Pencil Zinc Anode – Fits Volvo Penta MD/TMD/TAMD/D Series (Replaces 838929, 800476, 804107, 858501, 18-6001)
Pencil Zinc Anode – Fits Volvo Penta MD/TMD/TAMD/D Series (Replaces 838929, 800476, 804107, 858501, 18-6001) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Pencil Zinc Anode – Fits Volvo Penta MD/TMD/TAMD/D Series (Replaces 838929, 800476, 804107, 858501, 18-6001) is backordered and will ship as soon as it is back in stock.
Product Details
This Volvo Penta Diesel Engine Pencil Zinc Anode is designed to protect a wide array of Volvo Penta marine diesel engines from galvanic corrosion. It is specifically engineered for fitment in MD, TMD, TAMD, D series (including D4, D6, D9, D11), and 2001/2002/2003 series engines, providing essential protection in saltwater environments.
This anode serves as a direct interchange for Volvo Penta part numbers 838929, 800476, 804107, and 858501. It is also a cross-reference for Sierra 18-6001, Martyr CM838929Z, and CAM838929.
- Installation: Screw-in type with a 7/16" UNC male thread.
- Material: High-purity zinc alloy that meets MIL-Spec 18001-J for sacrificial anodes.
- Package Contents: Includes one pencil zinc anode with integrated plug.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Volvo Penta | 838929 |
| Volvo Penta | 800476 |
| Volvo Penta | 804107 |
| Volvo Penta | 858501 |
| Sierra | 18-6001 |
| Martyr | CM838929Z |
| CAM | CAM838929 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Volvo Penta | MD40A | 4-Stroke | 838929 | |||
| Volvo Penta | TMD40 | 4-Stroke | 838929 | |||
| Volvo Penta | D4 Series | 210-320 | 4-Stroke | 838929 | ||
| Volvo Penta | D6 Series | 330-400 | 4-Stroke | 838929 | ||
| Volvo Penta | D9 Series | 425-575 | 4-Stroke | 838929 | ||
| Volvo Penta | D11 Series | 625-725 | 4-Stroke | 838929 | ||
| Volvo Penta | TAMD60 | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD63 | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD70 | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD74 | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD75 | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD103 | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD122A | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD122P | 4-Stroke | 838929 | |||
| Volvo Penta | D12C | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD162C | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD163A-A | 4-Stroke | 838929 | |||
| Volvo Penta | TAMD163P-A | 4-Stroke | 838929 | |||
| Volvo Penta | 2001 Series | 4-Stroke | 838929 | For salt water cooled versions | ||
| Volvo Penta | 2002 Series | 4-Stroke | 838929 | For salt water cooled versions | ||
| Volvo Penta | 2003 Series | 4-Stroke | 838929 | For salt water cooled versions | ||
| Volvo Penta | AQAD30A | 4-Stroke | 838929 | |||
| Volvo Penta | AQAD31A | 4-Stroke | 838929 | |||
| Volvo Penta | AD31A/B/D/XD/P/L | 4-Stroke | 838929 |
Technical Specs
- Product Type
- Pencil Zinc Anode
- Installation
- Screw-in
- Fuel Type
- Diesel
- Connection
- Male thread 7/16" UNC with M8 internal thread
- Housing Material
- High-purity zinc alloy
- Housing Color
- Metallic zinc
- Dimensions
- 45mm length × 14mm diameter (1-3/4" × 9/16")
- Weight
- 0.045 kg (0.10 lbs)
- Thread Size
- 7/16" UNC external, M8 internal
- Operating Temperature
- -30°C to 60°C (-22°F to 140°F)
- Other Technical Attributes
- Meets MIL Spec 18001-J (Military specification for sacrificial zinc anodes)
What’s in the Box
- 1 x Zinc Pencil Anode (838929)
Installation Notes
- Ensure the engine is off and cool, and close the relevant seacock to stop water flow.
- Place a suitable container below the anode plug to collect any draining coolant or water.
- Use a wrench to carefully unscrew and remove the old anode plug assembly.
- Inspect the old anode for its rate of wear and compare the new anode to ensure it is a correct match.
- Clean the threads in the engine housing before installing the new anode.
- Install the new pencil anode, screwing it in by hand first to prevent cross-threading.
- Tighten the plug securely with a wrench, but do not overtighten.
- Open the seacock, start the engine, and carefully check the area for any leaks.
Troubleshooting & FAQ
How often should this anode be replaced?
Replacement frequency depends on your boat's operating environment (especially water salinity and temperature) and usage hours. A general best practice is to inspect anodes every 3-6 months and replace them when they are approximately 50% consumed.
What are the signs a pencil anode is failing or needs to be replaced?
Visual inspection is key. Look for signs of crumbling, significant pitting, or a reduction in size. If the anode pencil is completely gone or only the threaded plug remains, it is past due for replacement, and your engine components have been unprotected.
Will this fit my specific Volvo Penta D6-370?
Yes, this pencil anode is specified for the entire Volvo Penta D6 series. However, always double-check against the part number (838929) listed in your engine's service manual to guarantee a perfect match.
What is the difference between zinc and aluminum anodes?
Zinc anodes, like this one, are specifically formulated for use in saltwater. Aluminum anodes are generally used for brackish water environments. Never use magnesium anodes in salt or brackish water, as they will corrode too quickly.
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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