Water Pump Cover Gasket – Fits Yanmar 1GM, 1GM10 Series (Replaces 128170-42090)
Water Pump Cover Gasket – Fits Yanmar 1GM, 1GM10 Series (Replaces 128170-42090) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
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
Water Pump Cover Gasket – Fits Yanmar 1GM, 1GM10 Series (Replaces 1...
Product Details
This aftermarket Water Pump Cover Gasket is designed for Yanmar 1-cylinder marine diesel engines from 6 to 12 HP, manufactured between 1981 and 2005. It ensures a reliable seal for the raw water pump assembly.
It serves as a direct replacement for Yanmar part number 128170-42090.
- Installs externally between the water pump cover and the main housing.
- Engineered specifically for raw water (sea water) pump applications.
- Includes one gasket, ready for installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Yanmar | 128170-42090 |
Engine & Model Compatibility
Confirm your engine model and year in the table below.
This gasket is compatible with select Yanmar 1GM series engines, known for their reliability in small marine applications.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Yanmar | 1GM | 9 | 4-Stroke | 1981–1983 | 128170-42090 |
| Yanmar | 1GM10 | 9 | 4-Stroke | 1983–2005 | 128170-42090 |
| Yanmar | 1GM10C | 9 | 4-Stroke | 1983–2005 | 128170-42090 |
| Yanmar | 1GM10L | 9 | 4-Stroke | 1983–2005 | 128170-42090 |
| Yanmar | 1GM10VE | 9 | 4-Stroke | 1983–2005 | 128170-42090 |
| Yanmar | 1GML | 9 | 4-Stroke | 1981–1983 | 128170-42090 |
| Yanmar | 1GMY-C | 9 | 4-Stroke | 1981–1983 | 128170-42090 |
Technical Specs
- Product Type
- Water Pump Cover Gasket
- Installation
- External mount, between water pump cover and housing
- Material
- Paper/Fiber Composite
- Dimensions
- 4.5" L x 4.5" W x 0.1" H
- Application
- For raw water (sea water) pump
- Warranty
- 6 months
What’s in the Box
- 1 x Sea Water Pump Impeller Gasket (Replaces 128170-42090)
Installation Notes
- Ensure the engine is off and the battery is disconnected. Close the raw water intake seacock.
- Carefully remove the screws securing the water pump cover plate.
- Remove the old cover and gasket. You may need a small pry tool if it is stuck.
- Thoroughly clean both the pump housing and cover surfaces. Ensure they are free of old gasket material, corrosion, and debris.
- Position the new gasket onto the pump housing, aligning the screw holes.
- Place the cover back on and thread the screws by hand to prevent cross-threading.
- Tighten the screws in a star pattern to ensure even pressure. Do not overtighten.
- Open the seacock, start the engine, and immediately check for any leaks around the pump cover.
Troubleshooting & FAQ
How do I know if this gasket fits my Yanmar engine?
This gasket is specifically for the Yanmar 1GM and 1GM10 series engines listed in the compatibility table. Always cross-reference your engine model and the OEM part number (128170-42090) to confirm a match.
What are the signs of a failing water pump gasket?
Common signs include visible water drips or leaks around the pump cover, especially when the engine is running. You might also notice dried salt deposits or rust stains on the pump body, indicating a slow leak.
How often should this gasket be replaced?
It is best practice to replace the water pump cover gasket every time you service the impeller, which is typically recommended annually or every 100-200 engine hours, depending on operating conditions.
Can I reuse my old gasket after inspecting the impeller?
No. Gaskets are designed for single use. They compress and deform to create a seal, and reusing an old one almost always results in leaks.
Is any sealant or gasket maker needed for installation?
Generally, no sealant is required for this type of paper gasket when installed on clean, flat surfaces. A very light film of marine grease can help hold it in place during assembly but is not necessary for sealing.
What's the difference between this and a genuine Yanmar gasket?
This is an aftermarket part designed to meet or exceed OEM specifications for fit, material, and function. It provides a cost-effective alternative to the genuine part without sacrificing performance or reliability.
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.
