Sierra 18-3109 Water Tube Guide for Mercury Outboard Cooling Systems, White Plastic

The Sierra 18-3109 Water Tube Guide is a replacement component for the Mercury outboard cooling system, engineered to direct water flow through the tube passage that feeds the engine's cooling circuit. It is molded from durable white plastic, giving it corrosion resistance in the wet, salt-exposed environment around an outboard's lower cooling components, unlike a metal guide that would be prone to rust or galvanic corrosion over time.

This water tube guide is a small but important part of the cooling system: if it wears, cracks, or goes missing, the water tube can lose proper alignment and reduce the amount of raw water reaching the engine, which can lead to overheating. Replacing a worn or damaged guide with the correct Sierra 18-3109 part restores proper tube seating and cooling flow. Sierra manufactures this part to meet or exceed the specifications of the original equipment it replaces, so it installs and functions as a direct equivalent.

The 18-3109 is cross-referenced to the GLM 12820 water tube guide as well as Mallory 9-45623 and several Mercruiser/Mercury part numbers, making it a straightforward swap for owners replacing a worn factory guide on compatible Mercury outboard cooling systems.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3109
• Product Name: Water Tube Guide
• Category: Mercury Outboard Cooling System
• Material: Plastic
• Color: White
• Weight: 0.02 pounds
• Package Dimensions: 3.048 centimeters H x 8.89 centimeters L x 5.08 centimeters W
• UPC: 030999315465
• Country of Origin: United States

Fitment

Fits the Mercury outboard cooling system as a replacement water tube guide.

Replaces (OEM)

• GLM 12820
• Mallory 9-45623
• Mercruiser/Mercury 23-52928
• Mercruiser/Mercury 23-29804
• Mercruiser/Mercury 23-29804T

Frequently Asked Questions

What is the Sierra 18-3109 used for? It is a water tube guide for the Mercury outboard cooling system, positioning the water tube so raw water flows correctly into the engine's cooling circuit.

Is the Sierra 18-3109 a genuine Sierra part or aftermarket? The 18-3109 is manufactured by Sierra as a direct replacement part, built to meet or exceed the specifications of the original equipment component it replaces.

What OEM and cross-reference numbers does the 18-3109 replace? The Sierra 18-3109 cross-references to GLM 12820, Mallory 9-45623, and Mercruiser/Mercury numbers 23-52928, 23-29804, and 23-29804T.

What material is the water tube guide made of? The Sierra 18-3109 Water Tube Guide is made of white plastic, which resists corrosion in the wet environment around an outboard's cooling components.

How much does the 18-3109 weigh? The Sierra 18-3109 Water Tube Guide weighs 0.02 pounds.

What color is the Sierra 18-3109 water tube guide? This water tube guide is white.

What are the package dimensions of the 18-3109? The Sierra 18-3109 ships in a package measuring 3.048 centimeters high by 8.89 centimeters long by 5.08 centimeters wide.

Will the GLM 12820 fit in place of the Sierra 18-3109? Yes, the GLM 12820 is cross-referenced to the Sierra 18-3109 as an equivalent water tube guide.

What does a worn water tube guide cause if not replaced? A worn or cracked water tube guide, like the one the Sierra 18-3109 replaces, can allow the water tube to misalign and reduce raw water flow to the engine, contributing to overheating.

What is included when you order the 18-3109? The order includes one Sierra 18-3109 Water Tube Guide.

Is the Sierra 18-3109 only for Mercury outboards? The 18-3109 is categorized for the Mercury outboard cooling system and is cross-referenced to Mercruiser/Mercury OEM numbers.