A seal kit to rebuild a leaky hydraulic cylinder is always cheaper than the cost of a new cylinder. But there are times when it is more economical (not necessarily cheaper) to install a new cylinder.
For example: A 20-year-old cylinder from a field cultivator that’s leaking around its shaft has cycled thousands of times. The leaky seal in the end cap may be due to damaged seal lands/grooves where the end cap has repeatedly slammed into its mechanical stop. That entire end cap will have to be replaced. But when the cylinder is disassembled, examination of its barrel may show that those thousands of cycles have also worn the i.d. of the barrel beyond specs. The cost of a new end cap, barrel and seal kit is probably 2/3 the cost of a new cylinder.
If it’s a simple tie-rod cylinder with four long bolts holding on the end caps, and you can do the work yourself, rebuilding is probably the way to go. But if it’s a more complicated cylinder like a double-acting, re-phasing cylinder with two pistons, that needs to be repaired by a shop which charges by the hour, it may be more economical to simply buy a new cylinder.
Another consideration: What caused the seals in the hydraulic cylinder to start leaking? If the shaft seals got torn up by a rust-pitted shaft, or the piston seals were torn or cut by scoring on the inner surface of the barrel, new seals will quickly be chewed-up by the worn or damaged parts. It’s a waste of time and money to install a seal kit in a cylinder which has physical, mechanical damage.
O-rings and seals in hydraulic cylinders generally don’t fail or start leaking on a whim. Don’t install a seal kit without identifying and repairing the true cause of the leak.
Read More: Fun With Hydraulic Cylinders
