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Metalic rattling noise when I release the gas pedal

Whenever I am pressing the gas pedal to spead up, then release the gas pedal I get a wierd metalic rattling noise from my engine. It sounds kind of like an old wind up clock being wound up when the spring breaks and releases its energy rapidly by spinning in circles. It does not sound at all like air, it sounds metalic (I think). It only happens when I am releasing the gas pedal after accelerating. The more quickly I release the gas pedal the more dramatic/louder the sound is. It started about a month ago and is now getting louder. Could it be the “high-pitched metalic chatter” of the “heat shield vibration” written about in a Car Talk response by Manolito on 12/02/2008 at 1:54:07am? Any other suggestions on what it could be?

Yes it could be. New to here? why did you forget the details about your car?

Yes, I am BRAND NEW! Just signed up. Thanks for the quick response and orry about the missing info. It is a '99 VW Passat, 4cyl, front wheel drive. It recently had a lot of work done, including a new heat sheild about 5,000 miles ago.

Did any of the work you had done involve rotating parts? Engine mounts,could something be rubbing on a belt or other rotating piece. Can you duplicate without driving. Now that you say you recently have had heat shield work the chance is less,any chance the heat shield work has come apart? Mileage please,any chance your cats. rattling?

I’m not sure what all was done. It was done at the dealer before I bought the car. I just remember one of the things replaced was the heat shield. It is at 85,000 miles right now (79,000 when taken off the lot). How would I know if the heat shield work has come apart, and what is the “cats. rattling”?

Catalytic converter=cats. rattling. You would need to inspect the heat shield (visualy,get car on a lift). Search your owners manual and see if you have a timing belt interval replacement or a invoice that it has been done. Can you make the noise while the car is not moving? If your car does have a timing belt replacement interval you must find out where you are in regards to replacing it.

I can only get the noise to happen while driving, after accelerating. I do not have information ont he timing belt interval replacement.

That sounds like a bad rod bearing.

I know we are all trying to help but I discount the rod bearing idea because the noise cannot be duplicated while the car is stationary. With such low miles rod bearing is not on my list. I would like to know if the timing belt was replaced and possibly some thing has gone wrong with that repair.

I would be helpful if the OP could do some inspection and eliminate some things.

Does anyone know what the replacement interval is on the belt? This is a secondary issue but the OP must get on schedule.

Thank you so much for the helpful information! I will contact the VW dealership where I purchased the car to see about the timing belt. And I need to ask, what does OP mean, and how much would you expect to be a reasonable charge for this inspection (living in Chicago)?

OP= original poster…the person who started the thread.