M20 Water Pumps
From E30 Zone Wiki
There are two types of water pump for the M20 engine and it is essential to get the correct one for your engine.
The pump for the high compression engine (as found in pre-facelift/metal bumbered E30's) has two outlets for hoses, wheras the pump for the low compression engine (as found in facelift/plastic bumpered E30's) only has one.
Both types of water pump are available from a number of different manufacturers and vary in quality, the better quality pumps have a metal impeller (rather than plastic), these are generally considered to be the one's to go for.
