One way to tell if an hydraulic cylinder is going bad on your car lift is to look for oil coming out of the top of it when you raise the car lift up and down. The appearance of oil means that the seal on the cylinder is now leaking and you need to fix and/or replace it before you have a catastrophic failure of the cylinder. Here is how to replace the cylinder on a car lift.
A hydraulic hose runs through the backside of the metal leg on the car lift while the cylinder itself sits in a semi-enclosed space in the front of the leg. You need to disconnect the hose on the backside before you can lift the cylinder out on the front side.
The pipe connection to the hydraulic cylinder comes out of the hole at the bottom of the leg and into a metal elbow. A hose is attached to the top end of the elbow. You need to unscrew the nut holding the hose fitting to the elbow to remove the hose. Make sure you have a catch basin or rags to catch any hydraulic fluid that drains out of the hose fitting once you disconnect it from the metal elbow. You also need to remove the elbow from the pipe connection and then unscrew the pipe connection from the cylinder.
Go back to the front side. There is a heavy chain that goes around a roller wheel at the top of the cylinder. The chain is what pulls the lifting arms up and down to lower and raise a vehicle. Press down on the top of the cylinder to loosen the chain so you can pull it over the top of the roller wheel.
You can pull the cylinder out of the leg once the chain over the top of it has been removed. The hydraulic cylinder will be heavy and you'll have to be careful not to pinch your hands and fingers when you lift it up over a metal plate on the front of the leg.
Slide the new cylinder over the metal plate in the front of the leg and drop the rounded notch on the bottom of the base on the cylinder into the small hole at the bottom of the leg. The notch in the hole keeps the cylinder from sliding out of the leg once the heavy chain is placed back over the top of the roller wheel on the new cylinder.
Go to the back side of the leg. Screw the pipe connection into the new cylinder. Screw the elbow onto the other end of the pipe connection and reconnect the hose fitting to the elbow. Make sure you use pipe sealant on the threads of the hose fitting and pipe.
Add fluid to the hydraulic fluid reservoir on the cylinder to replace any that you may have lost during the leak and when you removed the hose fitting. Open the bleed valve at the top of the cylinder and raise the legs on the car lift a few times until fluid comes out of the bleed valve. This will remove any air that might be in the cylinder.
Close the bleed valve once fluid comes out. The car lift is now ready to use again. To learn more, contact a company like Florida TRUCK & Trailer CO.