My '98 LT 4x4 (Auto) is making noises that are new. The first is what I'd call a "clatter" that happens when accelerating and arises shortly before the upshift. I get the normal vroom sound at first but the clatter kicks in (pretty loudly) until the shift is completed. The other sound is more of a clicking/ticking sound that seems to be present a lot. It could have been happening for a while but went unnoticed since windows-down driving only started here recently. It not that loud but can easily be heard while stopped at a light, etc. The truck runs well otherwise. Any ideas?

Thanks

 

Possible flex plate is cracked

 

clicking heard with the windows down could be something as simple as a rock stuck in the tire tread. The clatter could be caused by the torque of the motor twisting and causing the exhaust to rattle against something. Its common for the motor mounts to fail on the blazer. With the hood open and brakes applied put it in drive and give it some gas, carefully of course. If the motor seems to rise up quite a bit when the torque is increased the fan could be hitting the shroud or the exhaust rattling. Doing a brake stand while listening in the driveway may help you duplicate the sound and pin point it. Don't run over your helper if you have one looking around while doing this test. LOL. Could also be torque converter chatter which you should probably feel in the floor board or gas pedal.

 

My bad. If clicking can be heard while stopped at a light, it is definitely not a rock in the tire. LOL.