I am trying to figure out where to start in search of this strange screech that my 2001 suburban has from the front of the engine. Usually it will start to make the wierd noise (sounds like metal on metal) around 2000 rpms.... It does it while driving and also if I rev it up alittle in park. I know what a water pump usually sounds like and this is a different noise. It also does it with the ac on or off. It has the 5.3 gas engine. Does anybody have any suggestions?

Thanks,

 

Get someone to rev it up and down and place your finger on the back of your alternator. The center is posible. If you can feel the grinding there it is your rear bearing in the alternator going bad. Time for a new alternator.

 

Thanks, I will check the alternator tomorrow when I get home from work.

 

Also check the idler/tensioner for the serpentine belt.

 

I ended up pulling the drivebelt off and running it for a few seconds,,, still have the screech. Figured had to be the ac belt tensioner or ac compressor. Pulled the ac belt off,, no screech. Saw where the ac belt tensioner had one of it's stoppers broken off. The bearing did feel alittle loose also. I believe its going to be the ac belt tensioner. Will head to autozone tomorrow and get one. I will post after its on.

Thanks for help and suggestions

 

Put a new ac belt tensioner on,,, the old one was broken where one of the tabs had been knocked off. Still have the same noise,,,,must be ac compressor. Does anybody have any suggestions on where to get a new compressor kit at a reasonable price? Is remanufactured the way to go? or should I go oem?

 

before replacing take off the belt and spin the a/c pump to see how much it resists

 

I did spin the ac pump yesterday,, it felt normal to me. I have spun other compressors in the past and this one felt like those. If it feels normal is it possible to just put up with the noise at around 2,000 rpm's,,,,, or will it just lock up all of a sudden?

 

I replaced my ac belt tensioner with one from an auto parts store and it still made the sound. I could also move it with my hands so I got a GM one and I could not move it with my hands once installed I was good.

Kevin

 

Probably depends on if it's the compressor that's making the noise. If it is, then it'll probably eventually lockup.