Check Valve Kit – Fits Mercury Marine/MerCruiser Engines (Replaces 21-30430A3)
Check Valve Kit – Fits Mercury Marine/MerCruiser Engines (Replaces 21-30430A3) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This Check Valve Kit is designed as a direct replacement for various Mercury Marine and MerCruiser outboard and sterndrive engines, primarily from the 1970s to the 1990s. It ensures proper fuel flow and prevents backflow, restoring original performance and reliability.
This part serves as a direct interchange for Mercury part number 21-30430A3, GLM 700-40190, and Quicksilver 21-30430A3.
- Installs as a direct replacement for the original part.
- Designed for gasoline fuel systems.
- Uses a standard fuel line connection for easy setup.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number |
|---|---|
| Mercury | 21-30430A3 |
| GLM | 700-40190 |
| Quicksilver | 21-30430A3 |
Engine & Model Compatibility
Confirm your engine model and serial number range in the table below to ensure correct fitment.
For Mercury Marine Engines: Check that your engine's serial number falls within the specified range for your model.
| Brand | Model | Rated HP | Years (Serial Number) | OEM Part No. |
|---|---|---|---|---|
| Mercury | 400 (2 CYL.) | 2874704-3336257 | 21-30430A3 | |
| Mercury | 402 | 3336258-4117709 | 21-30430A3 | |
| Mercury | 402 | 3339688-9076838 | 21-30430A3 | |
| Mercury | 402 | 3340783-7047607 | 21-30430A3 | |
| Mercury | 402 | 4117710-4860102 | 21-30430A3 | |
| Mercury | 402 | 7047608-7112422 | 21-30430A3 | |
| Mercury | 402 | 8002335-8027439 | 21-30430A3 | |
| Mercury | 402 | 8027440-8052124 | 21-30430A3 | |
| Mercury | 402 | 9076839-9184450 | 21-30430A3 | |
| Mercury | 402, 40 (2 CYL.) | 40 | 4860103-5556229 | 21-30430A3 |
| Mercury | 402, 40 (2 CYL.) | 40 | 7112423-7144762 | 21-30430A3 |
| Mercury | 402, 40 (2 CYL.) | 40 | 8052125-8064749 | 21-30430A3 |
| Mercury | 402, 40 (2 CYL.) | 40 | 9184451-9251455 | 21-30430A3 |
| Mercury | 650 (3 CYL.) | 65 | 3293184-3525440 | 21-30430A3 |
| Mercury | 650 (3 CYL.) | 65 | 3547987-4382056 | 21-30430A3 |
| Mercury | 650 (3 CYL.) | 65 | 4382057-4571651 | 21-30430A3 |
| Mercury | 650 (3 CYL.) | 65 | 7013633-7073472 | 21-30430A3 |
| Mercury | 650 (3 CYL.) | 65 | 7073473-7087822 | 21-30430A3 |
| Mercury | 650 (3 CYL.) | 65 | 8006640-8042349 | 21-30430A3 |
| Mercury | 650 (3 CYL.) | 65 | 9020074-9112988 | 21-30430A3 |
| Mercury | 650 (3 CYL.) | 65 | 9112989-9135824 | 21-30430A3 |
| Mercury | 800 (4 CYL.), 80 (4 CYL.) | 80 | 2559001-3493912 | 21-30430A3 |
| Mercury | 1150 | 115 | 2836019-3525440 | 21-30430A3 |
| Mercury | 1150 | 115 | 3525441-4855152 | 21-30430A3 |
| Mercury | 1150 | 115 | 7010763-7112248 | 21-30430A3 |
| Mercury | 1150 | 115 | 8008665-8051949 | 21-30430A3 |
| Mercury | 1350 | 135 | 2839369-3293233 | 21-30430A3 |
| Mercury | 1400 | 140 | 3293234-3502805 | 21-30430A3 |
| Mercury | 1500 | 150 | 3502806-4865677 | 21-30430A3 |
| Mercury | 1500 | 150 | 7010533-7112772 | 21-30430A3 |
| Mercury | 1500 | 150 | 8005615-8052649 | 21-30430A3 |
Technical Specs
- Product Type
- Check Valve Kit
- Installation
- Direct replacement
- Fuel Type
- Gasoline
- Connection
- Standard fuel line connection
- Dimensions
- 12.0" L x 11.0" W x 1.5" H
- Weight
- 0.03 lbs (0.014 kg)
What’s in the Box
- 1x Check Valve Kit
Installation Notes
- Ensure the engine is off, cool, and disconnected from the battery.
- Relieve fuel system pressure following the manufacturer's service manual.
- Place an absorbent cloth under the existing valve to catch fuel spillage.
- Carefully disconnect the fuel lines from the old check valve.
- Remove the original valve from its mounting.
- Install the new check valve, ensuring the arrow on the housing points in the direction of fuel flow.
- Securely reconnect and clamp the fuel lines.
- Reconnect the battery, prime the fuel system, and carefully check for any leaks before starting the engine.
Troubleshooting & FAQ
How do I know if my check valve has failed?
Common signs of a faulty check valve include difficulty starting the engine, stalling, rough idling, or loss of fuel prime. The engine may take longer to start as the fuel pump has to re-pressurize the lines. A visual inspection may also reveal fuel leaks around the valve body.
What is the function of this check valve?
This valve maintains pressure in the fuel line, preventing fuel from flowing back into the tank when the engine is off. This ensures that fuel is immediately available at the injectors or carburetor when you start the engine, allowing for quicker and more reliable starts.
Can this part fit models outside the listed serial numbers?
We can only guarantee fitment for the engine models and serial number ranges listed. Using this part on other models is not recommended, as internal specifications may differ. Always verify fitment using the provided compatibility table.
Is there a recommended replacement interval for this part?
There is no fixed replacement interval for a check valve. It should be replaced if it fails or during a major fuel system overhaul. Regularly inspect fuel lines and components for wear, cracking, or leaks as part of your routine maintenance.
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 a 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
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