How to Bleed Air and Add Fluid to Your Hydraulic Floor Jack for Optimal Performance
- Muddy Ruttzz
- Oct 24, 2025
- 6 min read
Updated: 6 days ago
Why Your Hydraulic Jack Needs Bleeding
A hydraulic floor jack is an essential tool for any home mechanic, but over time, or even right out of the box, air can get trapped inside the system. When this happens, your jack won't perform correctly—it might not lift a load efficiently, or it may slowly drift down after being pumped up.
There are a few key reasons why you might need to perform a procedure to bleed hydraulic floor jack air:
Initial Setup: You may have just purchased a new jack, and the oil level is slightly low, or a small amount of air has settled during shipping.
Oil Change/Refill: If you've changed the oil due to contamination or simply topping it off, you must bleed the system to ensure there are no air pockets introduced during the process.
Performance Issues: If you notice your jack isn't working smoothly or goes up and then slightly comes down, air trapped in the hydraulic fluid is the most common cause.
This process is straightforward and can be applied to most jacks, whether they are thirty years old like the one in my video or a brand-new model.
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Essential Tools for Jack Maintenance
Hey there! Before you dive into the process, just a heads-up to grab the right stuff. Using the wrong fluid is a classic blunder that could mess up the seals and pistons inside your jack. So, let’s avoid that, shall we?
Dedicated Hydraulic Jack Oil: Do not use any other type of oil. Hydraulic jack oil is specifically formulated for this purpose.
Clean Rags: To manage any potential oil spills.
Small Funnel or Syringe: The filler hole on a floor jack is typically very small. I found that standard funnels often don't work, so I use a dedicated syringe (like one for bleeding bicycle brakes) to accurately add the oil without making a mess. Tip: If you use a syringe, keep it only for jack oil to prevent cross-contamination with brake fluid.
Owner's Manual (Recommended): The procedure is similar for most jacks, but it's always best to check the manufacturer's specific instructions, especially for newer models.
Step-by-Step: How to Bleed a Floor Jack and Top Off Fluid
Performing a full bleed and oil top-off is a fast and easy maintenance task. Safety Note: Always work on a surface that can be easily cleaned in case of oil leak.
1. Prepare the Jack and Relieve Pressure
The first step is crucial: you must relieve all pressure from the jack before attempting to access the filler plug.
Open the Release Valve: Fully open the release valve gear (turn it counter-clockwise) so the ram is fully lowered. When you pump the jack, the ram should not rise.
Locate the Filler Plug: The filler plug is typically a small rubber or metal cap located on the body of the jack near the oil reservoir.
Loosen the Plug (The First Air Release): Use a rag and slightly loosen the filler plug. You may immediately see and hear air bubbles coming out as the pressure is released. This is a good sign—it means the system is breathing.
2. Purge Trapped Air Bubbles
With the release valve open and the filler plug removed, you can now cycle the jack to force any remaining air out of the system
•Rapidly Pump the Handle: Pump the jack's handle rapidly several times (5 to 10 pumps) to push the air bubbles out through the filler hole.
3. Check and Top Off the Hydraulic Oil
After purging the air, you should check the oil level. In many older jacks, the oil can be so clear that it's difficult to see.
Add Fluid Slowly: Use your syringe or small funnel to add a small amount of hydraulic jack oil. The reservoir is considered full when the oil level is just below the edge of the filler hole, and it may start to overflow slightly.
Replace the Filler Plug: Once the oil is topped off and all air appears to be purged, carefully replace the filler plug and tighten it down to seal the reservoir.
4. Test for Optimal Performance
The final step is to verify that the bleeding process worked and that your jack is operating optimally.
Close the Release Valve: Tighten the release valve gear (clockwise).
Pump the Jack Up: Use the handle to pump the jack up. A properly bled jack should lift the ram consistently with every single pump, rising by roughly the same amount each time.
If your jack is working smoothly, you're all set! Enjoy your fully functioning hydraulic floor jack.
Common Floor Jack Mistakes To Avoid
Never use a floor jack that slowly descends and can't hold pressure.
Check your jack to make sure no parts (bolts, nuts) missing, broken or bent.
Use double locking floor jacks! Never rely on the jack to hold the load while you work on a vehicle.
Watch the Tutorial: How to Fill and Bleed a Hydraulic Floor Jack
This article is a companion piece to my video, "How To Fill And Bleed A Hydraulic Floor Jack (Purge Air)." For a visual guide, be sure to check out the video on my Muddy Ruttzz YouTube Channel! You can also find more of my DIY and bike-related content on my blog at MuddyRuttzz.com.
About Muddy Ruttzz & The Back Story
Borrowed a floor jack from a buddy who told me it was leaking. I said I would fix it. Little did I know floor jacks were fascinating tools and even a very old one could be rebuilt with a cheap rebuild kit. I found the exact floor jack on Craigslist and rebuilt that one and made a video for Youtube Muddy Ruttzz. Comments on that video made me realize a fill and bleed video was a video I should make.
Conclusion: Don't Throw That Old Floor Jack Away!
Floor jacks by their very nature are robustly constructed. They are prime candidates for rebuilding and reusing. You can find a rebuild kit for about any of them. Unlike many other products we run across they are not single use, throw away items. Take the time to examine your leaky floor jack and rebuild it. It will be a educational and satisfying experience.
Thanks for checking out my article and I hope it helps you out!
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