Another Pulley Noise/Problem...

[Soichiro Jr.]

Hello Everyone-

I have a 2007 Si coupe with 33,XXXmi. I have searched this site over and over to look for a possible solution to this problem. I've found similar problems posted, but no exact matches. I recently installed a set of NST pulleys. The install went ok, and the car ran perfect for about 3 weeks. Then it started making a noise coming from the pulley area. The noise started out as a clicking noise that would fluctuate with engine rpms. Then after a couple of days, it turned into a louder, constant "whurring"-type sound. Now, it's very loud and sounds just like a raspy thrashing going on under the hood. Sounds kinda like when my uncle got his catalytic converter "fixed" in TJ. The noise starts as soon as the car does(doesn't matter if the car is warm or cold).

I've been suspecting that it was the bearings in the NST idler pulley, so today I removed the belt completely and started the car. The car sounded perfect no more noise! Now, I knew for sure that the belt and pulleys were involved. I assumed that it was indeed the NST idler pulley, so I took it off(leaving the other 2 NST pulleys on) and replaced it with the stock OEM idler pulley. I knew that, if I was to run the car like this, I'd need a belt about 1" to 1 1/2" shorter than the stock belt(I called NST and asked)... But just to test it, I replaced the stock belt(over the NST crank, NST alternator and OEM idler pulleys), and it was loose. I started the car, and it sounded perfect. I got out to take a peek under the hood. The pulleys appeared(didn't notice the alt. pulley) to be spinning as was the belt, but it was very loose. I now concluded that the NST idler pulley was to blame.

Now, I began my search for a smaller belt. The closest belt I could find was at Napa, and it was 64 5/8" long compared to the stock 66 1/2" belt. I installed the new Napa belt, and it fit nicely(if a little tight). I started the car, and it was still making the noise! I can now rule out the NST idler pulley, as the noise is still present with the OEM idler pulley in place. I repeat, IT'S NOT THE NST IDLER PULLEY. I now think it's either the tension pulley or the alternator pulley. When the belt was completely off, I spun the various pulleys with my hand to see, if any of them made noise. I noticed that there was a very little bit of play in the tension pulley. I also noticed that the alternator pulley didn't spin freely. I could turn it by hand, but it required a little bit of effort and there was one spot in it's revolution that was rough and took more effort to spin past. I wonder if I tightened the alternator pulley too tight? If anyone can help me out with some suggestions, I'd really appreciate it. I'm very frustrated at this point. Thanks for any input/suggestions anyone may have.

[Soichiro Jr.]

Well, I believe the problem is solved(know for sure tomorrow). It appears, I over tightened the alternator pulley. It was rubbing against the alt bearing. The bearing eventually failed(@pprox 3.5 weeks), which allowed the alternator shaft to weeble-wobble increasingly so at an alarming rate with every revolution of this overworked 2 liter overachiever, thereby forcing the once overtightened pulley nut to actually begin to back itself off it's rightful perch upon the alternator's threaded shaft, until, alas, the nut's cruel fate, became a reality for you and me, effectively fusing the lightweight pulley to the out of control alternator's almost molten, metal, machined man meat in the process; or what have you.

By the way, if any of you are seeking torque specs for the full 3-piece NST K20 Pulley Kit, I believe it goes like this-> Idler Pulley= 28ft./lbs, Alt. Pulley= 30ft/lbs and Crank Pulley= up to 120ft./lbs. I received the first 2 specs from NST over the phone, and I stumbled upon the crank pulley specs in one of the multiple NST threads I've read/searched. If these are wrong, someone please feel free to set the record straight; if you may wish, I .....

[Kylie_FD3S]

My bf has NST pulleys and he and my brother were the ones who installed it like a year or so ago and his car runs perfectly fine. He's never had any problem with it since the installation. I'm sorry it turned out this way for u. Glad the problem is fixed now. Good luck with everything!