I have a 99 blazer 4x4 and there is a very weird noise coming from the engine ompartment. Its a scraping grinding gergliing noise. It starts when the engine is idling, the more rpms the more steady it gets. It sounds like its oming from the alternator region. Everything seems to be working fine, great starting, battery is being charged theres just a bad noise and dont want to get stranded.

 

The alternator could have a bad bearing or either of the two pulleys(idler or tensioner) could also have a bad bearing. Two quick checks are to either disengage the belt from the tensioner and spin all three by hand and listen for noise and feel for binding/roughness. You can also take a long socket extension and use it as a stethescope while running to probe around the area to try to find the noise.

 

ill check that tomorrow and let yas know. When doing the tesioner back up how do you know when its tight enough and whens its too tight?

 

you don't adjust the tensioner, it's self adjusting.

have you never replaced the belt before?