Sierra 18-3017 Impeller - Replaces Mercury Marine 47-89984, 47-30221 - MerCruiser MR/Alpha One Stern Drives

The Sierra 18-3017 is a replacement water pump impeller engineered for MerCruiser MR and Alpha One stern drives. As the wear component inside the drive's water pump, the impeller circulates raw water through the cooling system, and its flexible vanes are the first part to degrade from age, dry-running, or debris intake, which makes periodic replacement essential to prevent overheating. This impeller cross-references directly to Mercury Marine, MerCruiser stern drive, and Chrysler/Force OEM part numbers, giving boat owners and marine technicians a straightforward way to source a correct replacement without going through the original engine manufacturer. It is built with a machined exterior for a consistent fit inside the pump housing and is sized for the pump body used on MR and Alpha One drives within specific serial number ranges. The 18-3017 is also the impeller specified for use inside a number of Sierra water pump kits and a complete lower gearcase rebuild kit, so it can be purchased on its own for a straight impeller swap or as part of a broader water pump service. At 0.2 pounds and approximately 1.5 x 6 x 6 inches as packaged, it is a compact, low-cost part that keeps a stern drive's raw water cooling system running as designed. Because fitment is tied to drive serial number, confirming the correct range before ordering helps ensure the right impeller is installed the first time.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3017
• Product Type: Impeller
• Weight: 0.2 pounds
• Dimensions: 1.5 x 6 x 6 inches
• Exterior: Machined
• UPC: 030999315045
• Compatible Sierra Kits: 18-3217, 18-3217D, 18-3251, 18-3251D, 18-3314, 18-3316, 18-3317, 18-3319, 18-3320, 18-3321, 18-3517, 18-8370
• OEM Cross-Reference Numbers: 47-65960, 47-803631T, 47-89984, 47-89984T4, 694065, 47-F694065, 47-30221, 89840, 9-45306, 47-899844, 47-899842, 47-85460, 47-89984T3

Fitment

• MerCruiser MR and Alpha One stern drives, serial numbers 2495186 to 2763441
• MerCruiser MR and Alpha One stern drives without a flush screw in the gear housing, serial numbers 2763442 to 6854392
• MerCruiser MR/Alpha One stern drives, serial numbers 6854393 to 0D594568

Units in the 2763442 to 6854392 serial range that have been retro-fitted with an Alpha-style lower unit (no pre-load pin in the top of the driveshaft) require Alpha-style parts instead, and should use part numbers 18-3320 and 18-3420 rather than the standard parts listed for that range.

Replaces (OEM)

• 47-65960
• 47-803631T
• 47-89984
• 47-89984T4
• 694065
• 47-F694065
• 47-30221
• 89840
• 9-45306
• 47-899844
• 47-899842
• 47-85460
• 47-89984T3

Frequently Asked Questions

What does the Sierra 18-3017 impeller fit? The Sierra 18-3017 fits MerCruiser MR and Alpha One stern drives, and the correct application depends on the drive's serial number: 2495186 to 2763441, 2763442 to 6854392 (units without a flush screw in the gear housing), or 6854393 to 0D594568.

Is the 18-3017 a genuine Sierra part or an aftermarket copy? Part number 18-3017 is a Sierra-brand impeller sold under that number, made to cross-reference directly with the original Mercury Marine and MerCruiser impellers it replaces.

Which OEM part numbers does 18-3017 replace? The 18-3017 cross-references to Mercury Marine and MerCruiser numbers 47-65960, 47-89984, 47-89984T4, 47-89984T3, 47-899842, 47-899844, 47-85460, 47-30221, and 694065, as well as Chrysler/Force numbers 47-803631T and 47-F694065.

How much does this impeller weigh? The Sierra 18-3017 impeller weighs 0.2 pounds.

What are the dimensions of the 18-3017? As packaged, the Sierra 18-3017 measures approximately 1.5 x 6 x 6 inches.

Can I use 18-3017 if my drive has been retrofitted with an Alpha-style lower unit? No, not for units in the 2763442 to 6854392 serial range: if that drive has been retro-fitted with an Alpha-style lower unit (no pre-load pin in the top of the driveshaft), it needs Alpha-style parts 18-3320 and 18-3420 instead of the standard impeller listed for that range.

What finish does the 18-3017 impeller have? The Sierra 18-3017 has a machined exterior finish.

Is 18-3017 used in any complete water pump kits? Yes, the 18-3017 impeller is specified for use inside several Sierra water pump kits, including 18-3217, 18-3251, 18-3314, 18-3316, 18-3317, 18-3319, 18-3320, 18-3321, 18-3517, and the 18-8370 complete lower gearcase rebuild kit.

How do I know if 18-3017 is the right impeller for my MerCruiser instead of a different Sierra number? Fitment for 18-3017 is tied to your MerCruiser MR or Alpha One drive's serial number falling within 2495186 to 6854392 (or up to 0D594568 for MR/Alpha One units); drives outside these ranges, such as Alpha One Generation II, Vazer, or Bravo units, use a different impeller part number.

Does the 18-3017 include the water pump housing or gasket? The 18-3017 is the impeller itself; it is designed to install into the existing MerCruiser MR/Alpha One water pump housing rather than including a housing or full gasket set.

Will 18-3017 fit a Chrysler or Force outboard? The 18-3017 cross-references to Chrysler/Force part numbers 47-803631T and 47-F694065, indicating compatibility with certain Chrysler/Force applications that use those OEM impellers.