Pin wrench

Pin Wrench

HYDRAULIC cylinder overhaul


The overhaul of most hydraulic cylinders is quite easy.


Step one is to clean the cylinder well. Don't work on a dirty cylinder.


Step two is to remove the cylinder head. It may be retained in a number of ways, but most Italian cylinders seem to use pin wrench heads. These threaded heads have two or more holes in the head plate for a pin wrench to remove it. If you don't have a pin wrench, a good substitute can be made by drilling appropriate holes on the jaw sides of a large crescent wrench. Hardened pins (needles available from auto parts stores) can then be temporarily used to turn the head off. Make sure the pins are a decent fit to the holes or you will torment them. Ferrari sometimes used a "wire lock" cylinder head which is a bit unusual in North America. In this case a special size wire is fed into a groove and must be removed before the head will come off. It must be carefully pulled out with a pliers.


Step three is to remove the piston from the rod. If the rod has a flat end that can be held in a vice, simply clamp the end in a vice and turn the lock nut off. Pasquali rods have a swivel end on them and need to be treated differently. DO NOT CLAMP THE ROD IN A STANDARD VICE, IT WILL DAMAGE IT. Simply take a 3/4 inch drive impact wrench and set it to reverse. Hold the rod firmly in your hand and remove the nut with the impact wrench. It will come off surprisingly easy. Remove the piston from the rod. Normally there will be an O-ring below the piston. Set each piece out on the bench in proper order


Step four is seal disassembly. Pasquali and Ferrari lift cylinders use the piston seal type at the right. It's a two part piston seal made from a white nylon bearing and a neoprene seal. Gently pry these type of seals off of the piston using a thin flat blade screw driver. O-ring types should be removed with a dull dental pick or O-ring removal tool. It's important to note the orientation of seals if they have lips or flair. Remove the wiper and rod seal from the head using a pick.


Step five is to clean everything really well, including the inside of the cylinder barrel.


Step six is to carefully inspect the cylinder rod. Normal wear and tear can be hard on the rod and it's not uncommon to find small dings or dents here and there. Carefully dress down any raised areas like ridges from these dings using a fine Arkansas oil stone or an extra fine file. You want to remove the raised portions (which will damage the new seals) without damaging the rod. Polish the area(s) with crocus cloth then clean everything well. Test the rod surface using the original rod seal. Clean it well and oil it. Sliding it up and down the length of the rod, there should be no places where it snags on anything. The tiniest dings can create a ridge and you will feel it when you slide the seal up and down. Inspect the cylinder. Some staining or very slight corrosion can often be overlooked, simply clean everything and polish with crocus cloth.


Step seven is to replace the seals on the piston and replace the rod seal and wiper in the head. Oil all seals really well during assembly. Slide the head onto the rod first, then the assembled piston on to the rod.


The style of piston seal used in Ferrari and Pasquali lift cylinders may not be particularly common to your area. If you have trouble finding seals, we normally stock rebuild kits. So if your hydraulic cylinder is leaking, think about overhauling it yourself. By doing the work, you can overhaul the entire cylinder for about the same price a shop will replace a single rod seal.