How to Bleed Air from a KTI Hydraulic Power Unit β Official Procedure
KTI's bleed cycle is a three-stage raise/lower sequence: raise 1/3 and lower fully, raise 2/3 and lower fully, raise all the way and lower fully. Watch the fluid through the open breather cap during each raise stroke. Repeat until no air bubbles are visible. Top off the fluid level after each complete cycle.
When to Bleed the System
- New pump installation β before first use
- After any hydraulic fluid change
- After replacing or servicing any valve, hose, fitting, or cylinder
- After running the reservoir low (below half) during operation
- After installing a wireless controller or re-plumbing any line
- Whenever you notice spongy, slow, or inconsistent raise/lower behavior
Fill the reservoir to the Full line β approximately 1 inch from the top with the cylinder fully retracted β before beginning. Never start a bleed cycle with low fluid. Running the pump with insufficient fluid introduces more air and defeats the procedure.
KTI's Official Bleed Procedure β Step by Step
Perform with no load on the trailer bed.
- Remove the Breather Cap
Remove the filler/breather cap from the reservoir so you can observe the fluid during operation. Watch for air bubbles or aeration (foamy, turbulent fluid) returning to the tank. Keep the cap off for the entire procedure.
- Raise 1/3 of the Way, Then Lower Fully
Press Up and raise to approximately 1/3 of full extension. Watch the fluid β if you see vigorous bubbling or aeration, stop immediately and wait for the fluid to settle, then continue. Once at 1/3, press Down and lower completely to the seated position.
- Raise 2/3 of the Way, Then Lower Fully
Raise to approximately 2/3 extension. Watch for aeration. Stop and wait if needed. Lower completely.
- Raise Fully to End of Stroke, Then Lower Fully
Raise to full extension. Watch for aeration. When the cylinder reaches end of stroke, lower fully. Do not allow fluid level to drop below half-full at any point during these steps.
- Check and Top Off Fluid Level
With the bed fully lowered, check the reservoir level. It will have dropped as air was displaced by oil. Top off to the Full line. Replace the breather cap.
- Repeat Until No Bubbles Are Visible
Most systems clear in 1β3 complete cycles. If aeration persists after 4β5 cycles, there is likely an active air leak β a loose fitting, pinhole hose, or valve not fully seating β that is continuously introducing air. Inspect all connections before repeating.
What to Watch For
| What You See in the Reservoir | What It Means |
|---|---|
| Fluid returning smoothly, small ripple | Normal β little to no air in circuit |
| Small bubbles quickly dissipating | Minor air present β one more cycle should clear it |
| Vigorous foaming, turbulent fluid | Significant air β continue cycles, check fluid level |
| Fluid overflowing reservoir | Too-high fluid level, or large air volume. Drain slightly and continue. |
| Aeration persists after 5+ cycles | Active air leak β inspect all fittings, hoses, and cartridge valves |
