View single post by Esprit2
 Posted: 09-23-2019 03:00 am
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Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 458
See the attached JPEG. Note that both the 907 impeller on the left, and the 910 impeller on the right have backward curved vanes (the impeller rotates clockwise). Early 907 impellers had forward curved vanes, which caused cavitation at higher rpm, and led to over-heating.

Whenever you rebuild an early 907 pump, make note of the vane's direction of curvature. If they curve forward, then replace it wil a later impeller. Either a later one meant for your pump (small vanes), or a 910 impeller with the longer vanes.

At some point in time, Lotus metricated the water pump. The impellers are available with both 1/2" and 12mm ID bores, and the bearing shafts & seals are available with matching diameters. Either inch or metric can be used equally well in your early, inch pump housing, as long as you specify the bearing and seal with matching diameters. Buy in 'sets'.

Tim Engel

Attachment: Cooling - Water Pump - Impeller - 907 left & 910 right - high 94kb.jpg (Downloaded 145 times)

Last edited on 09-23-2019 03:06 am by Esprit2