Volvo Penta 21868042 Aluminum Anode Kit D4 D6 DPH DPR DPI Internal Cooling

Volvo Penta 21868042 is a genuine OEM aluminum anode kit designed to protect D4 and D6 engines paired with DPH, DPR, and DPI drives from galvanic corrosion. This kit installs within the cooling and exhaust system, where it sacrificially corrodes to protect internal components such as heat exchangers and exhaust passages. Aluminum construction provides longer service life and broader protection than zinc, making it the preferred choice for saltwater and brackish water applications.

Part Information

• Part Number: 21868042
• Brand: Volvo Penta
• Official Product Type: Aluminum Anode Kit Internal Cooling System (OEM)
• Supersedes: 21718129
• Replaced By: 21868042 is the current active OEM number
• System: Internal Cooling / Exhaust Galvanic Corrosion Protection
• Kit Contents: Aluminum sacrificial anode(s) and sealing O-rings

Dimensions & Specifications

• Weight: ~1.0 kg (kit)
• Material: Aluminum (sacrificial anode)
• Fit Type: OEM direct replacement
• Anode Type: Internal cooling/exhaust housing

Compatible Applications

• Volvo Penta D4 engine with DPH sterndrive
• Volvo Penta D4 engine with DPR sterndrive
• Volvo Penta D4 engine with DPI drive
• Volvo Penta D6 engine with DPH sterndrive
• Volvo Penta D6 engine with DPR sterndrive
• Volvo Penta D6 engine with DPI drive

Fitment can vary by engine version, cooling system configuration, and production range. Always confirm part number 21868042 against your exact engine model and serial number before ordering.

Service Interval

Inspect the anode annually or more frequently in saltwater or high-use applications. Replace when the anode is 50% consumed or more, during any cooling system service, or when there is evidence of corrosion or blockage in the cooling passages. Do not allow the anode to fully deplete before replacement.

When to Replace

• Anode is 50% consumed or more
• Scheduled cooling system service
• Evidence of corrosion or blockage in cooling passages
• Annual inspection (recommended for saltwater use)

Installation Notes

• Install in the designated cooling/exhaust housing per the Volvo Penta service diagram
• Replace the included O-rings during every service do not reuse old O-rings
• Ensure proper sealing and correct torque on all fittings
• Do not paint anodes paint prevents the sacrificial reaction and renders the anode ineffective
• Inspect periodically for wear between annual services in high-salinity environments

Alternate & Superseded Part Numbers

• 21868042 Current active Volvo Penta OEM part number
• 21718129 Previous Volvo Penta number, superseded by 21868042

Parts Desk Insights

Internal anodes are one of the most overlooked service items on diesel sterndrive packages most owners focus on external anodes and miss this one entirely until corrosion damage shows up inside the heat exchanger or exhaust housing. The most common issue we see is customers waiting until the anode is fully depleted, which can allow corrosion to progress inside the engine before the next service. This kit is best suited for annual cooling system service on D4 and D6 diesel sterndrive packages operating in saltwater or mixed-water environments. Aluminum is the correct choice here zinc anodes are not recommended for internal cooling system use on these engines.