Sierra 18-3400 Water Pump Kit Without Housing for Johnson/Evinrude Outboard, Replaces 391698

The Sierra 18-3400 Water Pump Kit Without Housing is a complete rebuild kit for the water pump on Johnson/Evinrude (OMC/BRP) outboard motors. Because it is sold without a housing, it is intended for owners whose existing pump housing is still in good condition and only the wearing internals need replacement. The kit bundles every component that typically fails or wears out in service, including the impeller, wear plate, water pump cup, impeller key, grommets, oil seal, bolts, and O-rings, so a full internal rebuild can be completed in one job instead of sourcing parts individually.

At the core of the kit is the impeller (Sierra 18-3050, O.E. 386084), the part most responsible for pump output and overheating problems when it degrades. Pairing it with fresh seals, a new wear plate, and new O-rings in the same service helps restore proper cooling flow and reduces the chance of a repeat failure shortly after the impeller alone is swapped. This kit is designed to replace OEM-numbered water pump kits on applicable Johnson/Evinrude outboards.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3400
• Product Type: Water Pump Kit, Without Housing
• Application: Johnson/Evinrude (OMC/BRP) Outboard Motor
• Weight: 0.24 pounds
• UPC: 030999875594
• OEM Cross Reference: 391698, 0394711
• Kit Contents: 18-2025 Oil Seal, 18-2392 Grommet, 18-3050 Impeller (O.E. 386084), 18-3178 Wear Plate, 18-3179 Water Pump Cup, 18-3326 Impeller Key, 18-3329 Grommet, 18-3369 Bolts, 18-7116 O-Ring, 18-7139 O-Ring

Fitment

Fits Johnson/Evinrude (OMC/BRP) outboard motors that use water pump kit 391698 or 0394711.

Replaces (OEM)

• 391698
• 0394711

Frequently Asked Questions

What does the Sierra 18-3400 water pump kit include? The kit contains a full set of internal water pump components: 18-2025 oil seal, 18-2392 grommet, 18-3050 impeller, 18-3178 wear plate, 18-3179 water pump cup, 18-3326 impeller key, 18-3329 grommet, 18-3369 bolts, 18-7116 O-ring, and 18-7139 O-ring.

Does the 18-3400 kit include the pump housing? No. The Sierra 18-3400 is a water pump kit without housing, so it is meant for rebuilding a pump whose existing housing is still usable.

What OEM part numbers does the 18-3400 replace? The Sierra 18-3400 replaces OEM numbers 391698 and 0394711 on Johnson/Evinrude outboard motors.

What motors is this water pump kit designed for? This kit is built for Johnson/Evinrude (OMC/BRP) outboard motors that use water pump kit 391698 or 0394711.

Which impeller comes in the 18-3400 kit? The kit includes the Sierra 18-3050 impeller, which corresponds to OEM part number 386084.

How much does the 18-3400 water pump kit weigh? The Sierra 18-3400 weighs 0.24 pounds.

Is the Sierra 18-3400 a genuine Sierra part or a generic substitute? It is a Sierra-branded water pump kit, manufacturer part number 18-3400, engineered as a direct replacement for the listed OEM Johnson/Evinrude numbers.

Why replace more than just the impeller when rebuilding an outboard water pump? The 18-3400 kit bundles the impeller with the wear plate, water pump cup, seals, grommets, and O-rings because these parts wear alongside the impeller, and replacing them together in one job reduces the chance of a repeat pump failure.

What is the UPC for the Sierra 18-3400 water pump kit? The UPC for the Sierra 18-3400 water pump kit is 030999875594.

Can the 18-3400 be used if I am also replacing the pump housing? The 18-3400 does not include a housing, so if the housing needs replacement it must be sourced separately; this kit covers only the internal wearing components for Johnson/Evinrude outboards.

What impeller key is used in the 18-3400 kit? The kit includes impeller key 18-3326 along with the 18-3050 impeller it is paired with.

How many O-rings come in the 18-3400 kit? Two O-rings are included in the Sierra 18-3400 kit: 18-7116 and 18-7139.