Advice Needed ASAP on water pump, fan clutch

[Thumbs]

I just replaced my water pump (05/01 3.0i, manual trans) and it had a factory metal impellor. The replacement pump also had a metal impellor but it was of SIGNIFICANTLY lower quality. The original was (appeared to be) stainless steel, thin stuff that was stamped and welded. Nice and shiny, smooth surfaces, light weight (easy to rotate a lighter mass). The replacement was a hunk of cast metal with polished exterior but all of the interior channels were rough sand cast and the impellor must weight 5-10 times as much as the factory piece.

I don't know if it will affect performance, but I would think the rough surface and extra mass would be bad.

[Harley Monster]

I put in the Stewart pump and it appeared to be of high quality. My 2001 X5 3.0L original pump also had the metal impeller.

I would not worry about roughness in the impeller, though it would probably be more efficient if it was smooth these pumps are not exactly high tech. Pumps like yours are probably keeping thousands of BMW's cool. I don't believe the X5 normally has overheating problems, it is a well designed cooling system.