Check Valve Kit – Fits Mercury/Mercruiser Marine Engines (Replaces 21-30430A1)
Check Valve Kit – Fits Mercury/Mercruiser Marine Engines (Replaces 21-30430A1) 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 – Fits Mercury/Mercruiser Marine Engines (Replaces 21-30430A1) is designed for a wide range of 4-cylinder and 6-cylinder marine engines from the mid-1960s through the early 1970s. It provides a reliable fuel flow solution for specific Mercury outboards and Mercruiser inboard/sterndrive models.
It serves as a direct replacement for Mercury/Mercruiser part numbers 21-30430A1 and 30430A1, and is an interchange for GLM 40180.
- Installation Method: Direct replacement
- Intended Fuel Type: Gasoline
- Kit Weight: 0.03 kg (0.066 lb)
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/Mercruiser | 21-30430A1 |
| Mercury/Mercruiser | 30430A1 |
| GLM | 40180 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury owners, this kit covers various outboard models from 35 HP to 125 HP manufactured between 1966 and 1972.
For Mercruiser owners, compatibility extends to several inboard and sterndrive models, including specific 4-cylinder and 6-cylinder engines.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | Outboard | 35 | 1966–1969 | 21-30430A1 | ||
| Mercury | Outboard | 65 | 4-Stroke | 1967–1969 | 21-30430A1 | 4-cylinder |
| Mercury | Outboard | 80 | 4-Stroke | 1969–1972 | 21-30430A1 | 4-cylinder |
| Mercury | Outboard | 95 | 1966, 1969 | 21-30430A1 | 6-cylinder | |
| Mercury | Outboard | 100 | 1966, 1969 | 21-30430A1 | 6-cylinder | |
| Mercury | Outboard | 110 | 1966, 1969 | 21-30430A1 | 6-cylinder | |
| Mercury | Outboard | 125 | 1966, 1969 | 21-30430A1 | 6-cylinder | |
| Mercruiser | 1000 BP | 21-30430A1 | ||||
| Mercruiser | 1000 SS | 21-30430A1 | ||||
| Mercruiser | 1100 | 21-30430A1 | ||||
| Mercruiser | 1250 | 21-30430A1 | ||||
| Mercruiser | 1250 BP | 21-30430A1 | ||||
| Mercruiser | 200 | 21-30430A1 | ||||
| Mercruiser | 350 | 21-30430A1 | ||||
| Mercruiser | 500 | 21-30430A1 | ||||
| Mercruiser | 650 | 4-Stroke | 21-30430A1 | 4-cylinder | ||
| Mercruiser | 800 | 4-Stroke | 21-30430A1 | 4-cylinder | ||
| Mercruiser | 80 | 4-Stroke | 21-30430A1 | 4-cylinder | ||
| Mercruiser | 950 | 21-30430A1 | 6-cylinder |
Technical Specs
- Product Type
- Check Valve Kit
- Installation
- Direct replacement
- Fuel Type
- Gasoline
- Dimensions
- 11.5 cm x 11.0 cm x 2.0 cm
- Weight
- 0.03 kg (0.066 lb)
What’s in the Box
- 1 x Check Valve Kit (replaces 21-30430A1)
Installation Notes
- Before starting, disconnect the battery and carefully relieve any pressure in the fuel system.
- Locate the existing check valve on your engine's fuel system.
- Carefully disconnect the fuel lines from both sides of the old valve.
- Remove any mounting hardware and take out the old valve assembly.
- Install the new check valve from the kit, making sure it is oriented correctly according to the fuel flow direction.
- Securely reconnect the fuel lines and tighten any mounting hardware.
- Before starting the engine, reconnect the battery and prime the fuel system. Inspect for any leaks.
Troubleshooting & FAQ
How do I know if this check valve kit fits my engine?
This kit fits specific 4 and 6-cylinder Mercury and Mercruiser engines from the mid-1960s to early 1970s. The most reliable method for confirming fitment is to match your original part number to 21-30430A1 or one of the other cross-references listed. Always check the compatibility table as a second step.
What are the signs of a failing fuel check valve?
Common symptoms include hard starting, especially after the engine has been off for a while (due to fuel draining back), engine stalling at low speeds, or a general loss of power. A faulty valve can disrupt fuel pressure and flow.
What is the function of this part?
A fuel check valve is a one-way valve that allows fuel to flow from the tank to the engine but prevents it from flowing back. This ensures the fuel lines remain primed, which is essential for quick starts and consistent engine performance.
Can I use this check valve for a diesel engine?
No, this particular kit is designed and tested for use with gasoline fuel systems only. Using it with diesel or other fluids is not recommended and may cause component failure.
How often should a check valve be replaced?
There is no fixed replacement interval for a check valve. It should be inspected during regular fuel system maintenance and replaced if it shows signs of leakage, blockage, or mechanical failure.
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
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