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Discussion Starter · #1 ·
I have a 2012 Pro-4x with a pretty loud whine under the hood. It kicks in a little over 1500 rpm and definitely gets higher pitched with higher rpms. At idle the whine goes away. I've searched the forums here, but most things seem to point to the secondary timing chain issue on earlier models, and I'm not sure if that is my problem or not. Any ideas?

Thanks!
 

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Does it get louder when you turn on the headlights?

Sometimes, a bad rectifier diode in the alternator will do that. Drawing more current (by turning on the headlights) makes the whine louder.

You might consider picking up a "mechanic's stethoscope", so you can probe around the engine for the source of the noise.
 

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The secondary timing chain issues affected 2005-2010 model years. It's kinda hard to diagnose a noise issue without being able to hear it for oneself.
 

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Discussion Starter · #6 ·
Just a little more info on this. I can start it up and let it idle indefinitely and the whine never starts. I have to rev it to almost 2k before the whine begins. Once it starts, it continues even after letting it drop to idle. If I then turn off the ignition and start it back up, no whine until I rev to around 2k. I tried this same routine with the account on and off, didn't make a difference. Also, these test were done with the transmission in park the whole time. So, what kicks in around 2k and stays engaged until the ignition is turned off?
 

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Obviously a guess, but sounds like it could be the alternater. The reason it doesn't start until 2k and remains at normal idle is you have to get the alt up to a certain rpm to activate or energize it. Once it's activated and "working" it will continue to whine.
Like I said a guess but a definite possibility.
Good luck
 

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Discussion Starter · #8 ·
I just now got up underneath it and it does sound louder underneath and on the passenger side, which would support the alternator theory. The only other thing I can add is that it looks like the seal on the oil filter is blown (or the quick change guy just didn't seat the filter correctly). Could this whine be related to the leak around the oil filter? If not, I'm going to see about swapping out that alternator to see if it helps.
Thanks!
 

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I don't think an oil leak would cause it. Do you have any off road lights or aftermarket amps?
A heavy draw over a shorter period of time could damage the alt.
You could stop by an auto parts store and they can do an in truck check of the charging system including an under load check.
 

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I just now got up underneath it and it does sound louder underneath and on the passenger side, which would support the alternator theory. The only other thing I can add is that it looks like the seal on the oil filter is blown (or the quick change guy just didn't seat the filter correctly). Could this whine be related to the leak around the oil filter? If not, I'm going to see about swapping out that alternator to see if it helps.
Thanks!
Before you buy a new alternator you need to take the belt completely off, rev it up and see if the noise goes away
 

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Discussion Starter · #12 ·
Update

So get this... I took off the belt and tested again - no whine. Picked up a new alternator from Advanced Auto and went to work on removing the old alternator. I got down to the last bolt and that MF'er would not budge. I tried everything, but it just didn't want to move. After spending half a day on it, I finally gave up and put everything back together. I was obviously pretty aggravated, until I started it up. The whine is gone.
 
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