Rubber Diaphragm Seal Kit – Fits Volvo Penta Saildrive 110S/120S/130S/150S/MS25S (Replaces 21389074)

$98.50

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Delivery and Shipping

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Product Details

This aftermarket Rubber Diaphragm Seal Kit – Fits Volvo Penta Saildrive 110S/120S/130S/150S/MS25S (Replaces 21389074) is engineered for Volvo Penta saildrives, including the 110S, 120S, 130S, 150S, and MS25S series. It provides a robust, watertight seal for the critical interface between the hull and the saildrive unit, preventing water ingress and protecting mechanical components.

This kit is a direct replacement for Volvo Penta part numbers 21389074 and 854932 (external rubber flap).

Installation: Secures the saildrive to the boat hull.
Seal Type: Includes both the primary internal seal and the external rubber flap.
Core Components: Kit contains the main rubber diaphragm and the external rubber flap for a complete installation.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number	Notes
Volvo Penta	21389074	Main diaphragm seal kit
Volvo Penta	854932	External rubber flap (included in this kit)

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This kit is designed for the following Volvo Penta saildrive units and the engines commonly paired with them.

Brand	Model	OEM Part No.	Notes
Volvo Penta	110S	21389074	Saildrive
Volvo Penta	120S/120SA/120SB/120SC/120SD/120SE	21389074	Saildrive
Volvo Penta	130S/130S-A/130S-B/130S-C/130S-D	21389074	Saildrive
Volvo Penta	130SR/130SR-A/130SR-B/130SR-C/130SR-D	21389074	Saildrive
Volvo Penta	150S/150S-A/150S-B/150S-C/150S-D	21389074	Saildrive
Volvo Penta	150SR/150SR-A/150SR-B/150SR-C/150SR-D	21389074	Saildrive
Volvo Penta	MS25S/MS25S-A/MS25S-R/MS25S-RA	21389074	Saildrive
Volvo Penta	S120C	21389074	Saildrive
Volvo Penta	100S	21389074	Saildrive
Volvo Penta	2001/2001R/2001B/2001D	21389074	Marine Engine
Volvo Penta	2002/2002B/2002D	21389074	Marine Engine
Volvo Penta	2003/2003R/2003B/2003D/2003T/2003TB/2003TR	21389074	Marine Engine
Volvo Penta	MD5A/MD5B/MD5C	21389074	Marine Engine
Volvo Penta	MD6A/MD6B	21389074	Marine Engine
Volvo Penta	MD7A/MD7B	21389074	Marine Engine
Volvo Penta	MD11C/MD11D	21389074	Marine Engine
Volvo Penta	MD17C/MD17D	21389074	Marine Engine
Volvo Penta	MD21A/MD21B	21389074	Marine Engine
Volvo Penta	MD67C	21389074	Marine Engine
Volvo Penta	AQ115A/AQ115B	21389074	Marine Engine
Volvo Penta	AQ130A/AQ130B/AQ130C/AQ130D	21389074	Marine Engine
Volvo Penta	AQ165A	21389074	Marine Engine
Volvo Penta	AQ170A/AQ170B/AQ170C	21389074	Marine Engine
Volvo Penta	B20	21389074	Marine Engine
Volvo Penta	MB20A/MB20B/MB20C	21389074	Marine Engine
Volvo Penta	BB115A/BB115B/BB115C	21389074	Marine Engine
Volvo Penta	BB165A	21389074	Marine Engine
Volvo Penta	BB170A/BB170B/BB170C	21389074	Marine Engine
Volvo Penta	AQD21A/AQD21B	21389074	Marine Engine

Technical Specs

Product Type: Rubber Diaphragm Seal Kit
Installation: Saildrive
Connection: Sail Drive to Hull
Housing Material: Rubber
Housing Color: Black
Fitting Type: External Flap and Internal Seal
Other Technical Attributes: Includes the external rubber flap (part number 854932)

What’s in the Box

1 x Rubber Diaphragm Seal Kit (Replaces 21389074)
1 x External Rubber Flap (Replaces 854932)

Installation Notes

Ensure the vessel is safely and securely hauled out of the water.
Disconnect the engine from the saildrive unit according to the manufacturer's service manual.
Carefully remove the old diaphragm, ensuring all residual sealant and debris are cleaned from the mounting surfaces.
Inspect the mounting rings and hull for any damage or corrosion before proceeding.
Position the new diaphragm seal, aligning it correctly with the bolt holes.
Apply a suitable marine-grade sealant as recommended by the engine manufacturer.
Tighten all fastenings to the specified torque settings in the correct sequence.
Install the external rubber flap.
Once reassembled, perform a thorough leak check before launching the vessel.

Troubleshooting & FAQ

How often should the saildrive diaphragm seal be replaced?

Volvo Penta recommends replacing the saildrive diaphragm every 7 years as a critical maintenance item. Failure to do so can lead to catastrophic water ingress.

What are the signs of a failing diaphragm seal?

Visible signs include saltwater intrusion in the bilge near the saildrive, visible cracks or perishing of the rubber on the internal seal, or water weeping around the saildrive/hull interface. Any sign of degradation warrants immediate inspection and replacement.

Is this kit compatible with both the 130S and 130SR models?

Yes, this kit is fully compatible with all variants of the 130S and 130SR series, including -A, -B, -C, and -D models. Refer to the compatibility table for a full list.

What is the difference between the main diaphragm and the external rubber flap?

The main diaphragm provides the primary watertight seal between the saildrive leg and the boat's hull. The external rubber flap (854932) acts as a secondary barrier and fairing, protecting the main seal from external debris and hydrodynamic forces.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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