How Do I Bleed Air from the Hydraulic System and Top Off the Fluid on My BendPak, Atlas, or Triumph 2-Post Car Lift?

Air trapped in the hydraulic system is one of the most common reasons a 2-post car lift (two-post hydraulic vehicle lift) operates poorly—especially on popular brands like BendPak, Atlas, and Triumph. Symptoms include:

• Spongy or bouncy lifting/lowering

• Uneven rise (one side higher than the other)

• Slow operation or hesitation

• Jerky movement

• Excessive pump noise (cavitation)

• Lift fails to reach full height

Air enters the system primarily through low fluid levels (pump sucks air), minor leaks, improper initial bleeding after installation, temperature changes, or after component replacement (cylinders, hoses, power unit). Fortunately, bleeding air and topping off the fluid is a straightforward DIY procedure that most owners can perform with basic tools and care. This comprehensive guide provides detailed, safe, step-by-step instructions tailored to BendPak, Atlas, and Triumph models (which share similar single-cylinder-per-column designs and power unit layouts), while also explaining best practices for fluid selection and prevention.

Important Safety Notes

• Always work with the lift fully lowered and no vehicle on it.

• Disconnect power to the unit before close inspection.

• Wear safety glasses and gloves—hydraulic fluid under pressure can cause injury.

• Use only the manufacturer-recommended fluid (typically ISO 32 or 46 non-detergent hydraulic oil or Dexron III/Mercon ATF—check your manual). Never mix types.

• If you suspect a major leak or cylinder seal failure, stop and call a professional.

Tools & Supplies Needed

• Correct hydraulic fluid (5–10 quarts, depending on model)

• Clean funnel with long flexible spout

• Rags/paper towels

• Catch pan or drip tray

• Allen wrench or hex key (usually 5/32"–3/16" for bleeder screws)

• Flashlight

• Maintenance logbook

Step-by-Step: Topping Off Hydraulic Fluid (First Step – Do This First!)

Low fluid is the #1 cause of air ingestion. Always check and top off before bleeding.

1. Lower the lift completely — Ensure carriages are at the bottom and settled.

2. Locate the power unit reservoir — Typically mounted on the side or rear of one column (BendPak/Atlas often on passenger side; Triumph similar).

   • Most have a sight glass (plastic window) or dipstick/cap.

   
   

3. Check fluid level

   • Sight glass: Fluid should be visible in the middle or between min/max lines.

   • Dipstick: Wipe clean, reinsert, remove—level between low/full marks.

   
   

4. Top off slowly

   • Use funnel to add small amounts of the correct fluid.

   • Wait 30–60 seconds between additions for settling.

   • Stop when level reaches the full mark (overfilling causes foaming/air).

   
   

5. Inspect for leaks while topping—check hoses, fittings, cylinders, power unit seals.

After topping off, proceed to bleeding if symptoms persist.

Step-by-Step: Bleeding Air from the Hydraulic System

The goal is to force air bubbles out through the highest point in each cylinder (bleeder screws).

Most Common Method (Used on BendPak XPR Series, Atlas, Triumph, Many Others)

1. Prepare the lift

   • Ensure fluid is topped to full (as above).

   • Raise the lift unloaded to about 12–24 inches off the ground (first or second safety lock position).

   • This puts the cylinders in mid-stroke where air tends to collect at the top.

   
   

2. Locate the bleeder screws

   • On each column, near the top of the hydraulic cylinder (usually on the cylinder cap or side).

   • Small Allen/hex screw (5/32"–1/4" size).

   • Have rags/pan ready—fluid will escape.

   
   

3. Bleed each cylinder

   • Start with the higher side if uneven (or left column first).

   • Slightly loosen the bleeder screw (1/4–1/2 turn counterclockwise)—do not remove completely.

   • Fluid + air bubbles will spurt out (hold rag over it).

   • Let it flow until only clean, bubble-free fluid comes out steadily (may take 10–30 seconds).

   • Tighten bleeder screw snugly (do not overtighten—can strip).

   • Repeat on the other cylinder.

   
   

4. Cycle the lift

   • Fully raise the lift (unloaded) to top height.

   • Hold for 10–20 seconds.

   • Slowly lower all the way down.

   • Repeat this full up/down cycle 3–5 times to purge remaining air from hoses and power unit.

   • Listen for smoother operation; watch for even travel.

   
   

5. Recheck & top off again

   • After cycling, fluid level will drop as air is displaced.

   • Top off reservoir again to full.

   • Repeat bleed/cycle process if sponginess remains (may take 2–3 rounds).

   
   

Alternative Method (If Bleeder Screws Are Hard to Reach)

• Raise lift to full height.

• Cycle up/down repeatedly (10+ times) while monitoring fluid level.

• This method is slower but works on some models without accessible bleeders.

Troubleshooting Tips

• Persistent air after multiple attempts → check for leaks (hose cracks, loose fittings, bad cylinder seals).

• One side still spongy → focus bleeding on that cylinder; may indicate localized air pocket.

• Pump very noisy → low fluid or failing pump (professional needed).

Fluid Change Interval & Best Practices

• Top off as needed (monthly check).

• Full fluid change every 1–2 years or if fluid is milky (water), dark/burnt, or contaminated.

• Always use fresh, sealed containers of the exact spec fluid.

• Keep reservoir cap/breather clean to prevent contamination.

Why Choose Eounice Car Lifts for Reliable Hydraulic Performance

While BendPak, Atlas, and Triumph are popular choices, many owners experience frequent air issues due to design tolerances or seal quality. Eounice car lifts offer a superior alternative with precision-engineered hydraulic systems, high-quality cylinders, robust seals, and minimal air entrapment. Their models are known for smooth, consistent operation with fewer bleeding cycles required after installation or fluid service—ideal for both home garages and professional shops.

Eounice emphasizes durability and ease of maintenance, reducing common hydraulic frustrations.

For model-specific bleeding tips, fluid recommendations, or to learn more about Eounice 2-post lifts with dependable hydraulics, contact their support team at marketing@eounice.com—they provide outstanding guidance!

Final Checklist & Safety Reminder

After bleeding and topping off:

• Perform 5+ full unloaded cycles

• Confirm smooth, even, quiet operation

• No sponginess or bouncing

• Fluid at proper level

• Log the date and fluid added

Bleeding air and maintaining proper fluid levels is a routine task that restores your BendPak, Atlas, or Triumph 2-post lift to peak performance. Do it correctly, use the right fluid, and address leaks promptly. With consistent care—or switching to a more reliable system like Eounice—your lift will deliver safe, dependable service for decades.

Lift smart and stay safe! 🚗🔧