What a PITA. Car: My mothers 1996 I30, 85k miles, VQ30DE of course.

Bought a new idler pulley and Nissan genuine belts (inner and outer) from the dealer and installed them today. When the car heats up, it starts to whistle on idle. When the thottle is open at all, the idle stops.

Autozone said the alternator is fine. The thermostat is also new, but I'm not sure if it's working. When the car is warmed up, the lower radiator hose gets warm/hot, but the upper hose stays cool.

1. Could the new t-stat be causing the whistle?

2. Should the upper radiator hose be getting hot?

Another thing that I must mention is that I bought the T-stat from Pep Boys, and it looked a little different than the T-stat that came off the car... it still bolted in exactly the same, but the t-stat itsef, the parts on the inside, were different. Not sure if that has anything to do with it.

Your thoughts?

 

The definitave fix for this problem is believe it or not is the water pump...
I had the same annoying problem as you and changed the same stuff as you. After changing the tensioner & belts didnt work I traced it to the pump.

I dreaded changing it and put it off for as long as I could stand it.

It wasnt too bad of a job...2 1/2 hours with new hoses & t-stat and no more noise