Marinepro Outboard Water Pump Impeller Kit for Mercury/Mariner 8–25 HP — Complete Housing, Impeller & Seals

Marinepro 99157T2 is a complete outboard water pump impeller kit engineered to replace Mercury/Mariner parts and restore proper cooling flow on 8–25 HP 2‑ and 4‑stroke outboards.

This kit bundles the critical components needed to service the lower unit cooling system on a wide range of Mercury and Mariner small outboards. It replaces several OEM numbers (including 46‑99157T2, 99157A2 and 85098A2) and fits many 2‑stroke 15–25 HP models and 4‑stroke 8–15 HP/9.9–13.5 HP configurations, including specific BigFoot engines. The set arrives with the housing, impeller, gaskets, hardware and seals so you can complete a full water pump job without hunting individual parts.

Which Mercury and Mariner engines will this impeller kit fit?

This kit is made to match OEM profiles for a variety of small outboards. Confirm fitment by cross‑referencing your engine serial numbers and model year ranges; the kit explicitly covers many 2‑ and 4‑stroke 8–25 HP variants and BigFoot 9.9/15 HP 4‑stroke ranges listed by serial blocks.

• Replaces Mercury numbers: 46‑99157T2, 4699157T2, 99157T2, 46‑99157A2, 46‑85098A2, 4699157A2, 4685098A2, 99157A2, 85098A2.
• Also replaces GLM part 12014 for cross compatibility.
• Fits 2‑stroke 15, 18, 20, 25 HP and 4‑stroke 8, 9.9, 13.5, 15 HP engines noted in specifications.
• Specifically lists Mercury 9.9 HP and 15 HP BigFoot 4‑stroke models within given serial ranges.

What components are included and why they matter?

The kit contains every service item required to rebuild the pump assembly so you can replace worn parts in one visit. Having the correct housing, impeller and sealing parts prevents leaks, improves cooling flow, and reduces the chance of repeat failures from missing hardware.

• 1 pump housing assembly — mounts and locates the impeller.
• 1 molded rubber impeller — flexible vanes move coolant through the block.
• Gasket and face plate — ensure a water‑tight seal at the housing joint.
• Drive key, seal, washers, grommets and rings — all hardware to secure and seal the assembly.

How do I install this kit and what should I watch for?

Installation is a routine mechanical task for anyone familiar with lower unit service; follow the engine manufacturer’s procedures and torque specs. Inspect the impeller for correct vane direction, lubricate as instructed, replace all seals, and test for proper water flow at idle before heading out.

• Follow Mercury/Mariner torque and reassembly sequences in the service manual.
• Orient impeller vanes correctly and use appropriate lube during assembly.
• Replace all gaskets and seals rather than reusing old components.
• Bench‑test water flow or run engine briefly in a test tank to confirm cooling.

Who is this for: Marinepro’s 99157T2 impeller kit is aimed at boat owners, marine mechanics, and service shops maintaining small Mercury and Mariner outboards where OEM‑equivalent replacement parts are required. Choose this kit if you need a complete water pump rebuild package that matches common OEM numbers, covers popular 8–25 HP models (including specified BigFoot 4‑stroke ranges), and includes the seals and hardware necessary for reliable reassembly. If you’re unsure about fitment, have your engine model and serial numbers on hand before ordering or consult a certified technician.