Check Valve Kit – Fits Mercury/Mercruiser 650 65HP Outboard (Replaces 21-30430A4)

$13.99 $22.00

Shipping calculated at checkout.

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 Check Valve Kit – Fits Mercury/Mercruiser 650 65HP Outboard (Replaces 21-30430A4) is engineered for Mercury/Mercruiser 650 65HP 4-cylinder outboard engines from 1970–1971. It ensures reliable engine performance with original equipment quality and fit.

This component serves as a direct replacement for several OEM and aftermarket parts, including Mercury 21-30430A4, Mercury 30430A4, and Hardin Marine 700-40200.

Designed for direct replacement installation.
Suitable for gasoline-fueled marine engines.
Engineered for optimal engine performance and fuel system reliability.

Part Number Matrix

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

Brand	Part Number
Mercury	21-30430A4
Mercury	30430A4
Hardin Marine	700-40200

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury/Mercruiser engines, this part fits specific models within a defined serial number range. Please verify your serial number before ordering.

Brand	Model	Rated HP	Years	OEM Part No.	Notes
Mercury	650 (4 CYL.)	65	1970–1971	21-30430A4	Serial #2803562 THRU 3293183

Technical Specs

Product Type: Check Valve Kit
Installation: Direct replacement
Fuel Type: Gasoline
Dimensions: Length: 120.0 mm, Width: 115.0 mm, Height: 15.0 mm
Weight: 0.01 kg (0.022 lb)
Warranty: 1 Year (Hardin Marine)
Other Technical Attributes: Designed for optimal engine performance

What’s in the Box

Check Valve Assembly (21-30430A4)

Installation Notes

Ensure the engine is off and cool. Disconnect the battery and relieve any pressure from the fuel system for safety.
Locate the existing check valve in the fuel line. Note its orientation, as flow direction is critical.
Carefully disconnect the fuel lines from the old valve. Have rags ready to catch any residual fuel.
Remove the old check valve from its mounting or position.
Install the new a check valve, making sure it is oriented in the correct direction of fuel flow.
Securely reconnect the fuel lines to the new valve and ensure all fittings are tight to prevent leaks.
Reconnect the battery, prime the fuel system according to your engine's manual, and start the engine. Check thoroughly for any fuel leaks around the new valve and connections.

Troubleshooting & FAQ

Is this check valve compatible with my engine's serial number?

This kit is specifically designed for Mercury 650 (4 CYL.) 65HP models from 1970–1971 with serial numbers in the range of 2803562 through 3293183. Please verify your serial number falls within this range before purchasing.

What are the symptoms of a failing check valve?

Common signs of a faulty check valve include difficulty starting the engine, poor or rough idling, engine stalling, inconsistent fuel pressure, or the engine taking longer than usual to start after being turned off (loss of prime).

Is there a correct orientation for installation?

Yes, check valves are directional and must be installed correctly to function. There is typically an arrow on the valve body indicating the direction of fuel flow. The arrow should point away from the fuel tank and towards the engine.

How often should this part be replaced?

There is no mandatory replacement interval. The check valve should be inspected during regular fuel system maintenance and replaced if it shows signs of physical damage, sticking, or is failing to hold pressure.

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.