Our excursion usually sits unless we are towing or need to haul a group of people. The past three days my wife has been using it as a commuter. Yesterday she told me that two times at start-up she has heard a loud clunk/thump sound coming from the rear of the vehicle. At first she thought it was happening when she engaged the brake to put it in drive. Today she called me and told me the sound came just after start-up while the vehicle was warming up before the brake was applied.

Any ideas on what this could be? I wish I would have observed it so I could give more details.

 

Ever resolve? Having same issue, V10 2004.

 

It may be as siimple as your exhaust clunking on something underneath under the intial torque of a start up. Maybe you lost an exhaust hanger (rubber isolator that hangs the exhasut to the body) and the exhaust has too much free movement. Things tend to move and rattle more on start ups than just torque from accelleration.

This may be a long shot but the driveline may still be engaging a little while in park. If so, your rear driveshaft may need to be greased at the slip yoke. I had this happen on our old '97 4Runner but it happened after it was started and put into drive. There was enough slop, due to the splines being bone dry, for it to clunk. I have not verified this to be the same on the Fords, just throwing out another possibility.