I changed my girlfriends belts about 1 month ago and they are squealing like a *****. I am use to working with a spring loaded idler pulley on other cars when changing the belts, so there is no adjustment necessary like with the Infiniti.

But with her 04 g35x, it is the bolt system to raise and lower the idler pulley.

It seemed easy enough to get to the belts and lower the pulley then put it back up into place nice and snug. It is noted to leave 8-9mm of slack, but to be honest, I don't really know what 8-9 mm is in terms of slack. So I just made it fairly tight and put everything back together.

Now, the problem doesnt happen after every start up, it only happens in the morning or after work when the car hasn't been on for over 8 hours.

On the initial turn on, the car squeals for about 20 seconds then fades away. If I turn the car off and turn it back on, it wont do it again till the car sits again for another 6 hours or more.

So I get underneth and loosen the belts a little, and still the same symptoms. The next day I tighten them good and still the same outcome the next day on start up.

What can the problem be????? Or how do I solve it?

not sure, but i had the same problem after i had them changed. Only squeeked in the morning or after a long day at work, i brought it back and they said they just had to adjust it. May be to tight.

To loose! Try to tighten the adjuster again...

8mm is 1/3 of an inch.

8-9mm with how much force? I feel like the harder I push, the more it flexes...

Its hard to explain the exact amount you need to tighten it. If it is squeeling then you have a problem with it being too loose.

Sounds like you need to tighten it down just a little bit more. The tension that you feel on the belt is best measured by your ability to twist it in your hand. You want to be able to twist it about 120 degrees. I'm not sure if this make as much sense to you as it does to me for how i gauge it.

I have a feeling the same thing will apply. The stronger you are or the harder you try, them more it will twist...

NM, found it in the manual (22 pounds).