When Your 4-Post Lift Craps the Bed . . .
Posted: Fri Dec 01, 2023 11:07 am
So, about a month ago, one of the two 4-post lifts that I have in my garage started puking hydraulic fluid out of the end opposite to the piston goes in and out. So, basically, it was spewing oil out of a spot that appears to be just a solid end piece. My initial assumption was that the weld broke where the end piece is welded to the cylinder. That was not the case, which is actually good news.
After ciphering on it a bit, I realized that when the lift is in the full up position, the piston is in the retracted position (which pulls the cables to lift the parking deck). I had always thought that the piston extended to make the lift go up. Not so, however. Basically, the end of the piston (the end that slides back and forth inside the cylindrical housing) has a seal to prevent oil from getting past it. The oil is pumped from the motor to the space between the end of the piston and the open end of the hydraulic cylinder where the piston slides in and out. When the piston is sliding back and forth inside the cylinder, air will enter and exit the cylinder to fill the space between the end of the piston and the end piece that's welded onto the cylinder (where the oil was spewing out of), and that's done through a vent in the endcap that's very difficult to see. What had happened to mine was that the seal on the end of the piston had failed, which allowed oil to enter into the space between the end of the piston and the welded on cap at the end of the cylinder. When I raised the lift, the end of the piston moved further inside the cylinder, and that pushed the wayward oil seepage out of the invisible air vent (a lot of oil).
I bought these two lifts in 2008, so 15 years isn't bad for a seal. I expect the other one to go out soon. For the record, I bought these lifts from Greg Smith Equipment, which has since been bought out by Tooltopia. They still sell lifts, but apparently not this "brand" anymore. Mine are "Direct-Lift PP8Plus".
Rather than calling for a lift repair technician, I removed the hydraulic cylinder myself, which wasn't that difficult. I did use a transmission jack to support it during removal and installation. There was a hydraulic cylinder repair shop about a mile away from my office. It took them exactly 3 weeks to get it rebuilt. Total cost with tax was $437. I got it put back together and working fine, so a relatively happy ending. Just waiting now for the other one to go out. Here are some photos I took during the troubleshooting and repair process.
After ciphering on it a bit, I realized that when the lift is in the full up position, the piston is in the retracted position (which pulls the cables to lift the parking deck). I had always thought that the piston extended to make the lift go up. Not so, however. Basically, the end of the piston (the end that slides back and forth inside the cylindrical housing) has a seal to prevent oil from getting past it. The oil is pumped from the motor to the space between the end of the piston and the open end of the hydraulic cylinder where the piston slides in and out. When the piston is sliding back and forth inside the cylinder, air will enter and exit the cylinder to fill the space between the end of the piston and the end piece that's welded onto the cylinder (where the oil was spewing out of), and that's done through a vent in the endcap that's very difficult to see. What had happened to mine was that the seal on the end of the piston had failed, which allowed oil to enter into the space between the end of the piston and the welded on cap at the end of the cylinder. When I raised the lift, the end of the piston moved further inside the cylinder, and that pushed the wayward oil seepage out of the invisible air vent (a lot of oil).
I bought these two lifts in 2008, so 15 years isn't bad for a seal. I expect the other one to go out soon. For the record, I bought these lifts from Greg Smith Equipment, which has since been bought out by Tooltopia. They still sell lifts, but apparently not this "brand" anymore. Mine are "Direct-Lift PP8Plus".
Rather than calling for a lift repair technician, I removed the hydraulic cylinder myself, which wasn't that difficult. I did use a transmission jack to support it during removal and installation. There was a hydraulic cylinder repair shop about a mile away from my office. It took them exactly 3 weeks to get it rebuilt. Total cost with tax was $437. I got it put back together and working fine, so a relatively happy ending. Just waiting now for the other one to go out. Here are some photos I took during the troubleshooting and repair process.