O-Rings

Browse aftermarket O-rings for skid steer loaders, compact track loaders, and excavators, covering hydraulic fittings and valves, fuel system connections, and cooling and engine joints.

Match your O-ring by OEM part number rather than by eye, since inside diameter and cross-section both have to be right. Details are listed on each product page.

O-Ring Fitment and Compatibility

An O-ring is specified by three things: inside diameter, cross-section thickness, and material. Two of those are invisible at a glance. An O-ring one size thinner in cross-section drops into the groove, looks correct, and seals perfectly well at rest, then weeps as soon as the joint sees pressure, because there is not enough material to be squeezed into the gap it is meant to fill. Common replacements include the O-rings replacing OEM 25K30508, 25K30210, 54K30118, 58K120, 79K14, 79K16, 7418836, 6683233, 6558518, and 3974038.

Material matters as much as size. Compounds differ in what fluid and what temperature they tolerate, and an O-ring that is correct in a hydraulic joint can harden, swell, or go brittle in a fuel or high-heat position. Ordering by the OEM number for the joint keeps the compound right without having to identify it.

Types of Replacement O-Rings

Hydraulic O-rings seal fittings, adapters, cartridge valves, and cylinder joints, and they are the largest group here. In pressure positions they are frequently paired with a back-up ring that stops the O-ring extruding into the clearance gap, and a rebuild that leaves the back-up ring out will seal cold and weep once it is hot and loaded.

Fuel system O-rings seal connectors, filter heads, and injection components on the low-pressure side. Cooling and engine O-rings seal thermostat housings, water pump joints, and covers where a flat gasket would not suit the joint geometry.

Fit O-rings dry-free of grit and lightly lubricated with the fluid the joint carries. Most O-rings that fail early were nicked on a thread or a sharp edge on the way in, not defective in the bag.

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Hydraulic System Parts

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