It's a bit of a long story. I perused the other posts that had anything to do with overheating or no heat or water pumps. My case seems slightly different. Here's the history:
(1) Summer 2006 -- Installed Steeda Underdrive pulleys. Had to take the de-gas bottle off to do that. Neglected to burp the cooling system.
(2) Weather got cold ... no heat after driving 12-15 minutes. Even after it came on, it would seem very hot but would cut out at idle. I chalked that up to the water pump turning slower because of the U/D pulleys. ALSO, only a few times, the temperature gauge went up about 3/4 of the way to H, which it never had done before. Each time, though, it quickly returned to halfway. I suspected a sticking thermostat.
(3) Logged on to MM.net ... saw that I had to burp the cooling system. Did so. There was a lot of air in there. I thought that had fixed it, but within 3-4 days the symptom (no heat or delayed heat) reappeared.
(4) Took it to the L-M dealer, who said it was not a thermostat, it was the air-temperature control system. This made sense to me, since the hose going into the firewall was very hot, and the one coming out was cold.
(5) Car okay for a while, but then symptom reappeared AGAIN.
(6) Took it back in to L-M dealership. Now they say it is definitely the water pump (covered under Warranty). They say it is making a pretty bad noise.
So, a couple of questions:
(A) Has anyone else had a water pump fail? How about after installing U/D pulleys?
(B) When the water pump fails, does the impeller actually fail to push the water any more? Or is it just loud due to the bearings going bad?
(C) Has anyone who lives in a cold climate installed the U/D pulleys with no degradation in the heater performance?