Short answer
Repair the cylinder when the barrel and rod are sound and the failure is seals, a honeable score, or a re-chromeable rod — that is most failures, and a rebuild costs a fraction of new. Replace it when the barrel is pitted through or bulged, the rod is bent or deeply scored past re-chroming, the mounts are cracked, or when a new unit's price and lead time beat the repair. A free teardown evaluation removes the guessing: you get a written quote on the rebuild before any work starts.
When is it worth repairing a hydraulic cylinder?
A rebuild is usually the right call when the two expensive parts — the barrel and the rod — are still good. Leaking seals, a bore that cleans up with a hone, and a rod that can be re-chromed or replaced are all routine rebuild work, and they cost far less than a whole new cylinder. Most cylinder failures fall into this category.
Repair also wins when the cylinder is custom, obsolete, or hard to source, because a rebuild reuses the parts you already have that fit the machine. If the mounts, pins, and porting are all correct and only the wear parts are gone, rebuilding keeps a known-good fit.
When should you replace a cylinder instead of repairing it?
Replace when the core structure is compromised: a barrel pitted through or bulged from an over-pressure event, a rod bent or scored too deep to re-chrome, cracked mounting ears, or threads torn out beyond repair. At that point you are remaking most of the cylinder anyway, and a new unit is the cleaner answer.
Replace, too, when the numbers favor it — if a new cylinder's price and availability beat the rebuild, or if the old design was marginal and you would rather correct it. An honest evaluation says so plainly; if it is cheaper or better to build new, that is the recommendation you should get.
How do you decide when you are down and losing money?
When a machine is stopped, downtime often outweighs the parts decision. Compare the realistic turnaround on a rebuild against the lead time on a replacement, and factor in whether you have a spare to run in the meantime. Sometimes the fastest path back to running decides it, not the lowest parts cost.
The way to remove the uncertainty is a teardown evaluation: the cylinder comes apart, every seal surface is measured, and you get a written quote showing what needs replacing, what can be reused, honed, or re-chromed, and the cost — before any work is authorized. Nothing gets rebuilt until you approve the number.