Hello, I have an 08 Avalanche that has a replacement motor (2 years ago) with 115k miles on it. Great Oil Pressure, No missing, No oil burn, but the last few months the AFM when active had gotten so loud that it sounded like a Jake Brake on a big rig when i let off the gas. So after talking with a friend he said have it turned off. I paid a guy $200 to disable it in the computer. He said motor looked good and strong on the computer. Not missing at all.

Well the Jake brake went away but there is still a sound that is getting worse that is different. This one is a rattle sound coming from back on the Passanger side or maybe on top. What would cause this sound at idle and when you let off the gas, BUT as soon as there is any power to the motor or load the sound is gone and it sounds like a perfect running engine? It's a rattle sound that is getting louder. What could make this noise? Is it going to make somethings worse?

Thanks for the help

https://drive.google.com/file/d/12lv...ew?usp=sharing

 

That noise sounds awful. Definitely not like a Jake Brake (I should know, as I am a commercial driver). I have never liked the AFM motors for reason like this.

Are you showing any OBD II codes on a scan-tool?

What is the displacement of your motor? 5.3 liter?