Chugging noise diagnosis / Crankshaft pulley replacement

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Chugging noise diagnosis / Crankshaft pulley replacement

Post by rvinegar » Thu Jun 28, 2018 6:14 pm


First post here, been lurking the last few years since I got my 2005 Vibe AWD 1.8L.

The last couple months I've had an engine chugging noise which has progressively worsened. I don't drive much so have been slow to handle it. The noise is present when idling but increases in pitch when the engine is revving. Haven't really examined how AC affects it, but I did get in there with a metal broom handle to see where the vibration is:

My sense from this test is it is the crankshaft pulley. Would you agree? (also crankshaft pulley = harmonic balancer?)
The water pump pulley made a little bit of noise but wasn't too loud, relatively. The AC pulley I couldn't actually touch with the pole since it has a plate covering it.

Any opinions on replacing this part at home? Angles look tricky and I hear it can be hard to get adequate torque. I don't have a torque gun (does Parts Source loan those?)
Also, is it worth looking at used parts from a junker?

Similar process on the Vibe?


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Re: Chugging noise diagnosis / Crankshaft pulley replacement

Post by vibrologist » Fri Jun 29, 2018 7:32 am

Wow, that sounds horrible!

A video makes it hard to tell where that sound comes from. I fact my immediate thought was that the engine is running on 3 cylinders. You may want to disconnect the coils one at a time. The one where the removal of the coil does make no difference is the bad cylinder. Just do it to prove me wrong.

This could also be a rod knock. And yes you are likely to feel that at the pulley. A compression test will tell which rod knocks.

Another way to isolate the source of a noise is to remove the drive belt and run the engine for no more than one minute. If the noise goes away it is something that's driven by the belt. If the noise does not change it is the engine or directly driven by the engine. If it is the pulley you should be able to see some damage or feel it being loose on the crankshaft.
'05 Vibe

"It is important to know the difference between 'accurate' and 'precise' even if you are neither!"


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Re: Chugging noise diagnosis / Crankshaft pulley replacement

Post by joatmon » Fri Jun 29, 2018 7:45 am

I'm not sure what you're doing with the metal broom handle in the video.

Since the crankshaft pulley is tied to the crankshaft, and is what drives everything else on the serpentine belt, I'm not sure what replacing the pulley would accomplish. If it were coming from the crank pulley, then I'd think it more the main crank bearing instead of the pulley, but lets hope thats not what it is. But that's just a guess

I agree with vibroligist, take the serpentine belt off and see if the noise goes away, but and don't run it for long, and perhaps with the engine cold since the belt drives the water pump.

Statistically speaking, the belt tensioner is a much higher probability failure item, there have been more than a few of them reported here over the last 16 years of Vibiing, where I'm pretty sure you'd be the first here to have a crank pulley fail.

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