Brass Expansion Plug Kit – Fits Mercury/Mercruiser (Replaces Mercruiser: 19-34488, 22-72640, 72640, FI1100751; Volvo Penta: 3853209, 835496; OMC: 3853209)

$64.99 $103.00

Shipping calculated at checkout.

Brass Expansion Plug Kit – Fits Mercury/Mercruiser (Replaces Mercruiser: 19-34488, 22-72640, 72640, FI1100751; Volvo Penta: 3853209, 835496; OMC: 3853209) is backordered and will ship as soon as it is back in stock.

Worry-free returns

You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Brass Expansion Plug Kit provides a comprehensive solution for engine block maintenance, compatible with a wide range of Mercury/Mercruiser, Volvo Penta, and OMC engines. Specific compatibility details are listed in the tables below.

It serves as a direct interchange for Mercruiser part numbers 19-34488, 22-72640, 72640, FI1100751; Volvo Penta numbers 3853209, 835496; and OMC number 3853209.

Constructed from durable brass for excellent corrosion resistance in marine environments.
The kit includes multiple expansion plugs to service various engine block and manifold applications.

Part Number Matrix

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

Brand	Part Number
Mercruiser	19-34488
Mercruiser	22-72640
Mercruiser	72640
Mercruiser	FI1100751
Volvo Penta	3853209
Volvo Penta	835496
OMC	3853209

Engine & Model Compatibility

Confirm your engine model and year in the table below.

For Mercury/Mercruiser engines, this kit fits select 2-stroke and 4-stroke outboards from 1980 onwards, along with various inboard/sterndrive models.

For Volvo Penta and OMC, this kit is listed as compatible with various models. Please use the part number matrix to confirm fitment against your engine's required part number.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury/Mercruiser	Mercury/Mariner Outboards	2.5–25	4-Stroke	1999–2010+	MP0009-208 (Replaces 19-34488, 22-72640, 72640, FI1100751)	Includes models such as 2.5hp, 3.5hp, 4-6hp, 8hp, 9.9hp, 15hp, 20hp (2007+), 25hp, 30hp (1994-05, 2010+), 40hp, 50hp, 60hp
Mercury/Mercruiser	Mercury/Mariner Outboards	6–15	2-Stroke	1986–2006	MP0009-208 (Replaces 19-34488, 22-72640, 72640, FI1100751)	Includes models such as 6hp, 8hp, 9.9hp, 10hp (1995-01), 15hp
Mercury/Mercruiser	Mercury/Mariner Outboards	18–25	2-Stroke	1980–2005	MP0009-208 (Replaces 19-34488, 22-72640, 72640, FI1100751)	Includes models such as 18hp (1980-85), 20hp, 25hp (1980-05)
Mercury/Mercruiser	Mercruiser Inboard/Sterndrive	All			MP0009-208 (Replaces 19-34488, 22-72640, 72640, FI1100751)	Compatible with various Mercruiser models
Volvo Penta	Various	All			MP0009-208 (Replaces 3853209, 835496)	Compatible with various Volvo Penta models
OMC	Various	All			MP0009-208 (Replaces 3853209)	Compatible with various OMC models

Technical Specs

Product Type: Expansion Plug Kit
Housing Material: Brass
Package Dimensions: 20.0 cm x 2.0 cm x 17.0 cm (7.87 in x 0.79 in x 6.69 in)
Weight: 0.40 kg (0.88 lbs)
Warranty: 2 years
Other Attributes: Kit includes multiple brass expansion plugs.

What’s in the Box

1 x Brass Expansion Plug Kit

Installation Notes

Completely drain the engine's cooling system to avoid spills.
Carefully access and remove the old or leaking expansion plugs. This may require a punch and hammer or drilling.
Thoroughly clean the plug sockets in the engine block to remove all old sealant, rust, and debris for a proper seal.
Apply a thin, even layer of a marine-grade sealant to the outer sealing edge of the new brass plugs.
Position the new plug (cup side out) in the socket. Use a driver or socket of the correct size to tap it evenly into place until it is seated straight and flush.
After installing all plugs, allow the sealant to cure according to the manufacturer's instructions before proceeding.
Refill the cooling system, then start the engine and carefully inspect for any signs of leaks around the new plugs as the engine warms up.

Troubleshooting & FAQ

What engines does this expansion plug kit fit?

This kit is designed for a wide range of Mercury/Mercruiser, Volvo Penta, and OMC engines. Please refer to the detailed Engine & Model Compatibility table on this page to confirm if your specific model and year are listed.

How do I know which plug from the kit to use?

This kit contains multiple plugs to cover various applications. You must match the new plug's diameter to the one you are replacing on your engine block or manifold. Always measure the old plug or the socket diameter if you are unsure.

What are the signs of a failing expansion plug?

Common symptoms include visible coolant leaks (often green or orange residue) on the side of the engine block, engine overheating from coolant loss, and a persistent low coolant level. Look for corrosion or rust trails originating from the plugs.

Should I replace all the plugs at once or just the leaking one?

While you can replace only the single failing plug, it is often recommended to replace them all at the same time, especially on an older engine. The other original plugs have been exposed to the same conditions and may fail soon, preventing future repairs.

Is this aftermarket kit different from the OEM parts?

This listing is for an aftermarket replacement, not an OEM part. It has been engineered to meet or exceed original equipment manufacturer specifications using comparable high-quality, corrosion-resistant brass. It is manufactured in an ISO 9002 certified facility and is batch-inspected for quality and consistency.

How fast do you ship and what are the costs?

We ship worldwide quickly—typical transit is 5–15 days to most regions. Standard shipping is free for most orders, with expedited options available at checkout for an additional fee.

What is the warranty and return policy?

This product is covered by a 2-year warranty against manufacturing defects under normal marine use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our full policy page or contact us for instructions.

Safety & Important Info

Verify images and specifications against your original part before ordering. If anything differs—even if your model is listed as compatible—do not purchase.
This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
Professional installation is strongly recommended for safety and to ensure optimal performance and a leak-free seal.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world reliability.
Fast Global Fulfillment — With free standard delivery to most regions, you can expect your parts in 5–15 days.
Manufacturer-Direct Value — We offer fair pricing by eliminating middlemen, without ever compromising on materials or quality control.

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