Volvo Penta Raw Water Pump Impeller Kit 21951348 – D4 / D6 OEM

Volvo Penta Raw Water Pump Impeller Kit – Part No. 21951348

Part Number: 21951348
Brand: Volvo Penta
Supersedes: No documented earlier OEM number
Replaced By: Current – 21951348 is the active OEM number
Aftermarket Cross-References: Johnson Pump 09-812B-1, Sierra 18-3057 (verify fitment independently before substituting)

Overview

This is a genuine Volvo Penta OEM raw water pump impeller kit for D4 and D6 diesel engines and compatible V6/V8 gasoline applications. The kit includes a precision-molded flexible rubber impeller along with the pump cover gasket, O-ring/sealing components, and installation lubricant needed for a complete pump service. As an OEM kit, all components are matched to the original pump specifications for hub type, blade profile, and sealing dimensions.

Note: Part number 21951348 is a distinct OEM reference from the related Impeller Kit 21951346. Both fit D4/D6 applications but apply to different pump configurations or serial-number ranges. Confirm the correct number against your engine serial number and pump diagram before ordering.

System

Raw-Water / Seawater Cooling System – Impeller Pump. The impeller circulates seawater through the engine cooling circuit. Degraded impeller vanes reduce flow and can cause overheating or shed blade fragments into the cooling system.

Kit Contents

• 1 x flexible rubber raw water pump impeller
• Pump cover gasket
• O-ring / sealing components
• Installation lubricant

Compatible Applications

• Volvo Penta D4 series diesel engines
• Volvo Penta D6 series diesel engines
• Select Volvo Penta V6 gasoline engines with compatible raw water pump configuration
• Select Volvo Penta V8 gasoline engines with compatible raw water pump configuration
• Other Volvo Penta engines using the compatible pump assembly – confirm by engine serial number and raw water pump diagram

Serial Number & Fitment Notice

Raw water pump configurations vary across engine families, model years, and production runs. Always confirm part number 21951348 against your engine serial number and the correct Volvo Penta raw water pump diagram before ordering. Hub type and blade count are key identifiers — visually similar impellers in this range are not always interchangeable, and 21951348 is not the same kit as 21951346.

Service Interval

Replace the raw water pump impeller annually or every 100–200 hours, whichever comes first. In saltwater or high-use applications, annual replacement is strongly recommended regardless of hours. Do not wait for overheating symptoms — a degraded impeller can shed blade fragments that travel downstream and damage heat exchangers or thermostats.

When to Replace

Replace this impeller kit when the existing impeller shows cracked, missing, or hardened vanes, reduced cooling water flow at the exhaust, or any engine overheating. Also replace after extended storage where the impeller may have taken a permanent set. Replace the gasket, O-ring, and apply fresh lubricant at the same time — all are included in this kit.

Installation Notes

Apply the included lubricant to the impeller before insertion — dry installation can damage the blades immediately on first start. Install with the correct vane rotation direction for the pump. Replace all gaskets and O-rings included in the kit. Inspect the pump housing bore for scoring or wear. After reassembly, check the cooling circuit for any broken vane debris before returning the engine to service.

Technical FAQ

Q: What is the difference between 21951346 and 21951348?
A: Both are OEM Volvo Penta impeller kits for D4/D6 and compatible gasoline engines, but they apply to different pump configurations or serial-number ranges. The correct kit is determined by your engine serial number and the applicable raw water pump diagram — do not substitute one for the other without confirming fitment.

Q: Can I use the Johnson Pump 09-812B-1 or Sierra 18-3057 instead?
A: These are listed as aftermarket cross-references. Aftermarket impellers may differ in material grade or hub tolerance. Verify fitment independently against your pump assembly before substituting an aftermarket kit for the OEM.

Q: What happens if a blade breaks off?
A: Broken impeller blades travel through the cooling circuit and can lodge in heat exchangers, thermostats, or other restrictions. If you find a damaged impeller with missing blades, flush the cooling circuit and inspect downstream components before returning the engine to service.

Related Parts

• Volvo Penta Impeller Kit 21951346 – related OEM impeller kit for D4/D6 (different pump configuration)
• Volvo Penta Impeller Kit 21951352 – related OEM impeller kit in the same series
• Volvo Penta Impeller Kit 21951360 – related OEM impeller kit in the same series
• Johnson Pump 09-812B-1 Impeller Kit (F6) – aftermarket cross-reference impeller kit
• Volvo Penta Seawater Pump Cover Screw Kit 21951334 – pump cover screws for D3/D4/D6/KAD/TAMD
• Volvo Penta Seawater Pump Wear Kit 21951374 – wear components for the seawater pump family

Parts Desk Insights

This kit and 21951346 are the two most commonly confused impeller kits in the D4/D6 range — they share the same engine family and the same aftermarket cross-references, but they are not the same part. The most reliable way to confirm which kit you need is to look up your engine serial number in the Volvo Penta parts system and match the raw water pump diagram position. Ordering by engine model alone is not sufficient. Pairing this kit with the pump cover screw kit 21951334 is the cleanest way to complete the service in one pass.