I have a 2006 Tahoe that just started making a rattling noise that seems to be coming from the trans. It happens at part throttle just before the 2-3 shift. It sounds like a heat sheild rattling under water. If you go easy on the throtlle it does not do it. WOT it does not do it either. Just at part throttle. The trans seems to be working fine. It is not slipping or doing anything odd just a noise. 1-2 & 3-4 shifts are quite no noise. 3-2 down shift is quite also. I held it in 2nd and ran through the rpm range and no sound. It only does it right before the 2-3. Any ideas?

 

Well this issue continues I have done everything other than putting a new trans in. It now has the rattling noise just before the 1-2 shift also. The only thing that has changed is that it only does it when it is cold first thing in the morning. I have let sit idling till up to temp and no difference. Once it shifts a few times the noise goes away. The trans feels fine seems to shift good no performance issues. Any ideas?

 

Did u check for loose tq converter bolts?

 

Cats coming apart & rattling?

 

I am going to check those tonight. Fingers crossed.

 

Possible. I have heard some cats comming apart in my friends NHRA TransAM that sounded like major rod knock. He changed them out and its silent now.

 

Cracked or loose flexplate? What do you have for servo's?

 

Survey says????????

 

This would be my first guess...try whacking your cats with a rubber mallet and see what you hear...

 

Thanks for the input but the search for the noise continues. Checked the converter bolts and they are all tight did not see any signs of the flex plate cracking. Tapped the cats and they sound solid no rattling. This is driving me crazy!