Quick note: A machine that presents several issues should not be immediately discarded. Rather it’s just part of the evaluation process regarding the quality of the machine.  Every piece of the puzzle will help determine a machine’s quality, value and potential problems. If you take your time and use a thorough approach, you can be confident you made a well-informed purchase.

I.  Power Source: Engine (gas, diesel, dual fuel) / Battery powered

          Engine powered – Start machine and look for the following:

                      1) Do you see any thick black smoke on startup?
                      2) Take cap off oil dip, do you see any light/white smoke shoot out?
                      3) Put hand over oil dip while machine is running, do you feel any pressure build up?
                      4) Do you hear knocking? Is it light, or heavy?
                      5) Check oil, is it black and old?

Any positive result from above is an indication of a weak engine or one that has bad compression. The main fixes can involve replacing the engine seals, rebuilding the engine or replacing the engine altogether.  Machines can still last quite a few hours with these issues present. However it may not be wise to pay top dollar for such a unit.

**Engine hours matter less than most people realize. If the engine passes every test AND the oil looks great, do not be overly concerned if one machines hours are higher than the next. The above tests are a much better gauge to an equipment's condition.

         Battery (electric powered machine)

                      1) Check date on batteries.
                      2) Check water level inside batteries, use a hydrometer if possible.
                      3) Check the corrosion around the electrical connections.

Batteries will typically last 4-6 years when properly maintained. All cells should be full of water and the hydrometer should test consistent within each cell.

**Batteries are typically not a huge issue on most scissor lifts, to replace them cost typically $400-600. However, the larger machines (single man lifts, electric boom lifts) require a much more expensive set of batteries. It is more important to understand the battery's condition at this point.

II.  Electrical wiring (wires inside & outside the machine, wiring harnesses)

          Look at the wires visible on the outside of the machine.            

                   1) Check wires & harnesses that are exposed to the weather.
                      2) Do they look old and stressed? Or in good overall shape?
                      3) Do they have splices or spots that have been taped?
                      4) Look at the points where wires fit into a male or female plug.
                      5) Push and pull on each individual wire, how are the connections?

          Look inside the machine.

                   1) Do the wires look weathered?
                      2) Do they show any signs of corrosion?
                      3) Are there splices or burn marks?

The overall condition of the machine's wiring is typically consistent. If a set of wires look old and weathered, most other wires will be the same as they wear and age at the same pace. Some differences may occur based on if the wires are protected from the outside elements or not. It’s important to look for good overall condition along with minimal signs of tampering (tape and splicing), and no burn marks (caused by shorts and corrosion).

III.  Control Platforms (Ground & Basket)

          Look at each control panel.

                      1) Can you see all the buttons, toggle switches and symbols clearly?
                      2) Are the joysticks firm and do they return into proper position, or are they loose and/or stick?


          If possible look inside the control panel.

                      1) Is the wiring inside in good shape?

                      2) Use the indicators from above.

The overall condition of the platform and ground controls deals with how well each button, joystick and switch function. The more expensive underlying area to evaluate is the electrical wiring inside the control boxes. If you get a chance to take a look inside, the condition should be close to perfect. It is not exposed to the elements and very rarely has evidence of corrosion. Do a quick check for tampering or splicing which would indicate somebody tried to perform a quick fix rather than a proper fix.

IV.  Drive System – Wheel Motors (Electric & Hydraulic), 4WD

One quick way to determine if you have electric or hydraulic drive motors can be the slight lag time associated with pressing the drive function and when the action takes place. With hydraulic motors, there can be a whining sound and slight pause before the machine drives. With electric motors, the action is immediate.

          Electric Drive Motors – drive the machine for 5 minutes and observe the following:

                      1) Do you notice any signs of motor oils leaking or dripping from the motor?
                      2) Do you smell anything burning?
                      3) Does one motor feel warmer than the other?

It’s best to outright replace any motor that demonstrations any of these issues.  While it may be possible to run your machine with these issues present, there is no direct indication when you have reached the final threshold. Typically a floor full of motor oil or a completely locked up motor is the outcome of that “final threshold”. As you can see, it’s best to preventively correct these issues.

          Hydraulic Motors – drive the machine around for 5 minutes, observe the following:

                       1) Look for any signs of leaks.
                       2) Listen for any sounds of grinding.

If no signs are evident, the motors are ok.

          4wd – This can be difficult to test on a machine.

Besides putting the machine up on blocks and assessing whether all four wheels turn simultaneously there isn’t an easy test. Perhaps if you are able to run the machine through subpar terrain and see how it responds can be decent solution.

The best advice here is to stay away from a machine that is known to have 4-wd issues. While the fix could simply be a quick electrical wiring issue, it could also be the internal hydraulic pump. Too many unknowns with a potential big money fix (hydraulic pump).

V.  CPU (Motherboard, “brains” of machine)

          If you can locate the CPU of the machine look for the following:

                      1) Inspect the board for signs of burnouts, electric shorts or corrosion.
                      2) Look at the wires leading directly into the CPU and look for any signs of electrical issues (mentioned above).
                      3) On machines with a covered CPU module there is nothing that can be observed directly. Run the machine

                      each function to ensure its working properly.

These signs may indicate imminent CPU failure or possibly an improper voltage input.  Replacing a motherboard is expensive. This is an important thing to check.

When running the machine’s functions, discernment may be needed if a function fails. It doesn’t necessarily point directly to a CPU issue.  Direct clarification should be sought.

VI.  Fuel Delivery System

          Fuel tank, main fuel hose line

                      1) Check to see if the fuel tank is clean and without debris.
                      2) Check to see if the main hose line coming out of the fuel tank is in good shape.
                      3) Check to see if any inline filters exist and look at their condition.

While nothing represents a huge cost, the fuel tank may have to be flushed out if too much debris exists. Be sure the hose is in good shape. Finally, the filter should be relatively clean without too much build-up. A clean fuel system gives the motor better running conditions.

          Fuel pump, Fuel filter, in-line fuel filter, fuel hose past the inline filter

                      1) Check to see the fuel pump turns on and off on startup.
                      2) Open the fuel filter and look for any type of debris (especially anything metallic).
                      3) Open the inline fuel filter and make sure it’s clear of any build-up.
                      4) Look at the fuel hose that connects directly to and throughout the engine.

Again, nothing here represents a huge cost to fix preventatively, however its overall condition needs to be evaluated. The fuel pump needs to drive the initial fuel to the motor on start-up. The wires and hose line should be in good shape. The fuel filter should be clear of any debris especially any microscopic metal that could compromise the engine. This is where a rusty fuel tank could be devastating. The fuel hose running throughout the engine needs to be a proper threaded fuel hose and not some knock-off rubber material. Any leaks or fuel escaping from this hose can spark an engine fire.


VII.  Hydraulic System

          Hydraulic Reservoir - Run the machine through its functions &observe the following:

                      1) Does it look cloudy?

                      2) Does it have air bubbles?

This will let you know if there are any foreign substances in the hydraulic system. Fuel, water and air can all find their way into the system for one reason or another. It is important to flush the system properly and refill to specifications to fix any issues. Prolonged usage with dirty hydraulic fluid can eat away at the entire hydraulic system causing multiple problems throughout.

           Look at the rotators on the machine (Boom lifts mainly).

                *BOOM lifts will have a rotator under the machine which turns the body of the machine and a rotator near the basket

                   which controls the motion of the basket left and right.

                      1) Do you notice any leaks or drips?
                      2) Do you notice any bolts missing or oblong bolt holes where the screws fit?

Any leaks or drips on the rotators (especially the rotator under the machine) are an expensive and time consuming issue. While it may be ok to deal with the drip or leak for a while, at some point it will become a must fix. Further if you notice bolts sheared off or oblong screw holes on the rotators this indicates major unwanted stress on the machine. The problem could be localized to that rotator or include the entire structural integrity of the machine. It’s simply better to pass on such a machine.

          Look at the hoses both inside and on the outside of the machine.

                      1) Are they cracked, or do you see metal showing through at the main bend/stress points of each hose?
                      2) Do you see drips or leaks at the connections/manifolds?

Hydraulic hoses are one issue to never take a wait and see approach. If they don’t look relatively new and stable it’s always a better idea to replace them beforehand. Hydraulic leaks will cause difficult to clean situations to the surrounding buildings & grounds. Look for the constantly moving and bending portions of the visible hydraulic hoses as they will wear quicker than anywhere else. The inside hoses should look relatively clean as they are protected from the elements. Look for any drips or leaks at the manifolds as that will indicate an O-ring needs to be replaced.

          Look at the cylinders, especially the main life cylinder

                      1) Do you see any evidence of hydraulic leaks or drips?
                      2) Do you see any minor scraps or cuts in the cylinder arm?

Depending on the cylinder in question, any repairs could be minor to major. It’s essential any cylinder leak either gets repacked or replaced.

VIII.  Structural Steel – (Machine’s frame, Basket, Wheels mounts)

          Give the machine a quick eyeball test

                      1) Does it look twisted or out of shape?
                      2) Run the machine through its functions again
                      3) Do you hear any strong whining or feel any stress bumping during any of the functions?

This can indicate something is structurally off, or it can simply be a product of worn out slide pads, or lack of lubrication. Discernment is needed.

          Look at the wheels on the machine.

                      1) Do they bend in towards the machine slightly?

This can be an indication of stress due to the constant tying down of the unit for transportation. Or it can be a sign that the king-pins holding the wheels in place are warped. These are safety issues that have to be addressed.

          Look at the basket or cage of the machine.

                      1) Is it structurally intact?
                      2) Are there substantial cuts or bends on the rails?


                      1) Does the deck slide in and out easily?
                      2) Are all the pins present which keep the fold down rails in place?
                      3) Are there any substantial cuts or bends on the railings?

          FOR BOOM LIFTS

                     1) Do all the latches close properly?
                     2) Are there safe tie-down points for a harness?
                     3) Are there any cuts or bends on the railings which keep you safe?
                     4) What is the condition of the wire steel on which you stand?
                     5) Is the foot pedal intact and operational?

The basket or platform of the machine needs to be structurally intact. This is for your own safety. Consider major issues within this area a must-fix.

IX.  Tires (Electric, Rough Terrain / Foam-filled, Air-filled)

         Electric type lifts (indoor tires)

                      1) Check for any nails or screws in the rubber.
                      2) Check for any big chunks missing around the rims and on the wheel surface itself.
                      3) Are the rims structural intact or are they dented or punctured?
                      4) Do the rims wobble when the machine is in motion?

As long as the rubber on the tire is intact, removing any nails or screws is never a huge issue. At the point where chunks of rubber are coming off, it may be time to replace the tire. Be sure the rim is structurally sound and the wheel doesn’t wobble when in motion. This indicates more than a simple tire change is needed. Most likely it’s a pin issue or the rim itself has been bent. This is a safety issue that needs to be addressed.

          Rough terrain lifts (outdoor tires), Air-filled

                      1) Check for any nails or screws in the rubber.
                      2) Check for any deep cuts or gouges especially on the tire wall.
                      3) Check for plugs in the tire.
                      4) Check for proper treading.
                      5) Check for any rim damage, including dents that could affect the tires ability to maintain air and proper
                      6) Checks to make sure all four tires are the same and hold proper air pressure.

This is mostly self-explanatory, however be sure to assess whether a tire may simply need replacing or whether a new rim and tire is needed. Those are two entirely different costs.

          Rough Terrain lifts (outdoor tires), foam-filled

                      1) Check for any deep cuts or gouges that expose the underlying tire foam.
                      2) Check for proper treading on the tire.
                      3) Check for possible rim damage on each wheel.

Any tire that has its foam exposed needs to be replaced. At the point where the foam is exposed, the tire will deteriorate quickly. Typically foam-filled tires will last 8 – 10 years or 4000-5000 hours before replacements need to be considered.

Anyone can pick up this list and assert there are areas which were skipped. Please realize it’s difficult to assess every possible facet of each machine type. There are literally hundreds if not thousands of combinations. This broad based checklist will give you a decent indication as to the machines over all condition and you can be much more confident about your purchase.

Advanced Equipment Evaluations

Milton Enterprise, LLC

​​​​​​​49 N Union St.

Pawtucket, RI 02860

401-714-7754 (phone)

401-229-2041 (fax) 

Construction Equipment Sales & Rentals