hello Monte Carlo fans,
I am new to this site. this is 1st time I have posted anything about my Monte Carlo. I have a 2000 Monte Carlo ss pace car replica that just hit 148,000 miles. only thing I have done is tranny rebuild at 85K and water pump at 110K. it is starting to show i's age a little bit, but still moves quickly. anyways, within the last couple of days I have been getting a rattling noise from my transmission. it shifts smooth, and in gear, and does what it is supposed to do, but it makes a rattling sound when in park. as soon as you shift into reverse or drive, it goes away. also the sound is noticeable when warmed up, not so noticeable when car is cold. any suggestions?

 

I do not know the answer to your question but welcome to the forum!!

 

Welcome to the forum.

Are you certain the noise is coming from the transmission? It sounds to me more like something is loose in and around that area and when you put the load on the tranny it shifts causing the noise to decrease. If you have access to a hoist or feel like laying on the ground I would give the exhaust a once over as it could be a hanger rattling, just a guess but that's where I would start

 

There is the potential to be a cracked flexplate (where the tranny meets the engine)