4.6 V8 Rattle in gear, Loose Marble Noise, Tin Can...

[CommandPresence]

So initial thought is the torque converter rattle. I'll break it down for you. Noise is NOT there while moving, or in neutral. Sitting idling in drive, sometimes park, reverse, 3 2 1, rattlerattlerattle loose marble from starter area underneath the car. RPM range for the noise is from 7-900, then disappears completely. Let off, let it come back down, lightly hit throttle, it re appears. No performance issues or shifting issues at all. Would this still be a torque converter issue with problem described, as no issues while moving or in such a small rpm range? Seems when the drivetrain shifts when put into gear it's more prominent. Heat shields 'seem' to be all intact as i inspected all with flathead. Any thoughts? My understanding with torque converter is it would be in a broader range of rpms and also heard while driving until it locks. Possible starter need shimming? shimmed improperly?

 

[CommandPresence]

Uploaded a sound file of it that I recorded with my phone. taken from drivers side wheelwell area.

http://www.filefactory.com/file/c2c9b20/n/20120123_170048.wav

 

[94Eddie]

One of the sure ways to determine if it is the torque convertor is if the noise goes away when overdrive is engaged. I have the torque convertor noise and it rattles like a can with a dozen pennies in it except when the tranny locks up in overdrive.

 

[CommandPresence]

That won't help me. I can't hear the noise when moving at all. It goes away. Only time it can be heard is at a drive thru, or sitting at a stoplight. No noise after 900 rpms. OD on and off button doesn't change noise either.

 

[94Eddie]

You have to get above 40-45 mph before OD will engage. Sometimes driving next to a guardrail with the facing window down can help to enhance hearing the noise. In my case, it is obvious the noise stops the moment the transmission shifts to overdrive. My noise will also go away with hard acceleration. Maybe yours isn't as pronounced and it stops, or becomes less noticeable, under a more moderate load.

 

[CommandPresence]

Mine is only evident between 6-900 rpms though, even in park, neutral.

 

[94Eddie]

That sounds like the noise might be a frequency dependent vibration. Maybe it is a loose heat shield or something similar.

 

[CommandPresence]

Gotta get under it this weekend. Driving me nuts!