Technical Front End Noise and Reason Why Found - Belt and Pulleys

matreyia

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Apr 19, 2017
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I added the Improved Racing 185 F thermostat to replace the stock N54 thermostat and some oil must have dripped on the belts and pulleys or something. After re-assembly, there was a clicky swoosh swoosh noise in the front end. Visual inspection showed nothing abnormal. But I ordered new idler pulleys and tensioner and belt just in case.

I am glad I did that, because when I removed the belt, I saw a razor thin cut all along the entire belt. See video to hear sound and see damage found.

 
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matreyia

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Apr 19, 2017
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How much time passed between the tstat install and the belt change?

Couple of days. Sound happened only after install...probably oil contamination on metal surfaces causing difference in surface friction on different belt sections.
 

doublespaces

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Oct 18, 2016
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I've heard of belts being ruined by oil but I wasn't aware it could happen so quickly.
 

Rob09msport

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Oct 28, 2017
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Think oil with tight pulley could do it cause pulley slipping on belt cuts it. Dont think the oil hurt it in this case think it just lubes it up enough to slip little
 
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matreyia

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Apr 19, 2017
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Think oil with tight pulley could do it cause pulley slipping on belt cuts it. Dont think the oil hurt it in this case think it just lubes it up enough to slip little
That is what I suspect since I inspected all areas close by and nothing was rubbing at all. And to this day, new belt and pulleys...show zero damage.