Cylinder Repair and Reseal Basics
A leaking hydraulic cylinder loses force, drips oil and puts the machine at risk. Often a new seal kit is enough if the rod and barrel are still within tolerance. This guide shows how to judge the damage, pick the right seal kit and reseal the cylinder properly.
View hydraulic cylindersWhen is resealing worth it instead of replacement?
Not every leak means a total loss. If oil drips at the rod or the cylinder drifts under load, the seals are usually worn. As long as the rod and barrel are within tolerance and free of deep scoring, resealing is far cheaper than replacement. Scoring deeper than the chrome layer, pitting or a bent rod point instead to a new cylinder or rod reconditioning.
How do I identify the right seal kit?
A seal kit contains the rod seal, piston seal, wiper, guide bands and O-rings. What matters are the piston and rod dimensions, the cylinder design and the seal profile. The seal material follows the medium and temperature: NBR for standard hydraulic oil, FKM for high temperatures and polyurethane for abrasion-resistant rod seals.
- Measure and record piston diameter, rod diameter and stroke exactly.
- Keep the old seals as samples and compare the profile.
- Set the medium and maximum temperature to choose the material.
How do I disassemble and reassemble correctly?
Cleanliness is decisive when resealing. Depressurise the cylinder, catch the oil and work in a dust-free area. Note the order of the parts during teardown. Wet the new seals in clean hydraulic oil before fitting, use assembly sleeves over sharp edges and seat the guide bands correctly so nothing cants.
Frequently asked questions
Why is my hydraulic cylinder dripping at the rod?
Usually the rod seal is worn or the wiper has let dirt through. As long as the rod is within tolerance and free of deep scoring, a new seal kit is enough. Check the running surface before assembly.
Which seal material should I choose?
NBR is the standard for hydraulic oil up to about 80 °C. For high temperatures or aggressive media use FKM, and polyurethane for abrasion-resistant rod seals. The medium and maximum temperature of your system decide.
Can I reseal a hydraulic cylinder myself?
For simple standard cylinders, yes, if you work cleanly and know the dimensions. A dust-free area, the correct seal kit and gentle fitting over sharp edges are key. A damaged running surface needs reconditioning.
Find the right seal kit
Our hydraulics specialists help with dimensions, material and profile for your cylinder.
Vetted selection
Seal kits matched to dimension and design.
Focus on tightness
Material chosen by medium and temperature.
Safe assembly
Teardown and fitting explained step by step.
Expert advice
Hydraulics specialists support your selection.