[JFP in PA]

Originally Posted by Bigsmoothlee

Old stories.
By the time the water pump is actually wobbling enough to mill the block, it'll be making noise and probably leaking. Shame on you if you continue to drive on it.

Is it better to have the plastic impeller shred and scatter all over your cooling system? You know, block entire cylinder head cooling ports... you know, stuff like that.

Pick your poison.

OR, a third option. Change your plastic water pump every 15,000 miles.

Don't bet on it. We have had customers come in complaining of overheating issues in heavy traffic. While the metal impeller replacement pumps had some play in them, they were not leaking or making any observable noise at the time we removed them. Along with randomly machined engine cases, the entire cooling system was full of finely disbursed aluminum filings caused by the water pump impeller wear on the cases. After spending a couple hours cleaning the metal out of the entire cooling system and installing a new water pump (composite), the car's still had heat issues, but these were now observed to be caused by the new pump's impeller now having significantly more clearance due to case wear and not being able to move coolant as effectively. Similar instances were recently written up in Excellence Magazine's technical section as well.