you can feel. This crane gave me clear looseness when it swung; the feeler gauge read 2.5 mm.

A loose slewing bearing has two causes: worn raceways, or bolts that loosened and were re-torqued. Replacing the bearing runs RMB 45,000 with parts and labor. We negotiated this crane as a machine with bearing risk and took RMB 28,000 off.

A folk method Lao Li taught me: crouch and watch the bearing's outer ring while slewing. A raceway starved of grease shows a ring of dark dry-wear marks. This crane had the marks, but shallow — still usable.

Outrigger Cylinders: Watch for Leaks

Extend all four outriggers fully, lift the machine clear, and hold pressure for half an hour.

Write down the height of each leg, then measure again after thirty minutes. A drop over 5 mm means internal leakage. This crane's right-rear leg sank 11 mm, and there's a scratch on the piston rod — the seal will leak sooner or later.

Replacing an outrigger cylinder: RMB 3,200 aftermarket, 8,000 genuine. I wrote it clearly in the report and let the customer choose. The scratch isn't deep, so this time I recommended the aftermarket cylinder plus new seals — RMB 1,600 all in.

Plenty of inspectors cut corners on the hold test — extend the legs, glance, retract. Half an hour is the floor; I time it on every inspection. Seepage doesn't show in the first ten minutes. It shows after twenty.

Listen to the Upper Engine Separately

Many people only check the carrier engine and forget there's a second one up top. This crane has its own diesel on the upper structure — that one does all the lifting; the carrier engine just drives the road.

Cold start, watch the smoke. Blue smoke burns oil, white smoke means water, black smoke means poor combustion. This one puffed blue for ten seconds on a cold start — aged valve stem seals, a small fault, RMB 800 to fix.

Then listen at idle. An upper engine with a rough idle usually has dirty fuel lines; when lifting, the revs surge and the boom jerks in fits. Machines like that are dangerous to work with.

One more often-missed item: hydraulic oil. Pop the tank cap and look. Milky oil means water got in, water means a seal problem, and then the whole hydraulic system needs checking. This crane's oil was fine — golden and clear.

How to Spot a Crash Machine

A crane that has rolled over can't hide its body filler. Check three spots: the A-pillar weld spots in the cab — factory welds are neat, rewelds are messy; the mating face between turntable and chassis — look for respray; the pin bores at the boom root — cracks that were welded show grinding marks at the edges.

Two years ago in Foshan I nearly bought a 50-ton unit — pretty paint, RMB 40,000 under market. Lao Li ran a magnet around it and it wouldn't stick to the cab roof: fiberglass repair. That crane had rolled. We walked away.

This crane's report came to twenty-six pages, 110 photos, nine video clips. Sliders, bearing play, the outrigger scratch, the blue smoke — all four faults on page one. Repairs total RMB 7,200; we talked the price down RMB 34,000. Chidi read the report and sent back one line: "This is why I buy from you."

With inspections, slow is fast. Three hours checking one machine is far cheaper than three days fixing one.