serious metal-on-metal CLUNKING front wheel '98 AWD

Sorry for the long post, but I thought the clues might be in the details.

I purchased a ’98 AWD Explorer with 108,000 miles a few months ago from a dealer who took it as a trade in. It was in good condition and you could tell the previous owner took care of it. It appears to have been a soccer mom’s car due to the rich city where the car was registered (Franklin, TN), and the fact there was little wear to the plastic trim, upholstery and carpet. I do not suspect abuse or serious 4 wheeling as the largest defect to the body is just as few normal road paint chips, no dings or dents.

We drove it for two months with no unusual noises in the engine or drive train. We were driving down the interstate at 70 mph and took a looping off ramp. As we were decelerating I noticed a slight thumping sound starting from the front left tire area. We decided to stop in the first parking lot as the sound started to grow to a moderate thumping sound. I looked at the half shaft and CV boot on both sides and they looked OK. I did not see anything obviously wrong or loose. We decided to slowly drive home 10-15 miles on the back roads since the noise did not sound major. As we pulled onto the road, the sound had disappeared. About a mile down the road it slowly came back to a moderate thump. We pulled over again and no visual problems. I thought I would drive a little slower on the way home and took off again. About 3-4 miles later at 50 mph the noise returned and quickly became a serious clunk by the time I pulled over in 10-15 seconds. I had it towed to my mechanic and told him I thought it was the CV/half shaft. He found a loose steering suspension bolt then drove it a while. I picked it up and immediately took the interstate. The sound disappeared and all was well in OZ….so we thought.

A week later the noise returned when my wife and son were driving it. It was about 5 miles from my mechanic’s shop so I decided to slowly drive it there the next day. I drove about 1 block when the moderate thump became a serious metal-on-metal clunk. I feel like it is still the CV since it appears to be about 3 clunks for each revolution of the tire. I had to drive 1 more block to get into a parking lot. The clunking was so intense I could feel the whole truck shutter on each clunk and my wife could hear it from the car she was driving behind me. I only got up to 10-15 mph when I started and slowed to a crawl when the clunking started. It was again towed to the shop.

The mechanic could hear the clunking as they took it off the roll-back. The next day the mechanic could not duplicate the noise. They drove it up and down the street a while and it would not fail again. He wants to check the front differential and/or the transfer case to look for damage. Since he has to drop the whole front end to get access to the differential, or drop the transmission to check the transfer case, it will cost a lot of shop time to chase an elusive noise/problem.

1) Has any one had a problem like this (constant or intermittent)?
2) Do you think it might be the CV, differential, transfer case or what?
3) Where should we look first?

Any suggestions will be appreciated?


junoflydog@aol.com

I would look at the front driveshaft first. a LOt cheaper than starting the dismantle everything. Is this noticed more with a load? i.e. start up a hill with your foot on the brake and see if you can make it do it. If so, then that's what my transfer case did, but yours sounds much more like when my front driveshaft (between the differential and the transfer case) failed. They could remove the front shaft, and drive it around a bit to see if the noise goes away.

The noise occured with no load, i.e. coasting at 2-3 mph hobbling off of the road.

Sounds more like the driveshaft, except mine was a hard failure (i.e. it didn't go away ever), clunked harder when I turned the wheel. It was the CV joint in the front driveshaft, at the transfer case.

Any other suggestions?:navajo:

Could it possibly be the front sway bar bushing? But then again, if it's making the noise as the wheel is turning.. 3 times or so per revolution... I guess that's out of the question.. I don't know... =\ Sorry.. It was just a thought though..

junoflydog said:

Any other suggestions?:navajo:

Click to expand...

Did you look at the front driveshaft possibility, or did you just not like that idea?

sounds like the front drive shaft or the cv joint, get under the truck and shake them both hard, if either has play replace. also look at the u-joints and check for free play!!!

Also loose brake componets could be doing it, even a badly worn wheel bearing, if you are not mechanicly inclined having it diagnosed will get expensive rather quickly.

Front drive shaft-

I have a friend that went through somewhat the same thing you are. It turned out to be the 4X4 Module causing the Xfer case to try and shift when it couldn't. Search the posts in here. You can disconnect the wiring to the Xfer case and drive like that to see if the noise disappears. That would be a good sign its the Module.

I'd definately check the front d/s first, look around the boot where it mates to the t-case.

rizzjc, I was not trying to discount your suggestion, just trying to get a consensus from a larger group. You were absolutely correct as well as the consensus.


The front drive shaft has a U-joint on one end, and a CV joint on the other. The CV end had no grease and the balls had worn a small groove in the metal. I believe what was happening was the balls would slip out of the grooves when they became non-torqued, then pop back into the grooves when they torqued back on each revolution of the drive shaft. That explains why I got 2-4 consistent major clunks per tire rotation.

I had it replaced early January and no problems since, 9 months later. I appreciate all of the suggestions.