21389074 Saildrive Thru-Hull Diaphragm Kit · Fits Volvo Penta 110S / 120S / MS25S select, Replaces 872026, 877362

21389074 Saildrive Thru-Hull Diaphragm Kit · Fits Volvo Penta 110S / 120S / MS25S select, Replaces 872026, 877362

GHMarine saildrive thru-hull diaphragm / rubber bellows kit for select Volvo Penta S-drive / saildrive units — OEM 21389074 (supersedes 872026). Cross-refs 877362 / REC877362. Legacy references 854934 / 21112450 / 3840050 / 3856597 only when your EPC supersession chain lists them. This seals the hull opening around a saildrive — it is not a sterndrive U-joint, exhaust, or shift bellow.

This page is the canonical saildrive thru-hull kit listing. Internal CSKU 23B1029 maps to the same 21389074 kit — do not buy a second page. Some 110S applications also need shim 853946; some MS25S applications also need shim 3817355 — those shims are not default contents of this carton. Clamp ring 22222853 is also sold separately when required.

Which kit is this?

It is the rubber thru-hull diaphragm / bellows kit that keeps the saildrive hull opening watertight. The carton is built around OEM 21389074: the main rubber diaphragm plus the required kit gaskets and cover plate as supplied in the original package style.

It is not a sterndrive U-joint bellow (3854127 / 876294), not AQ exhaust bellow 876631 / 876633, not SX cone-clutch exhaust 3850426, not a MerCruiser three-bellow transom kit, and not a single diaphragm sold without the kit gaskets when your package is the full 21389074 kit.

Signs yours is due

• Saildrive thru-hull rubber diaphragm is cracked, soft, or leaking at the hull opening — stamped 21389074 / 872026 / 877362 when readable.
• You are hauling a sailboat with an S-drive (110S / 120S / MS25S / 130S / 150S family) and the EPC calls for thru-hull kit 21389074.
• You almost ordered a sterndrive bellows pack because the word "bellows" looked familiar — stop: this is a saildrive hull seal kit.
• Divert: sterndrive U-joint → GH 18B5002 / 17B1016. AQ exhaust with flapper → GH 25B1095. Need only a model-specific shim → order that shim separately.

Will it fit my saildrive?

This kit is Compatible with select Volvo Penta saildrive / S-drive units that specify 21389074 (or superseded 872026) — including representative families 110S / 110S-B, 120S-A/B/C/D/E, MS25S / MS25SR, 130S/SR, and 150S/SR when EPC confirms the variant. Drive model code and EPC decide fit — not horsepower, and not an open year band through 2026.

*Not for sterndrive / AQ / SX / DPS / Cobra bellows applications. Final fit = OEM 21389074 on the saildrive EPC / old kit.

OEM & swap numbers

Primary OEM 21389074 (replaces 872026). Cross-refs 877362 / REC877362. Legacy chain numbers only when EPC lists them.

Wrong part? Read before you order

• NOT a sterndrive U-joint / exhaust / shift bellow
• NOT AQ U-joint 876294 (GH 17B1016)
• NOT AQ exhaust 876631 / with-flapper 876633 (GH 17B1008 / 25B1095)
• NOT SX exhaust 3850426 (GH 17B1010)
• NOT Cobra/SX U-joint 3854127 (GH 18B5002)
• NOT a second page for the same kit (internal 23B1029 — use this page)
• NOT a carton that defaults to shims 853946 / 3817355 or clamp ring 22222853 unless your package proves them

What ships in the box

• 1 × Saildrive thru-hull diaphragm / rubber bellows (kit 21389074)
• Required kit gaskets and cover plate as supplied in the package

Confirm package contents against your carton. Shims 853946 / 3817355 and clamp ring 22222853 are not claimed as default contents. Hose clamps are not claimed unless your package shows them.

Often ordered with related notes

• Some 110S variants also need shim 853946 (separate)
• Some MS25S variants also need shim 3817355 (separate)
• Clamp ring 22222853 when the assembly requires it (separate)

Install tips (saildrive thru-hull)

Saildrive / S-drive thru-hull diaphragm service — not a sterndrive transom bellow job. Support the boat; follow the Volvo Penta saildrive procedure for thru-hull diaphragm / bellows kit replacement for your exact S-drive model. Do not copy a sterndrive adhesive / expander / three-bellow sequence from another product page.

1. Confirm EPC / old kit is 21389074 (or superseded 872026) for your S-drive model — not a sterndrive bellow OEM.
2. Haul / support the sailboat as required; access the thru-hull diaphragm per the saildrive service manual.
3. Remove the old diaphragm and kit gaskets/cover plate; clean the mating surfaces.
4. Install the new kit components in the order shown for that S-drive; add model-specific shims only if your EPC calls for them separately.
5. Reassemble; check for hull leaks before returning the boat to service.

FAQ

Will this fit my sterndrive?

No. This kit is for Volvo Penta saildrive / S-drive thru-hull sealing. Sterndrive bellows are different SKUs.

Is this the same as 23B1029?

Same OEM kit 21389074. This page is the canonical listing — do not order a second page.

Does the box include shim 853946 or 3817355?

Not by default. Some 110S / MS25S variants need those shims separately — confirm your EPC.

Is 872026 still the current number?

872026 is the superseded prior kit number. Order to 21389074 on this page when EPC shows that path.

Do I use sterndrive bellows adhesive and an expander tool?

Follow the Volvo Penta saildrive thru-hull procedure for your model. Do not assume a sterndrive three-bellow adhesive recipe.

What comes in the box?

Kit 21389074: thru-hull diaphragm plus required kit gaskets and cover plate as supplied — confirm against your package.

Please note

Aftermarket replacement by GHMarine. Not affiliated with engine manufacturers named above. "Compatible with", "Replaces", and cross-ref numbers identify the 21389074 saildrive thru-hull kit — always confirm S-drive model, EPC, and package contents before ordering. Not for sterndrive bellow applications.