Equipment World Magazine - June 2002
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How to inspect a used compact excavator
By Tom Jackson
They look and work a lot like their bigger brothers, but compact excavators present a different set of variables when you are evaluating a used one for purchase.
The compacts are used a lot by specialty trades — electricians, plumbers, swimming pool contractors and such. This means they may only see as little as 500 hours of work a year. Compact excavators from rental fleets log more hours per year, but in general, these are fairly low-hour machines for their age.
We talked with Gary Beal, vice president, used equipment division, and Jody Lemoine, service manager, at Head & Engquist, an equipment dealer in Baton Rouge, Louisiana, about how to evaluate a used compact excavator. They chose a Komatsu PC27R compact excavator for our walk-around inspection.
Know what features you want going in
Compact excavators debuted in North America in the mid-1980s and today's machines include features that weren't always part of older models. So you need to know ahead of time what features you can and can't live without.
"Joysticks are more desirable than lever-activated controls," says Beal. "And blades were not always standard equipment. You also want to look for a pivoting boom, so you can get up close to buildings, and auxiliary plumbing, so you can put on attachments." Zero tail swing has also become important to contractors wanting to work in tight spaces.
Buckets and booms tell tales
"Excavators are not always applied as a digging machine," says Lemoine. "Contractors drive pilings with them, or they set pipe with them. So, you have to look at the condition of the bucket. Make sure nothing is bent underneath it where they were driving pilings, hammering rocks or driving posts."
Next in line are the bucket-cylinder linkage and the pins and bushings. "Always check for slack in the pivot points," says Lemoine. "I've changed so many of these it's unbelievable, and its all due to lack of maintenance."
Start the machine and move the bucket, dipper and boom. "You'll see the pins move, or see that the cylinder is moving, but the stick or bucket is not. That's because it's taking up the slack in the pin and bushing," says Lemoine.
Another crucial pivot point is the connection between the boom and the body of the excavator. "If you get too much wear in the boom pivot point, it can be very expensive because you get into the casting if it gets bad enough," says Beal.
Oil leaking out means dirt creeping in
This is also a good time to inspect the hydraulic cylinders and tubes. Ideally, the chrome surface of the cylinder should show no scratches, pitting or oil leakage. "If oil is getting out, that means dirt is getting back in, and that's a good indication you have a contaminated hydraulic system," says Beal.
Also make sure the cylinder barrels are not damaged or dented. "The tolerances between the tube and the cylinder are so close that if you have a dent in the tube, running the cylinder in and out of it is liable to create a lot of wear and introduce metal into your hydraulic system," says Lemoine.
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Be wary of body work and welds
While you're still on the front end of the machine, look for any cracks in the metal or non-factory welds. These would indicate that the machine has suffered some abuse or been pushed beyond its capacity.
It's also a good idea to eyeball or put a straight edge on the boom and dipper stick to make sure they haven't been bent or twisted, says Beal.
Keep a sharp eye out for excessive sheet metal repair. While a few scrapes and dings can be expected on a used machine, significant patches of Bondo may indicate a history of abuse or neglect. A large, thin layer of Bondo is probably covering up pitting.
Rubber tracks and undercarriage
The rubber track on most compact excavators is altogether a different beast from the steel tracks on bigger machines. It's easy on grass and driveways and the machine's undercarriage too. "You don't see near the wear with rubber tracks that you do with steel," says Lemoine.
As a result you won't see much wear on the sprocket gear or the rollers. What wears out is the rubber track itself. Look for rips and tears in the rubber and examine the edges for signs of fraying. You should also look at the height of the rubber grouser pads and determine how close those are to spec. "It's just like a tire where there are measurements for tread depth," says Lemoine.
The working life of a rubber track varies greatly depending on use and soil conditions. On average they should last about 2,000 hours. But you can cut that in half in rocky or abrasive conditions, or almost double it in more forgiving environments.
While you're inspecting the track and undercarriage, check the oil level and cleanliness in the final drives. "It's often overlooked, and there is usually less than a quart of oil in one of these final drive assemblies," says Lemoine. "But if it's low, or has water or foreign matter in it, that could spell trouble."
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Operational checks
With the engine warmed up and running, tilt the machine up on one track and rotate the track that's in the air. Note how many times it turns in 30 or 60 seconds and then compare that to the other track.
"An excavator's tracks are a built-in hydraulic flow meter," says Lemoine. "If the two are not giving you the same rpms, then you may have a problem." Another way to check this, adds Beal, is to drive it for 30 feet on level ground. "If it runs straight, you know both travel motors are performing equally well," he says.
Also, check the performance of the swing gear and swing gear bearing. It should rotate the superstructure with little or no deflection and stop and start accurately and smoothly with no lurching or slop. On compact excavators, the swing gear and its bearing should last the life of the machine, so any play or sloppiness here is cause for concern.
Under the hood
Pop up the hood and check the blow-by tube for signs of smoke. You can also pull the dipstick and look for smoke through that opening as well," says Beal. Excessive smoke usually means you're going to need to replace the piston rings and possibly overhaul the engine soon.
Inspect the air cleaner and all the clamps and ducts. "It only takes a tablespoon of dirt to destroy an engine," says Lemoine. Look downstream for dust or dirt accumulation as well. Also check the fan to make sure the belts are tight and inspect the radiator to make sure it is clean. Compromised or neglected cooling and air systems can cause engines to overheat and shorten their lives.
Also run through the basics. Check for clean radiator fluid and engine oil. Inspect the battery for corrosion, and look around the engine compartment for obvious signs of leakage or neglect.
If you shop around for anything larger than a garden tractor, sooner or later you will hear the term "grey market" tractor. A grey market tractor is simply a used tractor, usually a compact diesel, imported from another country, usually Japan. Demand for compact diesel tractors is quite high and grey market tractors are becoming a popular option for an increasing number of tractor buyers. However, there are both advantages and disadvantages to purchasing a grey market tractor. 
