Quote:
	
	
		| 
					Originally Posted by Gelbster  This subject comes up often but seldom are there detailed explanations of why metal/plastic is the best choice.The threads deteriorate just like the oil chioice threads.Not helpful. I have the curse of an inquiring mind so here are a few details that others may add to/correct.1.The aluminum blades will only score/abrade  the w/p housing if you neglect a worn bearing.
 2.The plastic blades will also mark the housing if a wobbly bearing is neglected. More serious - the plastic blades can disintegrate (but why-age/heat??). You will need to dismantle the entire engine to retrieve all the little pieces .Why? Because they block the coolant passages & then......Just done that job!
 So pick your poison.
 Best suggestion whichever you choose - is watch for coolant leaks from the w/p or noises and replace the pump immediately or 60k miles ?
 | 
	
 
Great info.  And the first post to suggest using the metal impeller pump might not be a horrible idea...  I agree with the overall idea of keeping an eye on it and not letting it get to be an issue either way...