Tempting fate

[markwillenbrock]

I knew I should have kept my mouth shut about how well behaved the Ex was...

I now have a really nasty vibration at over 60mph.

It kicks in and out randomly, but is more likely under load or over run.

The noise is road, not engine speed related, and is generally but not always there under load or on over run. It isn't guaranteed - it comes and goes.

It doesn't build or ebb away - it's there, or gone.

My car is right hand drive and my wife says she can feel it beneath her seat - which would be the drivers seat in most Explorers.

It doesn't vary in corners.

If I select 4x4 high manually, the noise disappears.

The vibration is bad enough to make my house keys (kept in the ashtray!) rattle...

I'm guessing a transfer case output bearing, but all suggestions welcome!

I can move the transfer box end of the front driveshaft a little, maybe 1/8 of an inch (I didn't measure it underneath the car in the dark last night!) vertically.

 

[SkanlaxJMO]

might be looking at a new u-joint. My truck did this as well but it got worse when i engaged it in 4x4(auto) at higher speeds. Im not sure why it would go away at high speeds and not get worse. Does it rattle in 4x4 at low speeds? and slowly build into a hum?

 

[markwillenbrock]

Problem identified, if not exactly solved. The front driveshaft joint at the transfer box end has a tiny split in the gaiter and play.

Removing the shaft has cured the vibration, but we'll have to wait for a new joint to be certain that the transfer box doesn't have a problem too.