I have a 2005 F-150 XLT with 54,000 km on it that's been having problems lately. Basically I'll be driving along, regardless of what speed I'm at (as long as it's over 20-30 km/h) and suddenly a loud grinding/buzzing noise will start from underneath the truck.

I do not lose power or stability or revs in the engine, nothing at all. Just this noise starts going, and it really sounds like the truck is in pain. The sound does not go away until I slow down to around 20 km/h or so, at which point the buzzing gets louder, followed by a clunk noise in the front and a very very slight lurch (like something clicking back into place for example) follwed by the back ends buzzing noise getting louder, then making the clunk noise as well. After each clunk, the noise in that area is gone, and there are only two areas where it does it, at the front and back.

I've tested out what happens when in 4x4 and it has not yet made the noise while in 4x4. If overdrive is on or off it does not matter as it will make it with it either on or off regardless.

It's already been in and the tranny overhauled once, however that obviously did not solve the problem even after they put some new parts into it.

The warranty is for 60,000 km and it's a lease that I think the dealership will keep doing patch jobs on until the truck blows over 60k and they can ream my *** for a new tranny/diffs, or something along those lines.

Can anyone help out?

 

Did they replace the rubber mounts when tranny was re-installed? Or maybe mounts are loose....?

 

I'm not sure what they did. I don't know much about cars and they were pretty sketchy on the details of what they did. While I don't know a lot about cars, I knew that they probably didn't fix the problem and were just replacing small parts and hoping I don't come back until I blow over 60,000 km.

I've tried putting it in 4x4 while driving while it was making the noise, and the noise stops once I do it. So it leads me to believe it's something with the diffs perhaps?

 

I know what it is....I had the same thing, more or less. The truck is partially engaging the 4x4 while going down the road on it's own. It makes a terrible noise - like syncro gears trying to mesh, but goes away as soon as you push the 4x4 button. The dealer replaced the module controlling this and the problem was fixed. Get to the dealer quick. This cannot be good for any parts involved and will probably thrash the entire transfer case if not fixed.

 

Thank you! It's not being driven again until it goes in, and it's going in on Monday. I'll tell them this is what needs to be done. Hopefully the dumbasses get it this time. Thank you TJI!