Makita 213981-1 — Genuine Makita O‑ring 27
Restore the seal in your Makita rotary hammer with this genuine Makita O‑ring (part no. 213981-1). It’s the rubber sealing ring used on the piston/cylinder/striker area of Makita rotary hammers, listed in Makita parts diagrams as “O‑RING 27.”
Fits Makita Models : HR4510C / HR4501C and HR4511C rotary hammers.
Key details: nominal inner diameter 27 mm (designation “27”), which in standard metric O‑ring sizes corresponds to a 3.0 mm cross‑section (giving an outer diameter of about 33 mm) — the common metric 27×3 O‑ring profile. It’s a precision rubber sealing ring made to sit in the cylinder/striker groove and keep lubrication in while keeping dust and debris out.
Packaged/sold as the single replacement O‑ring called out in the Makita parts list; replace the worn or perished ring to restore impact consistency and prevent internal leakage.
(If your model’s parts diagram shows 213981‑1, this is the original Makita replacement to use.)
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