2007 RAV4 V6 with 138,000 kms. Have this rattle on cold startup. Lasts only for a few seconds and sounds like it is coming from under the vehicle. Sounds very tinny, so crawled under the vehicle to check heat shields. They were in place, and not touching any of the exhaust or loose. Further inspection of other things that may be loose turned up nothing. This does not happen every time on cold startup, so not sure if it is serious. Was wondering if anyone has experienced similar and hopefully not an internal engine issue.