05-24-2010, 04:00 PM
Join Date: Jan 2006
My Ride: ESS TS2 320ci
| Pumps with plastic impeller:
Discontinued because of impeller shattering
Pumps with spot welded impeller:
Seen cases where impeller came apart, you don't want metal pieces inside the engine block.
Pumps with composite impeller (Current OEM):
Impeller seems to last but can't say the same for the bearing which likes to die at random mileage. If you have a mechanical fan connected to it be ready to have blades flying all over under the hood. OEM pumps also like to leak from the rubber gasket sometimes (and pls, it's torqued properly).
Having investigated all the available options (when my pump bearing failed) I chose to get the Stewart one. At least now I know that there's one thing less to break in my car.
So, IMHO the best replacement water pump for the E46 is the Stewart. If it's not an option, get the OEM and monitor it every once in a while