Zinc Trim Tab Anode Mercury Mariner 30-200HP MerCruiser 31640Q4 MMS-319
mms-319
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31640-Pattern Trim Tab Zinc Anode
Aftermarket Zinc Sacrificial Anode | Reference 31640Q4
Aftermarket zinc trim-tab anode matching the long-running Mercury 31640 geometry. It provides sacrificial corrosion protection and, where used as an adjustable trim tab, can also counter steering torque. Mercury lists the 31640Q4 family for 30-200hp outboards and MerCruiser drives; exact fit still depends on the gearcase, propeller and serial-number parts diagram.
Key Features
- ✔ Sacrificial zinc corrosion protection
- ✔ Trim-tab / gearcase anode
- ✔ Aftermarket replacement geometry
- ✔ Designed to use the original mounting position
- ✔ Reference 31640Q4
Technical Specs
| Material | Zinc |
| Part type | Trim-tab / gearcase anode |
| Outer diameter | 90mm |
| Overall length / height | 105mm / 82mm |
| Fastener hole | 11.1mm (7/16in) |
| Supply type | Aftermarket replacement |
| 4Boats SKU | MMS-319 |
Compatibility / Fitment Guide
| Check | Compatible Application | Exclusion / Action |
|---|---|---|
| Mercury / Mariner | 31640Q4-family application, generally 30-200hp outboards where the parts diagram specifies this long trim tab. | High-thrust or large-diameter propellers may require a flat anode or different tab for clearance; rotate the propeller by hand after installation. |
| MerCruiser | Drives whose parts list calls for 31640-style trim tab, generally excluding Bravo. | Not a universal Bravo-drive anode. Confirm drive model and serial number. |
| Honda / OMC cross-use | Only where the exact cross-reference and dimensions match 41107-ZW1-003/003ZA or 0509460. | Do not infer compatibility with every Honda, Johnson or Evinrude outboard. |
| Physical match | Casting profile, mounting hole, seating face and clearance match the removed anode and parts diagram. | Do not order by horsepower or appearance alone; production changes can use a different anode. |
| Electrical contact | Mounting faces are clean bare metal and fastener torque follows the service manual. | Never paint, grease or electrically isolate the anode from the protected casting. |
| Alloy / water | Zinc is selected as part of a consistent anode system suitable for the vessel's operating water. | For freshwater or mixed-water use, confirm whether the manufacturer specifies aluminium or magnesium instead. |
Part Number Cross Reference
| Mercury / MerCruiser | 316404; 316406; 31640A4; 31640B4; 31640Q03; 31640Q4; 97-31640Q4; 97-31640T4; 97-31640T6; 97-8M0059338 |
| Honda / OMC | 41107-ZW1-003; 41107-ZW1-003ZA / 0509460 |
| 4Boats SKU | MMS-319 |
Cross-reference numbers identify fitment geometry. This product is aftermarket zinc and is not supplied as a genuine Mercury/Quicksilver part.
Frequently Asked Questions
Is this a genuine Mercury/Quicksilver anode?
No. It is an aftermarket zinc replacement.
Can I paint the anode?
No. Paint or sealant prevents the electrical contact and exposed surface needed for sacrificial protection.
When should it be replaced?
Inspect frequently and replace when materially wasted, cracked, loose or at the interval in the engine/drive maintenance schedule—commonly before about half the original mass is lost.
Does matching the number guarantee fit?
It is the primary check, but also compare the mounting position, dimensions, casting profile and your exact serial-number parts diagram.
Installation note: Remove corrosion from the contact face, install metal-to-metal, torque correctly and verify bonding continuity. Never use an anode as a lifting or jacking point.
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