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Water Pump Impeller Kit – Fits Volvo Penta 5.7 GSi I/O (Replaces 21951348)

Regular price $0.00
Shipping calculated at checkout.

Water Pump Impeller Kit – Fits Volvo Penta 5.7 GSi I/O (Replaces 21951348) 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 Water Pump Impeller Kit is designed for marine inboard/outboard engines, specifically fitting the Volvo Penta 5.7 GSi I/O (4-Stroke) models. It ensures your engine’s cooling system operates efficiently by replacing a worn or damaged impeller.

The kit serves as a direct interchange for Volvo Penta part number 21951348 and Sierra 18-3081.

  • Engineered for direct replacement installation.
  • Includes essential components like the O-ring, rubber stop lug, and impeller lubricant for a complete service.
  • Restores cooling system performance to prevent overheating.

Part Number Matrix

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

Brand Part Number
Volvo Penta 21951348
Sierra 18-3081

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This kit is verified for the following Volvo Penta engine models.

Brand Model Stroke OEM Part No.
Volvo Penta 5.7 GSi I/O 4-Stroke 21951348

Technical Specs

Product Type
Water Pump Impeller Kit
Installation
Direct replacement
Dimensions
16.0" L x 10.0" W x 3.0" H
Other Technical Attributes
Includes rubber stop lug

What’s in the Box

  • 1 x Water Pump Impeller (21951348)
  • 1 x O-ring
  • 1 x Impeller Lubricant
  • 1 x Rubber Stop Lug (3857954)

Installation Notes

  1. Disconnect the battery and close the engine's water inlet valve (seacock).
  2. Locate the sea water pump housing on the engine.
  3. Place a towel or container underneath to catch any residual water.
  4. Remove the screws securing the pump cover.
  5. Carefully pry off the cover. Note the orientation of the old impeller's blades.
  6. Remove the old impeller using pliers or an impeller puller tool.
  7. Clean the inside of the housing and the cover plate, ensuring sealing surfaces are clear of debris.
  8. Apply the included lubricant to the inside of the housing and to the new impeller.
  9. Install the new impeller with the blades oriented in the same direction as the old one.
  10. Replace the O-ring and reinstall the cover plate, tightening screws evenly.
  11. Open the seacock and reconnect the battery.
  12. Start the engine and immediately check for proper water flow from the exhaust and look for any leaks at the pump housing.

Troubleshooting & FAQ

How do I know if this impeller kit fits my engine?

This kit is specifically for the Volvo Penta 5.7 GSi I/O engine. Always verify your engine model and cross-reference the OEM part number (21951348) listed in our compatibility tables before purchasing.

What are the signs of a failing water pump impeller?

Common symptoms include the engine running hotter than normal, a "high temperature" alarm, or a noticeable reduction in water flowing from the exhaust outlet. A visual inspection may reveal cracked, brittle, or missing impeller blades.

How often should I replace my engine's impeller?

As a general maintenance rule, it is recommended to inspect your impeller annually and replace it every 1 to 2 years (or every 100-200 service hours), regardless of its appearance. Impellers can become stiff and less effective over time even without visible damage.

What is the purpose of the included impeller lubricant?

The lubricant is a specialized glycerin-based compound applied during installation. It protects the new impeller from damage during the first few seconds of engine start-up before water reaches the sea water pump.

Do I need special tools for installation?

While basic hand tools (wrenches, screwdrivers) are sufficient for many, an impeller puller tool can make removing the old impeller much easier, especially if it is stuck. Gasket sealant may also be needed for some pump models.

Why does the kit include a rubber stop lug?

The rubber stop lug (part 3857954) is a specific component for certain Volvo Penta sea water pump models. It acts as a stop or cushion within the pump assembly to ensure correct alignment and function.

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.

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