Quickjack Hydraulic Fluid Contamination and Quickconnect Fitting Failures

I had the BMW wagon in the garage up on the quickjack for a few weeks at the start of September, fixing a Low Boost Pressure code, oil pan leak, replacing rear drive axles, and treating some underbody and rear bumper corrosion

I've had the Quickjacks for two years now - they've been a great tool, really useful to quickly get all four wheels in the air for doing seasonal tire changes, or drivetrain maintenance. Halfway through the last job, the hydraulic hoses began to get difficult to reconnect, there was residual hydraulic pressure in the hoses. I was in a hurry, so I tried forcing the connectors onto the pump. The next time I hit the lift control, I started losing a lot of hydraulic oil from the quick connector. 

Quickjack hydraulic pump releasing its schmoo

It didn't take long to figure out the problem - forcing the connectors cut the o-rings in the face of the connectors. I trashed two connectors of the four female connectors. 

Notice the protrucing piece of O-ring left of the center pin

I was in the middle of raising the car and I wanted to get the next step of the job done, so I simply removed the bad connectors and made fixed hose connections, using 3/8" NPT unions, and a 3/8" bulkhead fitting to replace one of the pump male quick connectors. However, I had lost a lot of fluid. I went to my automotive fluid bin and grabbed a bottle of brake fluid. Big mistake. The spec is for automatic transmission fluid, and I added about a pint of brake fluid and got back to business. 

Two days later I went to lower the car - and the cylinders wouldn't hold the car raised without the buttons pressed. I had difficulty removing the lift locks so that I could lower the car. Fluid was bypassing the check valve that holds the car in the air when there isn't any button input. I removed the check valve, and found little bits of white plastic jamming the check valve open. 

Quickjack check valve - marked with a CV on the valve body.

Not good news - but I immediately realized the contaminated fluid was the probable cause. Once I was done with the Quickjacks, I drained all the fluid from the system - removed the reservoir, removed the quick couplings from the hoses, and stood the jacks up to drain the cylinders by gravity. 

Draining fluid from hoses and jack cylinders by gravity

When I opened the reservoir, that's where I encountered the real mess. Bits of white plastic suspended in hydraulic fluid. Larger chunks in the bottom of the reservoir. The inlet strainer was detached from the inlet elbow, and just lying in the bottom of the reservoir.  

Inlet strainer (round) detatched from inlet elbow.

Bits of white plastic in the reservoir

Inlet strainer missing its attachment hardware (likely made of the white plastic which dissolved)

White plastic in the inlet port of the pump

More white plastic in the pump inlet port

I don't have a replacement inlet strainer yet. I have seen all metal inlet strainers and inlet elbows on the internet - but I'm having difficulty getting my hands on them. For now, I've replaced all the fluid with clean ATF and I'm running the jack without the strainer, just the inlet elbow. I'll drain and flush the fluid a second time once I have an inlet strainer to install. 

A few recommendations from what I've learned the hard way.

1.    Put a label on your quickjack hydraulic reservoir near the fill port - "ATF Only"
2.    Always hold the "down" button for 5 to 10 extra seconds when descending the quickjack, to release as much pressure as possible from your hoses before disconnecting them. This helps prevent residual pressure buildup in the hoses. 

Not my finest hour - but hopefully the information in this post helps someone else avoid the same issue in the future. 



  1. Do you know what size the large rubber washer is near the strainer? My unit is leaking and its definitely the washer.. thanks in advance.

    1. Do you mean the o-ring that seals the reservoir against the pump body? Sorry - don't have that measurement.