I have a 2005 trailblazer with the vortech straight 6. As I am driving I hear a tapping noise as the transmission is switching gears. It also taps lightely in Idle. Inoticed this after I took it to Easy Lube for a synthetic oil change. I then tried to change the oil again and add a oil sedative. Now not as loud but deffinetely still there. One mechanic I took it too said somethings was wrong with the lifters possibly. Chevy told me it was the gears in my fan that needed to be changed. I held my fan while turning on the car and running the motor but stillmakes the t.t.t.t.t.t.t.t..t.t. If I floor it from a dead stop I dont hardly hear it at all. Its just a loud t.t.t.t.t..t.t.t.t.t..t then after 3 rd gear its pretty much gone. I also noticed that it has been burning oil.Has anyone heard of this before ? Any Suggestions? Commets are much appreciated. Thanks Ryan

 

the fuel injectors tick.... but usually you hear that if you open the hood..... not from inside.
also- some of the fan clutches will tick at times. many times when its cold outside. the fan clutchesfail often on the Trailblazers.
try www.trailvoy.com for more info.