Baffle Plate Gasket – Fits Mercury/Mariner 50–60 HP (Replaces 27-703351)

$3.49 $5.00

Shipping calculated at checkout.

Baffle Plate Gasket – Fits Mercury/Mariner 50–60 HP (Replaces 27-703351) 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 Baffle Plate Gasket – Fits Mercury/Mariner 50–60 HP (Replaces 27-703351) is compatible with Mercury/Mariner 3-cylinder 2-Stroke outboard motors, specifically 50 HP and 60 HP models manufactured between 1987–1990.

It serves as a direct replacement for OEM part number 27-703351 and aftermarket parts WSM 521-16, Sierra 18-0922, and GLM 30800.

Designed for marine, PWC, and offroad applications.

Part Number Matrix

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

Brand	Part Number	Notes
Mercury/Mariner (OEM)	27-703351	Original Equipment Manufacturer part number.
WSM	521-16	Aftermarket cross-reference.
Sierra	18-0922	Aftermarket cross-reference. Source data indicated a "Pkg. of 2" which may apply to the Sierra package, not the gasket quantity needed per engine.
GLM	30800	Aftermarket cross-reference.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This part is compatible with select Mercury and Mariner outboard engines.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury/Mariner	50 (3 cyl.)	50	2-Stroke	1987–1990	27-703351	Fits models with serial numbers 0A721308 & Up, 0B122930 THRU 0D000749, 9469200 THRU 9683054
Mercury/Mariner	60 (3 cyl.)	60	2-Stroke	1987–1990	27-703351	Fits models with serial numbers 0A721308 & Up, 0B122930 THRU 0D000749, 9469200 THRU 9683054

Technical Specs

Product Type: Gasket, Baffle Plate
Dimensions: Length: 15.7 in, Width: 4.1 in, Height: 0.1 in
Weight: 0.009 kg (0.02 lbs)
Applications: Designed for PWC, Offroad, and Outboard applications.

What’s in the Box

1x Baffle Plate Gasket

Installation Notes

Disconnect the battery and ensure the engine has completely cooled.
Access the baffle plate, removing any covers or components that obstruct it.
Carefully remove the old gasket. Use a plastic scraper to avoid damaging the metal surfaces.
Thoroughly clean the mating surfaces, ensuring they are free of old gasket material, oil, and debris.
Position the new gasket, verifying it aligns with all bolt holes and passages.
Reinstall the baffle plate and fasteners. Tighten bolts in a star pattern to the torque specified in your service manual.
Reconnect the battery. After starting the engine, check for any exhaust or water leaks around the gasket area.

Troubleshooting & FAQ

How do I confirm this gasket fits my engine?

Verify your engine model and year against the compatibility table. For Mercury/Mariner models, it's also crucial to check if your engine's serial number falls within the specified ranges listed in the notes.

What are the signs of a failing baffle plate gasket?

Common symptoms include poor engine performance, overheating, or visible exhaust or water leaks around the baffle plate area.

Is this the correct gasket for the exhaust plate?

This is a baffle plate gasket. While it's part of the exhaust system, ensure you are replacing the correct gasket. Always compare your old part to the images and specifications provided before ordering.

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.

Payment & Security

Payment methods

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.