Sierra Water Pump Base 18-3417, Replaces Mercruiser 46-57234A1, Fits MC-I & R Drives 1970-1984

The Sierra 18-3417 Water Pump Base is a precision machined replacement base for the water pump assembly on MerCruiser MC-I & R stern drives without a flush screw in the gear housing. It is built to the same fit, form, and function as the original equipment part it replaces and is intended as a direct install for units within the applicable serial number range, restoring proper water pump seating and cooling system integrity on affected drives.

This is a compact, machined component measuring 0.39 x 0.39 x 0.39 inches and weighing 0.22 pounds. It is cross-referenced to GLM 12310, Mallory 9-43306, and Mercruiser 46-57234A1, so buyers who know any of these numbers can confirm they are ordering the correct part. Every Sierra part is backed by Sierra's customer satisfaction warranty.

Important fitment note: units that have been retro-fitted with an Alpha style lower unit (no pre-load pin in the top of the driveshaft) must use Alpha style parts instead, part numbers 18-3320 or 18-3420, rather than the 18-3417.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3417
• Product Dimensions: 0.39 x 0.39 x 0.39 inches
• Weight: 0.22 pounds
• Exterior Finish: Machined
• UPC: 030999315908
• Fits: MC-I & R drives without flush screw in gear housing (1970-1984)
• Serial Number Range: 2763442 - 6854392
• OEM Cross Reference: GLM 12310, Mallory 9-43306, Mercruiser 46-57234A1

Fitment

MC-I & R drives without a flush screw in the gear housing (1970-1984), serial numbers 2763442 through 6854392. Units retro-fitted with an Alpha style lower unit (no pre-load pin in top of driveshaft) require Alpha style parts 18-3320 or 18-3420 instead.

Replaces (OEM)

• GLM 12310
• Mallory 9-43306
• Mercruiser 46-57234A1

Frequently Asked Questions

What does the Sierra 18-3417 Water Pump Base fit? The 18-3417 fits MerCruiser MC-I & R drives that do not have a flush screw in the gear housing, covering units in the serial number range 2763442 through 6854392 (1970-1984).

Is the 18-3417 interchangeable with the Mercruiser OEM part? Yes, the 18-3417 is directly interchangeable with Mercruiser OEM number 46-57234A1, as well as GLM 12310 and Mallory 9-43306.

How much does this water pump base weigh? The Sierra 18-3417 Water Pump Base weighs 0.22 pounds.

What are the dimensions of part number 18-3417? It measures 0.39 x 0.39 x 0.39 inches, a compact machined component that sits within the water pump assembly.

Will the 18-3417 fit a drive that has a flush screw in the gear housing? No. The 18-3417 is designed specifically for units without a flush screw in the gear housing; units with a flush screw use a different Sierra part number.

My drive has been retro-fitted with an Alpha style lower unit, can I still use the 18-3417? No. Units retro-fitted with an Alpha style lower unit (no pre-load pin in the top of the driveshaft) must use Alpha style parts instead, Sierra part 18-3320 or 18-3420, not the 18-3417.

What is the finish on the 18-3417 Water Pump Base? The Sierra 18-3417 has a machined exterior finish.

Does the 18-3417 come with a warranty? Yes, the Sierra 18-3417 Water Pump Base is covered under Sierra's customer satisfaction warranty like all Sierra parts.

How do I know if my serial number matches this part? The 18-3417 is designated for units without a flush screw in the gear housing falling within serial numbers 2763442 to 6854392; check your drive's serial number tag against this range before ordering.

Is the Sierra 18-3417 a genuine OEM part or aftermarket? The 18-3417 is a Sierra aftermarket water pump base engineered to meet or exceed the original equipment part it replaces, Mercruiser 46-57234A1.

What years does the 18-3417 Water Pump Base cover? This water pump base is designated for MC-I & R drives without a flush screw in the gear housing from 1970-1984.