Type of replacement waterpump

[pina4greg]

Just trying to get a sample of the types of water pump that have been replaced in the z3.
i have found that there are the originals with plastic impellers, ones with composite impellers and then the metal ones.

can you tell me your experiences regarding price and quality and improvement<

 

[GazHyde]

When I changed my I bought a metal impeller version from my local motor factors, but that decision was purely on cost at the time. If I could have afforded it I would have probably gone with a Stewart pump on reputation.

As for quality, it's been in there several thousand miles and hasn't broken yet!

 

[Cooper]

There are quite a few posts on this. The consencious seems to be the Stewart but if you cant get that then get one with a metal impeller. Please excuse spelling mistakes i am on the Tab!

There are a lot of dif experiences with some people changing out their plastic impeller pumps with no damage whatsoever! Others have had failures and wish they had a Stewart, and usually get one!

Hope that helps.

 

[jonco]

Stewart's are good but expensive. I fitted a Meyle (metal impeller) - good quality and mid range price.

 

[tower]

Stewart's are good but expensive. I fitted a Meyle (metal impeller) - good quality and mid range price.

have just finished renovating the cooling system ,water pump was a Kohle Schmidt (metal impeller) oem replacement from c3bmw

 

[vintage42]

Most Z3s were given solid composite plastic impellers, probably a good compromise of cost and light weight and durability.
Metal impellers can be either solid or sheet. The solid metal Stewart or Geba impeller is a replacement upgrade, does not come apart, but their weight can shorten the life of the pump bearing.
Here's a video showing a Graf pump with an impeller made of sheet metal that is spot-welded:

View: https://www.youtube.com/watch?v=eeFUhg8PmDk

They can come apart.
http://www.m3forum.net/m3forum/showthread.php?t=338159

 

[oldcarman]

Seems to me that the unevenness would put undue stress on those few spot welds and uneven pressure on the bearings, from the waterpump in the video. Kind of scary that all that fragmented metal could get circulating in the engine. JIM

 

[vintage42]

Seems to me that the unevenness would put undue stress on those few spot welds and uneven pressure on the bearings, from the waterpump in the video. Kind of scary that all that fragmented metal could get circulating in the engine. JIM

At least it's in the cooling system, not the lubrication system.