Two Post Lift Wont Lift Troubleshooting

When a shop calls us about two post lift wont lift troubleshooting, the story is usually the same: the tech pulls a car in, hits the up button, the power unit fires right up, and the carriages just sit there. Nothing moves, or the lift crawls up six inches and stalls. We’re Auto Lift Services, based in Ames, Iowa, and between installs, annual inspections, and parts orders we walk somebody through this exact problem most weeks of the year. The good news is that a lift that runs but won’t raise a load is almost always a fluid, air, valve, or overload issue — not a dead lift. Here’s how we work through it in the order that finds the cause fastest, and what we’d tell you to check before you pay for a service call.

Start With What the Motor Is Actually Telling You

The first fork in the road is whether the motor runs. If you press up and hear nothing at all — no hum, no click — you’re chasing power, not hydraulics, and our two post lift electrical troubleshooting walkthrough is the better starting point. Check the breaker, the disconnect, the up button contacts, and whether somebody swapped a 240V unit onto a circuit that lost a leg. Single-phase power units that lose one leg often make a low growl and cook the start winding, so don’t keep jabbing the button.

If the motor runs normally and nothing rises, you’ve narrowed it to fluid delivery. That’s the most common scenario in two post lift wont lift troubleshooting calls, and it usually means the pump is spinning but not moving oil to the cylinders — low reservoir, an open lowering valve, a stuck check, or air trapped in the system. Listen carefully at the power unit while a helper holds the up button. A pump that’s cavitating makes a higher, whinier note than one under load. A pump moving oil against a closed valve will bog down and the motor note will drop. Those two sounds tell you a lot before you ever pick up a wrench, and they’re free to gather. Note whether the lift behaves differently empty versus loaded, too — that distinction matters in the next step.

Fluid Level: The Cause in Roughly Half of These Calls

Pull the fill cap with the lift all the way down and look. Most two post power units want the reservoir filled to within an inch or two of the top with the carriages fully lowered, using AW-32 or ATF depending on the manufacturer’s plate. We have found reservoirs in central Iowa shops with barely a cup of oil in them, and the owner had no idea because the lift still worked — badly — for months.

Low fluid does two things. It starves the pump so the lift stops partway up, and it lets the pickup suck air, which is why a low lift often rises in jerky stages or drifts back down overnight. Top it off with the correct fluid, then cycle the lift up and down through its full travel four or five times with no vehicle on it to purge the air. Watch for the level to drop again after that purge, and watch the floor. If fluid is disappearing, you have a leak — hose fitting, cylinder rod seal, or the power unit base — and topping off is a band-aid. During two post lift wont lift troubleshooting, we always follow low fluid back to its cause rather than just refilling. A cylinder that has been running on aerated oil long enough will eventually score, and then you’re buying a cylinder instead of a seal kit. Our broader two post lift hydraulic troubleshooting guide covers leak isolation in more detail.

The Lowering Valve Nobody Suspects

Here’s the one that fools experienced techs. If the manual lowering valve isn’t sealing, the pump pushes oil straight back to the tank and the carriages never move — or they inch up and immediately settle. The valve can be held open by a bent release handle, a dirt particle on the seat, a broken return spring, or a solenoid on electric-release units that never de-energizes because the down circuit is stuck closed.

Test it by having someone hold up while you watch the valve. Tap the handle gently through its travel. If the lift suddenly starts rising when the handle reaches a certain spot, the valve isn’t returning to seat. On air-release units, disconnect shop air from the lift entirely and try again; a leaking air line or a stuck air cylinder will hold that valve cracked open all day. We’ve fixed more than one lift by pulling the valve cartridge, flushing it in clean solvent, and reinstalling it — no parts needed. Debris is common in lifts that went years without a fluid change. When the cartridge itself is worn, it’s an inexpensive part on Rotary and Challenger power units and we stock the common ones. This check takes five minutes and belongs early in any two post lift wont lift troubleshooting sequence because the fix is often free.

Weak Lift Under Load: Pump, Relief, or Overload

A different symptom: the lift raises fine empty but stalls with a vehicle on the arms. That points at pressure, not flow. The internal relief valve may be set low or bypassing, the pump gears may be worn, or the lift may genuinely be overloaded. We get called for “weak lift” and find a one-ton dually on a 10,000 lb asymmetric lift, or a diesel pickup loaded with tools and a service body sitting on a lift rated well below it.

Check the capacity plate first. Then check how the vehicle is loaded on the arms — a truck set too far forward on an asymmetric lift puts most of its weight on two arms and can make a healthy lift look tired. If capacity and loading are correct, the power unit is the suspect. Worn pump gears bleed pressure internally and get worse when the oil is hot, which is why some lifts work fine first thing in the morning and quit by mid-afternoon. A relief valve that’s drifted can sometimes be reset, but on a unit with years on it we generally recommend replacing the power unit rather than chasing it. Our general two post lift troubleshooting notes cover how we decide between rebuild and replace.

One Carriage Moves and the Other Doesn’t

On a two post lift, both carriages are tied together by equalizer cables, and on most designs a single cylinder drives one side while the cables carry the other. So when one side climbs and the other lags or refuses, you are not looking at a hydraulic problem at all — you’re looking at cables, sheaves, or a hung safety lock.

Lower the lift fully and inspect both cables end to end. Look for slack, fraying near the sheave, a broken strand at the anchor, or a sheave that has seized and flat-spotted the cable. Check the safety latches on both columns: if a latch on one side didn’t fully release, that carriage will bind and the other will try to go it alone, which is how cables get stretched and columns get twisted. Debris in the column channel and dry slide blocks cause the same hang. We clean, lubricate, and re-tension cables on nearly every annual inspection we perform, and it’s the single cheapest thing an owner can do to avoid this failure. Never keep pressing up when one side is stuck — you can snap a cable and drop a vehicle. This category of two post lift wont lift troubleshooting is where we draw a hard safety line and tell people to stop and call.

Air in the System and How to Purge It Properly

Air is the invisible culprit behind a lot of “my lift won’t lift right” complaints. A lift that shudders, rises in steps, feels spongy, or settles an inch after you set the locks almost always has air in the cylinder or lines. It gets in through a low reservoir, a loose suction hose clamp inside the power unit, a bad cylinder rod seal drawing air on the return stroke, or simply from a recent install or repair that never got cycled out.

To purge, make sure the reservoir is full, then run the lift to full height and back down five or six times with no load. On many units you can crack the top cylinder fitting slightly at full extension to bleed trapped air — wear eye protection and expect a squirt of oil. Recheck fluid level afterward, because purging drops it. If the sponginess comes back within a few days, air is being drawn in somewhere and you need to find that entry point rather than re-bleeding forever. Loose suction line clamps inside the reservoir are the sneakiest offender we find. For symptom-by-symptom sorting, our two post lift wont raise troubleshooting article breaks these apart further.

When to Stop and Call Us

We’re genuinely happy when a shop fixes its own lift over the phone — that’s a good day for everybody. But there are places to stop. If a vehicle is in the air and the lift won’t move in either direction, don’t improvise. If you find a frayed or broken equalizer cable, a bent column, cracked anchor concrete, or a carriage that dropped onto a safety latch, the lift is out of service until somebody qualified looks at it. Those are not DIY items.

We cover Iowa and the surrounding region out of Ames, and we stock parts for Rotary, Challenger, BendPak, and Atlas equipment along with power units, seal kits, and cable sets for older lifts other suppliers have given up on. If you’ve worked through this two post lift wont lift troubleshooting list and you’re still stuck, call 800-674-9302 with your lift’s brand, model, and serial number off the column tag and we’ll tell you honestly whether it’s a part we can ship you today or a service call. We’d rather sell you a fifteen-dollar valve cartridge that solves it than a lift you don’t need — and we’ve done exactly that plenty of times. If the lift is genuinely at the end of its life, we’ll say that too, and we’ll quote a replacement with installation and anchor inspection included.