where are you getting you non-sense from? plastic impeller? last time they used that was in 1998. float changeing color? thats because of the coolant heat cycles. and your other post about not pushing the piston back into the caliper. Where are you getting this stuff.

i gotta educate you guys
i had no idea they stopped using plastic impeller , so why does the water pump fail , please enlighten .
i figured when the 1997 740i pump failed it was because impeller failed and that seemed to suggest that the plastic had decayed , so when i see the x5 float discolouring i add 2+2 and deduce the water pump is about to fail.
read the post on caliper again ,i said to open bleed valve to let fluid out BEFORE pushing piston in , do not push fluid back through the system , is that clear enough for you now or shall i send you back to tech training .
if bmw are training you to push fluid back through the system then they are contradicting themselves because my method is the stated bmw method , trust me .
need any more enlightenment then feel free to ask .

water pumps are driven by the engine drive belt, there is tension on this belt, and tension on the waterpump shaft. overtime, the shaft weakens, and causes the water pump shaft to wobble. Sometimes it becomes so cocked, that the water pump impeller rides against the timing case cover and stops. Other times the shaft shears off. And water pumps do not last forever, they are not designed to.

i just looked up the repair instructions for brakes for a n62 equipped x5. the only precaution is

Important!
When forcing piston back:
-
Pay attention to brake fluid level in expansion tank; brake fluid that spills over will damage paintwork.

no where does it say open the bleeder. So if you have proof of how this contradicts bmw, please show. I would like to be educated.

sounds like it is time to inspect the water pump and just fit a new pump . and i looked in literature for other time water pumps and found nothing so can you explain what else i should replace .

i looked up instructions for brakes also and what you say is correct , however , i did read instruction literature on not pushing fluid back through system and i will post as soon as i locate info .

i read somewhere to flush the system before any brake work , especially if service history incomplete , and the bmw gt1 service tool needs to be used to pulsate DSC hydraulic unit to remove any air bubbles that could be in the system due to fluid loss .

Sorry if I'm Kornfused but if it's under warranty what's with all this?
If it's bad take it in and let BMW repair it..........:dunno:

not known if the water pump or timewater pump is good or otherwise , i started this thread thinking the water pump had a plastic impeller , and after the 740i experience and having read threads on x5 world saying x5 had plastic impeller , and many failed so i thought replacing the water pump to prevent failure .

I have a 4.4 and I have read many threads about water pump failure.
The average occurrence is about 60K. Having said that IMO as long
as long as the X is under warranty there is no way I'm spending my money
based on "average occurrence" If I had a warranty I would just wait it out.

Here you go bud same motor on the 7... plenty more info on www.e38.org

http://www.bimmerboard.com/forums/posts/209627

thanks cgrosse , i already looked at those and the pics on the thorough post are very small and when magnified become pixelated and near impossible to view .

killcrap , can you elaborate on timewater pump , what is it , where is it , why and when will it fail .

typo