Sierra Stator 18-5857 for Mercury V225 Outboard, Serial 5628028 and Up, Replaces Mercury Marine 398-5454A7

The Sierra 18-5857 is a replacement stator built for Mercury V225 outboard engines with serial number 5628028 and up. The stator is a key charging-system component mounted around the flywheel that generates AC current as the flywheel magnets pass by its windings, supplying power for ignition timing and battery charging. This unit is constructed with an aluminum housing and finished in white to match factory charging-system components, and it is rated for use in salt water applications as well as fresh water. It is designed as a direct replacement for the factory stator on applicable Mercury V225 engines, restoring proper charging output on engines where the original stator has failed, weakened, or shorted out. Because the stator sits close to the flywheel and is exposed to engine heat and marine moisture, using a properly rated replacement matched to the correct engine and serial number range is important for reliable starting and charging performance. The Sierra 18-5857 corresponds to the equivalent Mercury Marine part 398-5454A7, making it straightforward to identify against the original equipment number when sourcing a replacement. Boat owners and marine technicians use this part when diagnosing no-charge or intermittent-charge conditions, weak battery charging, or stator failure confirmed by resistance testing.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5857
• Item Type: Stator
• Material: Aluminum
• Color: White
• Weight: 3.2 pounds
• Engine Type: 4 Stroke
• Mounting Type: Transom Mount
• Fuel Type: Gasoline
• Recommended Use: For Salt Water
• UPC: 030999563835
• OEM Equivalent Part Number: Mercury Marine 398-5454A7

Fitment

• Mercury V225, serial number 5628028 and up

Replaces (OEM)

• 398-5454A7

Frequently Asked Questions

What engines does the Sierra 18-5857 stator fit? The Sierra 18-5857 is built for Mercury V225 outboard engines with serial number 5628028 and up.

Is the Sierra 18-5857 a direct replacement for the Mercury OEM stator? Yes, the 18-5857 is the equivalent replacement for Mercury Marine part 398-5454A7 and is designed to be a direct swap on applicable V225 engines.

What is the 18-5857 made of? It has an aluminum housing finished in white, matching the factory charging-system components on Mercury V225 outboards.

How much does the Sierra 18-5857 stator weigh? The Sierra 18-5857 weighs 3.2 pounds.

Can the 18-5857 be used in salt water? Yes, this stator is rated for use in salt water applications.

What does a stator do on an outboard engine? A stator is the charging-system component mounted around the flywheel that generates AC current as the flywheel magnets rotate past it, supplying power for ignition and battery charging; the Sierra 18-5857 performs this function on Mercury V225 outboards.

How do I know if my Mercury V225 needs this stator? Symptoms such as weak battery charging, no charge output, or intermittent charging combined with a failed stator resistance test on a serial-5628028-and-up V225 engine indicate the 18-5857 replacement stator is needed.

What is included when I order the 18-5857? The order includes the Sierra 18-5857 stator itself; no additional hardware is specified for this part.

Is the Sierra 18-5857 genuine Mercury or aftermarket? The 18-5857 is a Sierra-brand replacement stator manufactured to match the Mercury Marine 398-5454A7 equivalent, rather than a genuine Mercury-branded part.

Does the serial number range matter when ordering this stator? Yes, the Sierra 18-5857 is specified for Mercury V225 engines with serial number 5628028 and up, so confirming the engine serial number is important before ordering.

What UPC is associated with the Sierra 18-5857 stator? The Sierra 18-5857 stator carries UPC 030999563835.