Impellers play a key role in keeping boat engines cool. Malfunctions can lead to engine overheating. In addition to spoiling what would otherwise have been a fun day on the water, that can lead to costly tows and even more expensive engine repairs or replacements. Experts recommend that impellers be changed at least annually to avoid problems. If you use your boat hard, you may want to change your impeller more often. If you are looking for an Indmar water pump impeller, the Johnson 09-812 BT Impeller Service Kit from SWELL fits most Indmar marine engines. Johnson 09-812B-1 Description: This is an OEM replacement Impeller service kit for almost all Indmar engine makes and models. It fits in all Malibu Boats with an Indmar engine from 1996 to current production. It also fits engines equipped with the Johnson F6B raw water pump, including Axis Wake and Volvo Penta. SPX's Johnson Pump brand impellers are OEM Replacements and developed and manufactured for maximum flow and long life. With this impeller, you can also be sure you are getting the quality required by engine manufacturers and professionals. It is manufacturer-recommended to service your impeller annually or every 100 hours of operation.