water pump for DD stk metal / stewart ?

[Hornung418]

Wangan, the Plastic has been phased out by the Composite impeller.

[singh336]

plastic...nooooooooooo

[36brua]

Thanks for all the input from everyone !
interesting reading on everyone combos

[36brua]

plastic OEM BMW for DD. replace reasonably often with other cooling items (hoses, thermostat)

if car is track only or boosted up or you enjoy blowing money then the stewart is great.

I have had it and the plastic and metal oem, plastic OEM is the most engineered impeller and cannot corrode.

plastic OEM = composite ?
plastic understood
why not metal ? hard on bearings ?

I like the stewart but too much $ at the moment. too many other parts to get this put together !! LOL Thanks

[Wanganstyle]

Wangan, the Plastic has been phased out by the Composite impeller.

composite; plastic; same thing.

everything plastic made by bmw is some special composite. still plastic to me

"composite" plastic impellers for water system, plastic intake manifold "composite", "composite" plastic timing chain guides...... bmw's are made out of plastic.

even the Front wheel bearing ball retainers on OEM BMW WBS M cars (made by FAG) have are made out of "composite" or PLASTIC. These like to crumble at laguna seca

[Northern]

interesting definition of composite...

[Hornung418]

The composite is stronger and lighter than the less-expensive metal impeller version. And it does not suffer from the problems of the early plastic design. - TMS

They are completely different materials. And while you may argue that they are the same, for the sake of buying the right product, they are not.

[RobertK]

Wangan, they are not the same as the white plastic impellers used in the past.

Second, ever seen what a metal impeller can do to an aluminum timing cover when it decides to explode?

I have, lets say its easier to clean up bits of plastic from your cooling system than it is to replace your timing cover. Although the one I witnessed was on a M3 that was heavily tracked

[328ijunkie]

Graf's are junk.

[Wanganstyle]

Wangan, they are not the same as the white plastic impellers used in the past.

Second, ever seen what a metal impeller can do to an aluminum timing cover when it decides to explode?

I have, lets say its easier to clean up bits of plastic from your cooling system than it is to replace your timing cover. Although the one I witnessed was on a M3 that was heavily tracked

sorry, I have never seen the old old white plastic units - was playing with STi/evo/2jz during those days.

I have never seen one of these old white plastic (pre composite) pumps. I'm sure they are somewhere out there though and scary

never seen metal impeller pump explode either, I believe you its ugly.

[RobertK]

sorry, I have never seen the old old white plastic units - was playing with STi/evo/2jz during those days.

I have never seen one of these old white plastic (pre composite) pumps. I'm sure they are somewhere out there though and scary

never seen metal impeller pump explode either, I believe you its ugly.

I've had a few motors that still had the old plastic impeller and when I would go to pull the WP out most of the time the center would pull out leaving the impeller in the timing cover.

I was once told that the reason BMW does not use metal impellers in their cars is because of the possible damage to the timing cover (introducing water and bits of aluminum into the timing chain / oil pan).