Knock sound
#1
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Knock sound
My car makes a sound that is very similar to rod knock between 900 and ~2500 rpm (after that its gone, or I can't hear it). I did some searching and found that I could isolate the sound (accessory or engine internal) by pulling the serpentine belt and starting the car.
I tried it, and the sound went away completely. I reinstalled the belt, and started the car and the sound is back, so that means one of the pulleys on the serp belt track is doing it. I have no idea how to check them all, and I can't seem to find threads with a related problem. Anyone have an idea of where to start looking? Are any of the accessories run by the serp belt prone to making a knocking sound when they're going bad?
I want to get this fixed before I start modding the car, as I may be able to get it under warranty (dealer already replaced the timing belt thinking that was the cause). Thanks.
I tried it, and the sound went away completely. I reinstalled the belt, and started the car and the sound is back, so that means one of the pulleys on the serp belt track is doing it. I have no idea how to check them all, and I can't seem to find threads with a related problem. Anyone have an idea of where to start looking? Are any of the accessories run by the serp belt prone to making a knocking sound when they're going bad?
I want to get this fixed before I start modding the car, as I may be able to get it under warranty (dealer already replaced the timing belt thinking that was the cause). Thanks.
#3
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I'd start off by taking the belt off again and rotating the idlers and accessories by hand to see if you can feel any roughness. If that doesn't show anything then I would employ an engine stethoscope. A stethoscope, while a big word, is not expensive and it can quickly pinpoint any sounds.
A few words about using a stethoscope around a moving belt: be extremely careful - a belt that catches the probe on the stethoscope will ****** it up so quickly you cannot release your grip in time to avoid running your hand through the belt as well.
A few words about using a stethoscope around a moving belt: be extremely careful - a belt that catches the probe on the stethoscope will ****** it up so quickly you cannot release your grip in time to avoid running your hand through the belt as well.
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