I have a 2007 lt3 suburban with the 5.3 flexfuel. Lately when I start it up it has a loud tapping or ticking noise from the engine area. I read your replies to the gentleman in texas with the 2007 tahoe ltz. The temperature around here lately has been between 10 and 30 degrees. The noise has been going away after the motor warms up. The dealer thinks it might be an exhaust leak. Are we the only ones with this problem and what is your opinion?

 

I've had trouble with the donut gasket on mine. It makes kind of a rapping noise that goes away when the exhaust warms up a seals better.

 

Where is th donut gasket located?

 

Right where the exhaust pipes and exhaust manifolds come together. Unbolt them and there is a big ceramic donut inside.

edit: I forgot to mention with the car running you can feel the exhaust coming out if the seal has any gaps. Be careful not to burn yourself.

 

Thanks I 'll check it out! Also I have been feeling a strange vibration at low speeds through my floorboard and foot peddles at low speeds and when it shifts into second. It seems to happen between 1500 and 2000 rpms. Have you felt this or has anyone else felt this.