Volvo Penta Diesel Engine Pencil Zinc Anode – Fits MD/TMD/TAMD/D Series (Replaces 838929)
This high-purity zinc pencil anode is designed to protect critical marine engine components from galvanic corrosion. It is engineered to fit a wide range of Volvo Penta marine diesel engines, including the MD40A, TMD40, D4, D6, D9, D11, TAMD60–75, TAMD103, TAMD122, TAMD162C, TAMD163 series, and 2001/2002/2003 series.
This component serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring broad compatibility for maintenance and repairs.
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Installation Method: Simple screw-in design
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Fuel Compatibility: Diesel
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Included Parts: One pencil zinc anode with plug
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand |
Part Number |
| Volvo Penta |
838929 |
| Volvo Penta |
800476 |
| Volvo Penta |
804107 |
| Volvo Penta |
858501 |
| Sierra |
18-6001 |
| Martyr |
CM838929Z |
| CAM |
838929 |
Compatible Engine Models
Confirm your engine model/year in the table below.
| Brand |
Model |
Stroke |
OEM Part No. |
Notes |
| Volvo Penta |
MD40A |
4-Stroke |
838929 |
- |
| Volvo Penta |
TMD40 |
4-Stroke |
838929 |
- |
| Volvo Penta |
D4 Series |
4-Stroke |
838929 |
- |
| Volvo Penta |
D6 Series |
4-Stroke |
838929 |
- |
| Volvo Penta |
D9 Series |
4-Stroke |
838929 |
- |
| Volvo Penta |
D11 Series |
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 Specifications
| Specification |
Value |
| 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) |
Package Contents
1 x Zinc Pencil Anode (838929)
Installation Guide
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Turn Off the Engine: Ensure the engine is completely cool and the battery is disconnected before beginning work.
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Locate the Old Anode: Find the existing pencil anode on your engine block or cooling system. It will look like a bolt or plug.
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Remove the Old Anode: Using an appropriately sized wrench, unscrew and remove the old anode plug. Be prepared for some water to drain out.
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Inspect and Clean: Clean the threads in the engine housing to remove any old sealant or corrosion.
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Install the New Anode: Screw the new pencil anode in by hand until it is snug. Finish by tightening it gently with a wrench. Do not overtighten.
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Check for Leaks: Reconnect the battery, start the engine, and check for any leaks around the new anode plug.
Troubleshooting & FAQ
Q: How do I confirm this anode fits my engine?
A: The best way is to check your engine's service manual for the correct part number. You can also compare our listed part numbers (Volvo Penta 838929, 800476, etc.) and compatible models in the tables above against your current part.
Q: What is the purpose of a zinc anode?
A: A zinc anode is a sacrificial metal that protects the vital metal components of your engine's cooling system from galvanic corrosion, which occurs when different metals are in contact in a conductive fluid like salt water.
Q: How often should I replace my engine's pencil anode?
A: Replacement intervals depend heavily on your operating conditions (salt vs. fresh water, water temperature). We recommend inspecting your anodes at least every 3-6 months. Replace the anode when it is 50% or more corroded or dissolved.
Q: What are the signs that an anode needs replacing?
A: A worn anode will be visibly pitted, crumbling, or significantly smaller than its original size. If the anode is missing entirely, it must be replaced immediately to prevent engine damage.
Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.
Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.
Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.
Important Notes
- Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
- This product is an aftermarket replacement part and is not an OEM component.
- Professional installation is recommended to ensure safety and optimal performance.
Why Choose JLM MARINE?
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Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
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Fast Global Shipping: Free delivery worldwide in 5–15 days.
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Direct from Manufacturer: Competitive pricing without compromising quality.