UANOFCN Outboard Upper Water Pump Impeller Kit for Mercury 8-25 HP — Complete Upper Housing, Impeller & Gaskets

The UANOFCN 99157T2 is a complete upper water pump impeller repair kit designed to restore cooling flow on compatible Mercury 2- and 4-stroke outboards from 8 to 25 HP.

If your Mercury outboard is running hotter than usual or you suspect reduced water circulation, this UANOFCN kit provides the upper housing, impeller, gaskets and small parts needed to rebuild the upper section of the water pump. It replaces several Mercury part numbers and covers a range of popular 2-stroke and 4-stroke engines, making it a practical option for DIY maintenance or for marine technicians servicing small-to-mid-sized outboards.

Which Mercury engines will this kit fit?

The kit fits a variety of Mercury outboards across 2-stroke and 4-stroke families. Check the engine model and serial number to confirm compatibility before ordering, because similar engines may use different pump assemblies.

• Compatible with many 2-stroke Mercury models: 15 hp, 18 hp, 20 hp, 25 hp.
• Compatible with many 4-stroke Mercury models: 9.9 hp and 15 hp.
• Replaces OEM part numbers including 99157T2, 85098A2 and 99157A2.
• Always verify your outboard model and s/n to ensure the correct fit.

What parts are included in the repair kit?

This kit contains the essential upper pump components so you can replace worn or damaged items without sourcing multiple parts separately. The package groups the housing, seals and internal pieces you typically need for a thorough upper pump rebuild.

• Pump housing assembly and water tube guide sleeve for the upper pump section.
• Flexible rubber impeller plus face plates and plate key for proper drive alignment.
• Gaskets, O-rings, and small seals including fill and vent screw O-rings to prevent leaks.
• Additional plates and a small quantity of gear lube fill/vent screw components where required.

How will installing this kit affect engine cooling performance?

Replacing a worn impeller and related seals restores the pump’s ability to move cooling water through the engine, reducing overheating risk and improving temperature stability. Properly installed components and fresh seals also reduce the chance of external leaks.

• New impeller restores maximum water flow rate through the pump housing.
• Fresh gaskets and O-rings restore sealing integrity around the upper housing.
• Correctly timed face plates and key ensure the impeller engages and pumps efficiently.
• Prevents cavitation and loss of cooling due to degraded rubber or worn parts.

What should I check before I attempt the replacement?

Confirm your outboard’s exact model and serial number against the kit’s compatibility list and inspect the lower pump and driveshaft for damage. If the lower pump, wear plate or driveshaft are badly scored or damaged, you may need additional parts beyond this upper kit.

• Verify engine model and s/n to match Mercury part cross-references.
• Inspect the lower pump housing and water tube for scoring or corrosion.
• Check for bent or damaged driveshaft and coupling parts before reassembly.
• Have basic marine tools and a clean workspace to avoid contaminating seals during install.

Who is this for?

This UANOFCN 99157T2 upper water pump impeller kit is ideal for boat owners, marina technicians, and DIY mechanics who maintain Mercury 8–25 HP outboards and want a ready-made upper pump rebuild solution. It suits anyone who needs genuine replacement-style components to restore cooling performance quickly, provided they confirm engine compatibility and inspect related lower-pump parts before ordering.