How to inspect a used compact excavator
Man the controls of these small power horses to get a good feel for how a used unit will perform.
| March 01, 2012
A good used compact excavator – also called a mini excavator – can give you the maneuverability and versatility you may be missing with your larger machines.
In order to make a solid buying decision though, you’ll need to give a used compact excavator a thorough inspection. We asked Mike Whittaker, senior shop technician with Gregory Poole Equipment, Raleigh, North Carolina, to give us a roadmap for inspecting these machines. He chose as his inspection machine a Caterpillar 303 CR with 3,000 hours.All good inspections start with a walk around, which will highlight any obvious problems, some of which may stop you from exploring further.
Looking for leaks at this point is especially critical, Whittaker says. “Check for leaks in the hoses and cylinders, and especially under the machine,” Whittaker says. “You don’t want to start the machine with a major leak or a torn out bottom.”
Then examine the frame, ROPS, boom, stick and blade welds for any cracks. “On welds that have started to crack, you can see a line of rust where the bare metal is exposed,” Whittaker says. Look at the steps and grab irons, making sure the steps aren’t bent and they’re secure. And note any missing safety decals. Does the machine need to be repainted?
Open up each service compartment, noting whether the latches work. Make sure the fuel tank cap and strainer are in place and working. Judge whether the battery is secure or if there’s evidence of corrosion on the terminals.
Look for oil seepage in the boom and stick cylinders, or if there are damaged hydraulic lines. Are all brackets in place?
Start the machine and get it up to operating temperature. Whittaker then runs it through a series of operational checks:
• Do several simulated digging cycles with the boom, stick and bucket. Then swing the boom left and right, extending the stick and opening and closing the bucket. Look for any looseness in the pins and bushings or coupler.
• Operate the blade up and down. Raise the front of the machine with the blade.
• Swing the upper body to the left and right, again checking for hesitations. Brake during each rotation, and note the response.
• Run the machine in forward and in reverse and turn left and right with the tracks. Are the controls operating smoothly? Does the backup alarm work?
• Moving the boom to one side and using the bucket as an anchoring point, lift the machine and run the elevated track, checking for any cuts, missing chunks or dry rot in the rubber. Make sure it rotates freely. Repeat on the other side.
While you’re in the seat
During your operational checks, listen for unusual engine noises. Also note whether gauges, lights and the horn work properly. Are the mirrors intact? Make sure the seat is in good condition, fully adjusts, the seat belt is operational and the safety and operator’s manuals are in place. If your machine has an enclosed cab, check the door latches, note any cracks in the glass, and whether the window wipers and air conditioning work.
Step out of the cab and open the engine compartment to check for blow-by. “I’ll pull out the dipstick and feel for pressure,” Whittaker says. “Some will be normal, but if the pressure is excessive you probably have some power issues.”
Now that you’ve put the machine through its paces, do another walk around, this time delving deeper into the service compartments. “I look at the general cleanliness,” Whittaker says, “and whether the engine compartment is full of dirt or the radiator has debris.”
In the engine compartment, check for oil leaks in the valve covers, seals and oil pan. Examine all fluid levels – engine and hydraulic oil, plus coolant levels. Note the oil condition – if it’s black, then it probably has been awhile since the oil was changed. Check for water in the engine oil. Note the color of the antifreeze. Make sure all filters show current dates and are in good condition.
Note the color of the antifreeze. Make sure the water pump, fan and hoses are working properly. The fuel tank cap and strainer need to be in place and working. Check to see if the battery is secure, and there’s no evidence of corrosion on the terminals.
If your machine has a steel undercarriage, look at the pins and bushings, track shoes, idlers, carrier rollers and links. Determine the percentage of wear remaining.
Finally, ask for maintenance records and an oil sample history. If this is a machine you’re serious about, get an oil sample tested and compare it to past oil samples.
Check out the checklist below for a full list of what to look for.
Used Compact Excavator Checklist
Engine make/model:Number of hours:
il sample results:Service records:
Walk around condition check
Radiator grill and shroud
Service compartment doors, hardwareEngine enclosureFuel tank
Main frame welds
Steps and grab irons
Compression in radiator
Water in oil
Fluid levels OK?
Oil filter condition
Pumps and valves
Rubber or steel?
• Pins and bushings
• Track shoes
• Carrier rollers
• Percentage of life remaining?
Pins and bushings
Pins and bushings
Safety decals in place and legible?
Floor boards, mats
Safety and operators manuals present?
List any attachments and their condition:
Comments of previous owner or seller Detail any recent repairs and rebuilds and who did them Condition of maintenance records – available electronically? Note any repairs and estimated costs