E46Fanatics - View Single Post - idler pulley/hydraulic tension/tensioner pulley..im lost!
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Old 04-12-2012, 07:09 PM   #7
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Join Date: Jul 2011
Location: Southpark
Posts: 53
My Ride: E46 330
Originally Posted by Koffinb View Post
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.
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.

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 07:11 PM.
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