2004 Sport Trac, Clunking noise in front end when in 4wd

[04st]

There is a loud clunking noise coming from the front end when in 4WD in my 04 Sport Trac XLS. The clunking noise happens when the truck is in slippery mud / snow / off road conditions. The clunking continues if I try to accelerate. Clunk - Clunk - Clunk. It almost sounds as if the front is "slipping"??? Please help! Thanks!

 

[ncranchero]

Sounds like a bad CV joint on the axle half-shaft.

 

[TonkaRanger3.0]

definitely sounds like a bad cv-shaft

 

[04st]

Thanks for the reply guys. The cv joints / boots look good. The clunking noise only happens under medium to heavy load (for example, driving offroad on a muddy or snowy hill) in 4wd. When I am on pavement, I can accelerate and the clunking noise is not there, please advise.

 

[MidnightRebel07]

04ST, You said,

When I am on pavement, I can accelerate and the clunking noise is not there, please advise

Is this in 4wd or 2wd? If 2wd then it won't make any noise because there's no load put on the axle shafts.

I would agree that it is the CV Axle or Axles, have both checked out because you don't want them to break apart on you out on the trail.

 

[04st]

The popping noise happens under medium to heavy load. It only happens in
4wd. Does the ST have automatic hubs? If so, how do I test them? The noise almost sounds like a banging / popping sound on the front drivers side. It seems as if the 4wd is disengaging causing the popping. Thanks.

 

[04st]

UPDATE: I noticed a broken / cracked bushing on the long bracket that goes from the front differential and mounts to the frame towards the rear. Could a bad bushings cause the clunking / binding sound? It only happens in 4wd, so I am not sure? I also re-created the noise by turning slightly on pavement at low speed in 4wd. The front wheels seem to still turn and the cv / u joints and axles / driveshaft (drivetrain) all look good. The bracket looks difficult to remove. Can I just replace the bushing while the mount is still attached to the truck. Do you guys have a part number or a link to the bushing? Any other busings / mounts I should look out for? Thanks!


Here is a pic I found on the internet of the bushing in question:

http://i73.photobucket.com/albums/i232/WingmanSVT/IMG_2627.jpg

 

[ncranchero]

That bushing is one of the three front axle mounting bushings. That in fact could cause the problems you mention. This should help with the location of a replacement. In this application I looked up for the 2004 it appears the bushing and bracket are one. In my 2002 Parts Manual the bushing is shown as a F67Z-3A443-AA and separate from the bracket.

http://www.fordparts.com/

 

[04st]

Upon further examination, the buhing was ok, the part is molded with "ears" on it, giving the false impression the bushing was torn / broken. Thanks!

 

[04st]

UPDATE: My mechanic was able to find a replacement Transfer case for $250 at the local salvage yard. The new transfer case fixed the problem. The binding / clunking noise in the front end while in 4wd was caused by a slipping chain in the transfer case. Thanks everyone!

 

[ncranchero]

Reasonable enough!