Pulleys can develop play and yet work without causing any noise. Most of the time - when you have a high pitched noise at idle - its the mechanical tensioner (what I guess you have). Its the noise problem why I have gone from mechanical to hydraulic tensioner on my E39 and E46. The hydraulic tensioners work just fine. If youre not sure if its the tensioner - pour some water over a pulley while engine is running. If noise is still there - go for next pulley/tensioner.
Originally Posted by Koffinb
Need to replace my idler pulley and tensioner pulley due to an annoying high pitched sound I get at idle.
Does the hydraulic tensioner cause a noise too? All belts are in great condition so i'm good there.
What you should do is remove the fan, remove the belts (water pump belt and AC belt) and check ALL pulleys. Spin them and see if they spin for a long time or stop quickly. If they stop quickly the bearing is bad. Also pull/push the pulleys along the axis - if theres any play - bearing is bad.
Check the belt on the inside where the ribs are. See if there are any cracks.
I change the water pumps on all my cars every 100.000km. When I do I usually change all my pulleys and the belts as well. This way - you have another 100.000 carefree kilometers.
If you only change one pulley - how do you know when the next one is due?
Last edited by silyb0y; 04-12-2012 at 08:11 PM.