Water Pump Impeller Kit 47-89981Q1 for Mercury 4 4.5 6 7.5 9.8 HP Outboard

Product Overview

Water pump impeller kit part for Mercury 4 HP, 4.5 HP, 6 HP, 7.5 HP and 9.8 HP outboards, replacing 47-89981Q1, 89981T2 and 89981Q1 and crossing to Sierra 18-3239. The impeller insert measures 0.456 inch (11.6 mm), and the kit is supplied as 1 x impeller, 1 x face plate, 1 x drive key, 1 x water guide tube and 3 x O-rings.

This is a service kit rather than an impeller on its own, because on the small Mercury pump the face plate wears with the blades. A new impeller against a scored face plate loses pressure straight away, so the plate comes in the box with the key, the guide tube and the three O-rings that seal the housing.

The kit covers the four, six and seven and a half horsepower single and twin cylinder motors, plus the 9.8 HP badged as the 110, from the 1970s through the serial ranges in the table below. Mercury built these pumps for two decades without changing the insert diameter, which is why one kit covers 4 HP to 9.8 HP.

Specifications & Attributes

OEM Cross Reference

Compatible Engines

What's Included

Condition & Warranty

Before You Buy

• Check the impeller insert is 0.456 inch, the larger Mercury pump uses a bigger shaft
• Check the serial number against the table, the 6 HP was built in several overlapping ranges
• Fit the new face plate in the kit, reusing the old one wastes most of the new impeller's pressure
• Check the pump housing liner for deep grooves, a scored housing needs replacing as well
• Lubricate the impeller with glycerine and turn the shaft by hand to set the blade direction
• Check the telltale at idle and again at planing speed on the first run
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