Sierra Water Pump Impeller Repair Kit 18-3237 for MerCruiser Bravo I, II, III (1988 & Up)

The Sierra 18-3237 Impeller Repair Kit rebuilds the raw water pump on MerCruiser Bravo I, II, and III drives with a one-piece pump housing, built from serial number B664190 and up. It restores full cooling capacity to a worn or leaking pump by replacing the wear items that fail first: the impeller, the wear plate, and the sealing O-ring. Rather than replacing the entire water pump assembly, this kit lets you rebuild the existing housing at a fraction of the cost, restoring proper raw water flow to the engine's cooling system and preventing overheating caused by a cracked, glazed, or worn-down impeller.

Each kit contains a Sierra 18-3087 impeller, a Sierra 18-3350 wear plate, and a Sierra 18-7163 O-ring, giving you every wear component needed for a complete pump rebuild in a single package. The kit is built from aluminum and cast iron components to match OEM fit and durability, and is designed as a direct fit for Bravo drives with the one-piece pump housing. Because MerCruiser Bravo drives rely on a properly functioning water pump to circulate raw water through the engine, keeping this kit on hand or installing it at recommended service intervals helps prevent costly overheating damage.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3237
• Product Type: Water Pump Impeller Repair Kit
• Material: Aluminum, Cast Iron
• Weight: 0.59 pounds
• Unit Count: 1 kit
• Kit Contents: 18-3087 Impeller, 18-3350 Wear Plate, 18-7163 O-Ring
• UPC: 808282105532

Fitment

• MerCruiser Bravo I, II, III (1988 & up), Serial #B664190 & up
• Fits Bravo drives with a one-piece pump housing

Replaces (OEM)

• GLM 12084
• Mallory 9-48316

Frequently Asked Questions

What does the Sierra 18-3237 kit include? The kit contains a Sierra 18-3087 impeller, a Sierra 18-3350 wear plate, and a Sierra 18-7163 O-ring, which are the three wear components needed to rebuild the raw water pump on a compatible Bravo drive.

Which drives does part number 18-3237 fit? This kit fits MerCruiser Bravo I, II, and III drives built 1988 and up, from serial number B664190 and up, specifically drives with a one-piece pump housing.

Is 18-3237 a full water pump or a repair kit? It is a repair kit, not a complete water pump assembly. It supplies the impeller, wear plate, and O-ring used to rebuild an existing one-piece Bravo pump housing rather than replace the whole pump.

Does this kit work on a Bravo drive with a two-piece pump housing? No. The Sierra 18-3237 kit is designed specifically for Bravo drives with a one-piece pump housing; a two-piece housing requires a different kit.

What is the OEM equivalent of the 18-3237 kit? The Sierra 18-3237 kit is interchangeable with GLM 12084 and Mallory 9-48316, so any of those part numbers should get you the correct kit for a one-piece Bravo pump housing.

How much does the 18-3237 kit weigh? The Sierra 18-3237 Impeller Repair Kit weighs 0.59 pounds.

What material is the impeller in this kit made from? The components in the Sierra 18-3237 kit, including the housing-facing wear plate, are made from aluminum and cast iron to match OEM specifications.

How do I know if my Bravo drive's water pump needs this kit? Signs include engine overheating, reduced raw water flow at the tell-tale, or a cracked and glazed impeller when the pump housing is opened for inspection; the 18-3237 kit addresses all three wear items in one purchase.

Is the Sierra 18-3237 kit genuine Sierra or aftermarket? It is a genuine Sierra part, sold under Sierra part number 18-3237, and is covered by Sierra's standard customer satisfaction warranty.

Can I install the 18-3237 kit myself? Yes, the kit is designed as a drop-in rebuild for the existing one-piece Bravo pump housing, replacing the impeller, wear plate, and O-ring without needing a different pump assembly.