Sierra Impeller 18-8926, Replaces 20300, For GM Engines with V-Belt Water Pumps

The Sierra Impeller 18-8926 is a replacement water pump impeller engineered for GM engines equipped with V-belt driven water pumps. As the impeller wears, spins loose in its housing, or loses vane flexibility, cooling water flow drops and engine temperatures rise, so keeping a correctly sized replacement on hand is a routine part of marine engine maintenance. The 18-8926 is molded from plastic for consistent vane geometry and directly replaces OEM part number 20300, making it a straightforward drop-in swap during routine water pump service or a rebuild.

Sierra impellers are manufactured to match OEM sizing and vane profile so the replacement seats and seals correctly in the original pump housing without modification. Because raw water impellers are a wear item, most engine builders recommend replacing the impeller on a set service interval or any time the water pump is opened for inspection, rather than waiting for a failure at the dock.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-8926
• Material: Plastic
• Weight: 0.38 pounds
• Unit Count: 1
• UPC: 808282316013
• GTIN: 00808282316013
• Replaces (OEM): 20300
• Fitment: GM engines with V-belt driven water pumps

Fitment

• GM engines with V-belt driven water pumps

Replaces (OEM)

• 20300

Frequently Asked Questions

What does the Sierra 18-8926 impeller replace? The Sierra 18-8926 directly replaces OEM part number 20300, so it is a straight cross-reference swap for that original impeller.

What engines is the 18-8926 impeller designed for? It is designed for GM engines equipped with V-belt driven water pumps.

What material is the 18-8926 impeller made from? It is molded from plastic, formulated for durability and consistent vane flexibility in raw water cooling service.

How much does the 18-8926 impeller weigh? The Sierra 18-8926 impeller weighs 0.38 pounds.

How many impellers come in the package? The 18-8926 is sold as a single unit, one impeller per package.

Is the Sierra 18-8926 an OEM part or an aftermarket replacement? It is an aftermarket replacement impeller manufactured by Sierra to replace OEM number 20300.

When should I replace the impeller on a GM V-belt water pump? Impellers are a wear item, so the 18-8926 should be installed any time the vanes show cracking, chunking, or loss of flexibility, or as part of routine water pump service.

Will the 18-8926 fit a serpentine belt driven water pump? The 18-8926 is specified for GM engines with V-belt driven water pumps, not serpentine belt applications.

What is the UPC for the Sierra 18-8926 impeller? The UPC for the Sierra 18-8926 impeller is 808282316013.

Does the 18-8926 impeller include a gasket or housing? The 18-8926 is the impeller only; it does not include a pump gasket or housing.