Part Identification
How to Identify Excavator Hydraulic Cylinder Seal Kits
Confirm boom, arm and bucket cylinder seal kits using cylinder position, assembly reference, machine data and accurate measurements.
Quick answer
Identify the exact cylinder position first—boom, arm or bucket—then use the machine model and serial number, cylinder assembly number or seal-kit reference. If no reliable number is available, a technician may need to measure rod, bore, gland and seal-groove dimensions after safe disassembly. A general excavator model is not enough to select a seal kit.
Identify the cylinder position correctly
Boom, arm and bucket cylinders perform different functions and normally use different dimensions and seal kits. Multi-boom or special-attachment machines may have additional cylinders.
Photograph the complete installed cylinder and clearly mark which cylinder is leaking. For loose cylinders, label the position before sending photos.
- Boom cylinder
- Arm or stick cylinder
- Bucket cylinder
- Blade, offset, attachment or auxiliary cylinder
Find cylinder and kit references
Look for an engraved cylinder number, metal plate, service label or old package reference. Send the complete number, including prefixes and suffixes.
A machine parts manual reference can help, but the machine serial number should still be checked because cylinder specifications can change by production range.
- Cylinder assembly number
- Seal-kit service reference
- Machine model and serial number
- Old packaging or purchase record
Measure only when identification numbers are unavailable
Measurements should be taken by a qualified technician after the hydraulic pressure is safely released and the cylinder is dismantled. Rod and bore diameter alone may not identify every seal.
Arrange removed seals in installation order and photograph each profile beside a scale. Record gland, piston and groove dimensions with suitable measuring tools.
- Rod diameter
- Cylinder bore diameter
- Gland and piston dimensions
- Seal groove width and diameter
- Seal profiles and installation order
Check the condition of related surfaces
New seals will not correct a scratched rod, damaged gland, corroded surface or excessive bushing play. Inspect hard-chrome condition, cylinder tube, piston and guide rings during repair.
Tell the supplier about temperature, fluid and application conditions if they are unusual. Seal material selection depends on the hydraulic system and operating environment.
- Rod scratches, pitting or corrosion
- Gland and piston wear
- Cylinder tube scoring
- Guide ring and bushing condition
- Correct hydraulic oil and cleanliness
Seal-kit matching routes
| Available evidence | Recommended method | Risk level |
|---|---|---|
| Exact seal-kit number | Confirm number, cylinder position and machine serial | Lowest when all data agrees |
| Cylinder assembly number | Cross-reference cylinder and verify machine range | Low to medium |
| Machine model only | Add serial number and cylinder position before quoting | High if used alone |
| No readable number | Technician measurement and seal-profile comparison | Requires careful dimensional verification |
Buyer checklist before requesting a quote
- Exact cylinder position
- Machine model and serial number
- Cylinder or seal-kit reference
- Installed and removed cylinder photos
- Rod, bore and groove measurements when required
- Photos of old seals arranged in order
Frequently asked questions
Can one seal kit fit boom, arm and bucket cylinders?
Normally no. These cylinders usually have different dimensions and seal arrangements.
Is rod diameter enough to select a seal kit?
No. Bore, gland, piston and groove dimensions or a reliable cylinder reference are also needed.
Why does a repaired cylinder still leak after new seals?
Surface damage, incorrect installation, contamination, wrong seal specification or excessive wear can cause repeated leakage.