What Does a Pump Seal Kit Contain?
A complete hydraulic pump seal kit includes all the sealing components required for a full pump overhaul in a single, application-matched supply. Depending on the pump type and model, a standard pump seal kit contains:
-
Shaft Seal — The primary rotary seal at the pump drive shaft, preventing hydraulic fluid from migrating outward along the shaft to the external pump face. The shaft seal is the most commonly replaced seal on any hydraulic pump and the first point of visible external leakage.
-
Piston Seals and Slipper Seals — On axial piston pumps, piston seals and bronze slipper pads maintain the critical sealing interface between each piston and the cylinder barrel bore, preventing internal bypass between high and low pressure sides of the pump.
-
Valve Plate Seals — Sealing components at the port plate and valve plate interface, maintaining separation between the intake and discharge ports within the pump barrel assembly.
-
O-Ring Set — A complete set of all o-rings at housing faces, port connections, end cover joints, and internal passages throughout the pump assembly.
-
Gaskets and Back-Up Rings — Flat gaskets and anti-extrusion back-up rings at housing split faces and high-pressure port connections where o-rings alone are insufficient for reliable sealing under full working pressure.
-
Dust Wiper Seal — External wiper seal at the shaft entry point, preventing external contamination from reaching the shaft seal and internal pump components.
When to Use a Pump Seal Kit vs Full Pump Replacement
The decision between a seal kit rebuild and complete pump assembly replacement depends on the condition of the pump's major internal components:
-
Seal kit rebuild is appropriate when — External leakage is detected at the shaft seal or housing faces, and inspection confirms the pump barrel, pistons, valve plate, and housing bore are within serviceable dimensional tolerances. A quality seal kit rebuild at this stage restores full sealing integrity and extends pump service life at a fraction of the complete replacement cost.
-
Full pump replacement is required when The pump barrel bore shows scoring or wear beyond honing tolerance, pistons or slipper pads are damaged beyond the serviceable wear limit, the shaft shows journal damage, or the pump has suffered a catastrophic internal failure from contamination or oil starvation. Attempting a seal kit rebuild on a pump with major internal damage will not restore performance and risks immediate repeat failure.
-
Proactive seal kit replacement — On high-hour machines, replacing pump seals as part of a scheduled overhaul before visible leakage develops is the most cost-effective long-term maintenance strategy preventing the progressive system contamination and downstream component damage that a leaking pump causes over time.
Our parts specialists can help you assess which approach is appropriate for your specific pump condition when you contact our team before ordering.
Pump Seal Kit Models We Supply
Imara Engineering supplies hydraulic pump seal kits for a wide range of excavator pump models and production series. Our most commonly supplied kits include:
-
Komatsu — PC200-7, PC200-8, PC210-8, PC300-7, PC300-8, PC360-7, PC400-7, PC400-8, PC450-8
-
Caterpillar (CAT) — 320C, 320D, 320D2, 323, 325C, 325D, 330C, 330D, 336D, 336E
-
Hitachi — ZX200-3, ZX210-3, ZX300-3, ZX330-3, ZX450-3, ZX500-3, EX200-5, EX300-5
-
Volvo — EC210B, EC240B, EC290B, EC380, EC480, EC700
-
Doosan — DX225LC, DX300LC, DX380LC, DX480LC
-
Kobelco — SK200-8, SK300, SK350-8, SK480, SK850
-
Hyundai — R210LC-9, R290LC-9, R380LC, R480LC
-
Case — CX210, CX300, CX350, CX470
Cannot find your pump model listed? Contact our parts team with your machine serial number, pump type, and OEM part number, and we will confirm the correct seal kit for your specific unit immediately.
Pump Seal Kit Installation: Key Requirements for a Successful Rebuild
A quality seal kit will only deliver its full service life potential if the installation process is carried out correctly. These are the critical requirements for a successful pump seal rebuild:
-
Flush the hydraulic system before installation — Any contamination remaining in the circuit from the failed seals will immediately attack new seal surfaces. A full system flush and filter replacement before installing the rebuilt pump is non-negotiable.
-
Inspect all mating surfaces before fitting new seals — Confirm shaft journal, barrel bore, and housing face surfaces are within tolerance and free of scoring before installing new seals. A new seal against a damaged surface will fail within hours.
-
Use correct seal installation tools — Seals must be pressed squarely into their grooves without twisting, folding, or over-compression. Correct installation of mandrels and drivers prevents installation damage that causes immediate seal failure.
-
Lubricate seals before assembly — All seals should be lightly coated with clean hydraulic fluid or petroleum jelly compatible with the seal elastomer before installation to prevent dry installation damage during initial start-up.
-
Replace the hydraulic filter at the same time — Installing a new or rebuilt pump into a circuit with a contaminated filter immediately exposes new internal components to the debris captured in the old filter element.
-
Run in the rebuilt pump carefully — After installation, run the machine at low load for an initial period to allow new seals to seat correctly before returning to full working pressure and duty cycle.
Related Hydraulic Parts You May Need
Pump seal kit rebuild frequently connects to wider hydraulic system servicing. Consider sourcing these components alongside your pump seal kit:
- Main Hydraulic Pumps — Where pump internal damage extends beyond seal replacement, a complete main pump assembly is the correct solution
- Pilot Pumps — Inspect and service pilot pump seals simultaneously when rebuilding the main pump in a tandem assembly
- Gear Pumps — Gear pump shaft seal replacement is frequently required alongside main pump seal overhaul on combined circuit machines
- Motor Seal Kits — Consider motor seal inspection at the same service event to address all hydraulic circuit sealing in a single maintenance window
- O-Ring Kits — Supplement the pump seal kit with an o-ring assortment kit for all circuit connections and port seals disturbed during the pump rebuild
