Yanmar E990581 - O-ring
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An elastomeric O-ring that seals static and dynamic joints throughout Yanmar engine hydraulic circuits — cylinder end caps, valve bodies, manifolds and fitting faces.
Key details
- Seals hydraulic joints against pressure loss and external leakage
- Sized to the cross-section and inside diameter required for this position, not a generic substitute
- Consumable item — replace on every teardown and never reuse a removed O-ring
- Usually ordered alongside back-up rings, wiper seals and U-cup seals from the same repair position
Specifications
| Part number | E990581 |
| Component type | Hydraulic O-ring |
| Part type | OEM-grade aftermarket |
| Fits brand | Yanmar |
| Category | Engine & Earthmoving |
Where it is used
Components of this type are fitted to the hydraulic system on Yanmar engines. This is category-level context, not a fitment list — confirm the part number against your machine's model and serial number before ordering.
Service notes
Inspect the sealing groove for scoring, burrs and debris before fitting, and lubricate the new ring with clean hydraulic fluid on assembly. A nicked groove will leak regardless of seal condition.
Fitment & availability
This is an OEM-grade aftermarket replacement manufactured to OE specification. It is cross-referenced to Yanmar part number E990581 for identification and is not supplied by the original equipment manufacturer.
Check the part number against your model and serial number before ordering. If this item is not showing as available, use Check Availability and our team will confirm lead time and fitment.