My daughter's 2003 Trail Blazer has had a kind of clicking/grinding noise at the rear end for two seasons now and I have been unable to determine what it is.

This season it has become very loud. It starts almost immediately after she begins to accelerate and is constant after. It is hard to describe in words, of course, but she says it's like a roller coaster. I disagree. First, it is not that consistent.

Sounds more like a grinding noise to me. We just started into this. We removed the rear sprocket and chain and loosened the rear axle. The rear bearings appear to be in good shape (from what can be seen from the outside, anyway) but they don't have any play so I am eliminating blown bearings.

The chain and rear sprocket appear to be in decent shape. They show wear, of course, but nothing outrageous.

I will get to the front sprocket tonight and see how that looks. However, if that is in good shape, I am leaning toward the silent chain. Does that chain make grinding noises before failure? What are the symptoms of impending failure of the silent chain?

We also removed the rear clutch (so I can replace the buttons - but I need to replace my c-clip pliers) and the belt was in good shape but I have a new one to put in there anyway...

 

Silent chains can start making a grinding noise upon take off or under a load. They can start off with noise occasionally,then as they wear the noise becomes louder and the machine will slip and jump. Then when totally worn out, all the machine does in gear is just grind and doesn't move. I've had em brought in all the above conditions. Usually the last stage is when customers just rode em to death and brought em to me..
But a grinding/clicking noise could just be a bad ball or two in the rear axle bearings even though you don't feel any play.Had that happen a lot. OPT

 

OPT, thanks!

I took the front sprocket off. The entire inside is worn down. I mean the side face! It's all nice 'n shiny!! There is a step and it's obvious the chain has been rubbing against that face and has worn down a "step" that is probably .010"!!

When I get to my other computer I'll upload a pic for you to see. I believe this to be the source of the noise. however, I have rear bearings so I'm going to install them while I'm at this point.

The bigger issue is how I keep the sprocket from wearing down like that again. There was a CRAP TON of mud caked around tranny casing right behind the sprocket! The flange was facing toward the engine... If it were backward, it would be a worse condition.