Sierra Water Pump Housing 18-3173-1, Replaces 61A-44311-00-00, 61A-44311-01-00

The Sierra Water Pump Housing 18-3173-1 is a replacement water pump housing for Yamaha two-stroke outboard motors. The housing is the structural body of the outboard's cooling water pump, mounting the impeller and directing raw water flow to keep the engine's cooling system operating correctly. Replacing a cracked, worn, or corroded water pump housing is a standard part of outboard lower unit water pump service and helps prevent overheating caused by a failing pump assembly.

Sierra manufactures this housing as a direct cross-reference to the original Yamaha part numbers listed below, making it a straightforward like-for-like replacement during a water pump rebuild or lower unit service. It is sold as the housing component only.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3173-1
• UPC: 808282362102
• Weight: 0.62 pounds
• Category: Yamaha Outboard Water Pumps and Impellers, Two-Stroke
• OEM Cross Reference: 61A-44311-00-00, 61A-44311-01-00
• Included Components: Water Pump Housing

Fitment

Designed for Yamaha two-stroke outboard motors.

Replaces (OEM)

• 61A-44311-00-00
• 61A-44311-01-00

Frequently Asked Questions

What is the Sierra 18-3173-1 water pump housing used for? The Sierra 18-3173-1 is a water pump housing for Yamaha two-stroke outboard motors, serving as the body that holds the impeller and directs raw cooling water through the pump assembly.

What OEM part numbers does 18-3173-1 replace? It cross-references to Yamaha OEM numbers 61A-44311-00-00 and 61A-44311-01-00, so either original number matches this Sierra housing.

Does the water pump housing include the impeller? No, the Sierra 18-3173-1 is the housing component only; the impeller and other pump service parts are sold separately.

How much does the 18-3173-1 water pump housing weigh? It weighs 0.62 pounds.

Is the Sierra 18-3173-1 a genuine Yamaha part or aftermarket? It is a Sierra-manufactured aftermarket replacement housing, built to cross-reference directly with Yamaha OEM part numbers 61A-44311-00-00 and 61A-44311-01-00.

What outboard motors is the 18-3173-1 housing compatible with? The 18-3173-1 water pump housing is designed for Yamaha two-stroke outboard motors.

Can I use 18-3173-1 to replace a cracked or corroded water pump housing? Yes, replacing a cracked or corroded housing with the Sierra 18-3173-1 is a common fix during outboard water pump service to restore proper cooling water flow.

What is included when I order part 18-3173-1? The order includes one Sierra water pump housing, part number 18-3173-1.

Is 18-3173-1 the same as Sierra part 18-3170 or 18-3171? No, 18-3170 and 18-3171 are separate Sierra water pump housing part numbers with their own distinct OEM cross-references; only 18-3173-1 replaces Yamaha 61A-44311-00-00 and 61A-44311-01-00.

Why does the water pump housing need replacing during a pump service? Over time the housing can crack, wear, or corrode from heat and water exposure, which can allow cooling water to leak or bypass the impeller; installing a Sierra 18-3173-1 housing addresses this during a full pump rebuild.