21389074 Saildrive Thru-Hull Diaphragm Kit · Fits Volvo Penta 110S / 120S / MS25S / 130S / 150S select, Replaces 872026, 877362

21389074 Saildrive Thru-Hull Diaphragm Kit · Fits Volvo Penta 110S / 120S / MS25S / 130S / 150S select, Replaces 872026, 877362

GHMarine saildrive thru-hull diaphragm / rubber bellows kit — CSKU 23B1029 — for select Volvo Penta saildrive / S-drive units. Primary OEM 21389074 (supersedes 872026). Cross-refs 877362 / REC877362. Legacy references 854934 / 21112450 / 3840050 / 3856597 only when EPC ties them. This is a hull thru-hull water-seal kit for saildrive — not a sterndrive U-joint, exhaust, or shift bellow.

Sister CSKU 22KV028 also sells 21389074 — match the CSKU / package you stock. Need sterndrive AQ / SX / Cobra bellows → other GH pages, not this saildrive kit.

Which kit is this?

It is the rubber thru-hull diaphragm / bellows kit that seals where the saildrive passes through the hull. Confirm EPC or the old kit shows 21389074 (or superseded 872026) for your S-drive model before you order.

It is not a sterndrive U-joint bellow, not an exhaust bellow, not a shift-cable bellow, not an AQ / SX / DPS / Cobra sterndrive part, and not a MerCruiser Alpha/Bravo transom bellows kit.

Signs yours is due

• Saildrive thru-hull diaphragm is cracked, soft, or leaking at the hull opening — stamped 21389074 / 872026 / 877362 when readable.
• You are on a 110S / 120S / MS25S / 130S / 150S family and EPC calls for thru-hull kit 21389074.
• You almost ordered a sterndrive U-joint or exhaust bellow because the chart only said "bellows" — stop; this page is saildrive thru-hull only.
• Divert: sister 21389074 CSKU → GH 22KV028. Sterndrive rubber → other GH bellows CSKUs, not 23B1029.

Will it fit my drive?

This kit is Compatible with select Volvo Penta saildrive / S-drive units that specify 21389074 (or superseded 872026), including representative families 110S / 110S-B, 120S-A/B/C/D/E (EPC-gated variants), MS25S / MS25SR, 130S/SR, and 150S/SR when EPC confirms. Some 110S need extra gasket 853946; some MS25S need 3817355 — those are not assumed in this box unless your carton shows them. Sterndrive / AQ / SX / DPS / Cobra is not this page. Do not shop by HP or a calendar year alone.

*Final fit = OEM 21389074 on the saildrive EPC / old kit. Not for sterndrive applications.

OEM & swap numbers

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

Wrong part? Read before you order

• NOT a sterndrive U-joint / exhaust / shift bellow
• NOT AQ / SX / DPS / Cobra sterndrive rubber
• NOT a MerCruiser Alpha / Bravo transom multi-bellow kit
• NOT an automatic include of 853946 / 3817355 / 22222853 unless carton/EPC says so
• NOT HP-only or "year to 2026" shopping without EPC

What ships in the box

• 1 × Saildrive thru-hull diaphragm / rubber bellows (kit 21389074 path)
• Required kit gaskets / cover plate when your package includes them — confirm against the carton (single-diaphragm gallery photos do not prove every kit accessory)

Gallery note: current 23B1029 stock photos may show only the black ring diaphragm. Sister CSKU 22KV028 has a fuller kit layout photo. Confirm carton contents before claiming every gasket / cover plate ships in this CSKU.

Often ordered with related SKUs

• Sister 21389074 CSKU → GH 22KV028
• Sterndrive bellows / seals → other GH CSKUs (not this page)

Install tips on the saildrive thru-hull kit

Saildrive hull thru-hull diaphragm work. Boat hauled or otherwise secured per the service manual. This is not a sterndrive bellows adhesive / expander script.

1. Confirm EPC / old kit is 21389074 (or superseded 872026) for your S-drive model before opening the hull seal.
2. Photograph orientation and note any model-specific extra gaskets (853946 / 3817355) required by EPC.
3. Remove the old diaphragm / seal stack per the saildrive service manual; clean the mating surfaces.
4. Install the new diaphragm and any included kit gaskets / cover plate in the correct order; torque / clamp per manual.
5. Pressure / leak-check the thru-hull seal before returning the boat to the water.

FAQ

Is this for a sterndrive?

No. 23B1029 is a Volvo Penta saildrive / S-drive thru-hull diaphragm kit only.

Is 23B1029 the same as 22KV028?

Same primary OEM 21389074. This page is CSKU 23B1029 — match the CSKU / package you stock.

Does every carton include all gaskets and the cover plate?

Kit path 21389074 includes the thru-hull diaphragm plus required kit accessories when supplied. Confirm your carton — a single-ring photo alone is not proof of every accessory.

My diagram still shows 872026 — is that OK?

Yes when the supersession path is 872026 → 21389074. Order to 21389074 on this page when EPC shows that path.

Do I need 853946 or 3817355 too?

Only if EPC for your exact S-drive variant lists them. They are not assumed in every 23B1029 carton.

Can I pick by horsepower or year only?

No. Fit is S-drive model / EPC driven — not HP or a calendar year free pass.

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 diaphragm kit family — always confirm OEM number, S-drive model, EPC, CSKU, and package contents before ordering.