I used a deflection gauge from gates. Pretty handy tool to get the deflection in the ballpark range. If they squeal now, they will be worse in a couple weeks after the belts stretch.

 

I ordered one of those gauges that slips on your finger so you can press down on the belt and get a reading. It'll be here Wednesday. Thanks for the tip.

 

Gauge came in the other night so I went out and tested everything. The gauge goes from 100-300 lbs of tension, both belts were below 100lbs when I set them. Oops.

Got them both up to the specified range, and yay no squeaky belts.

 

So I've been doing this on my 2006 G35 Sedan, the adjustment bolt on the driver's side is REALLY hard to turn, I'm afraid of breaking the screw. The pulley does not seem to go up and down like I expect, the bolt looks okay I don't see any damage to the threads. I've sprayed it with WD40 just in case since it was a bit dry. Has anyone run into this?

 

that thing gets pretty rusty. Make sure you've loosened the nut on the front of the pulley before trying to turn the adjustment bolt. I ended up just buying whole new pulley assemblies with new bolts.

 

Yes just to reiterate on what Lost is saying. The bolt in the center of the pulley needs to be loosened up FIRST before you can use the tensioner bolt. That center pulley bolt is basically the lock bolt that holds everything from moving.

 

I ended up getting a new adjustment mechanism on ebay. Even after taking the old one out I was not able to adjust the screw at all.

 

Yep, we actually already had the pulley off but that adjustment mechanism would NOT move. Maybe someone tried to adjust it without loosening the nut first at some point because it really makes no sense why it wasn't working. Thanks for the advice.

 

Yep that's almost definitely what happened, someone in the past stripped out the adjuster, fortunately it's a cheap common item.