Noise in 4WD

[Mrojec]

I have a '93 XLT with 182k that's been making a low rumbling noise in 4wd for the last 2 or 3 winters. It seems to drive fine but it rumbles for 20-30 seconds at a time, then there's a low clunk, and it's quiet for a few seconds, then it starts the rumbling/clunk/quiet cycle all over again. It's most noticeable when accelerating and when coasting in gear. Does anyone have any ideas what could be causing this? My fear is, of course, that it'll suddenly seize up or quit when I need it most. I have Warn manual hubs but the noise was occurring before I installed these and didn't change after the installation.

 

[ExplorerSportNu]

Welcome to the site, not sure on your tranny question but I'm sure someone will chime in for ya

 

[DeRocha]

Can you tell where the noise is coming from (wheels, drive shaft, transmission)? When were the Ujoints last changed? As they get old the lube leaks out and moiture gets in rusting the needle bearings. When did last change or check the T-case fluid?

 

[Mrojec]

The u joints have never been replaced, and I changed the oil in the front differential earlier this year. I don't think the transfer case fluid has ever been changed. I did Singleton's fix for the transfer case not shifting a few years ago. I'm embarrassed to say it, but I am the original owner of the car. I do change the oil every 3000 miles, though! Thanks--Mark

 

[DeRocha]

I would change the T-Case fluid asap. It is a piece of cake to do. You only need to remove the balancer, remove the lower drain plug & uppper fill plug (with a 3/8" socket extension). You then put the drain plug back and add fluid until it reaches the fill plug. Put everything back and you're good to go.

The U-joints @ the wheels on my '93 were VERY rusted when I changed them a year ago (first time). They U-joints should move freely, but I could barely articulate the axle shaft using a pry bar - Not good. The rest of the U-joints were not rusted, but they needed to be changed all the same.

Where does the sound appear to come from? If you lock the HUBs without engaging 4x4 what happens in regard to the noise and drivetrain feel?

 

[Mrojec]

I was wrong on the u-joints. They were changed 50,000 mi ago when I had the front end serviced. The noise seems to be coming from the left front, and it doesn't happen when driving in 2wd with the hubs locked. I'll change the txfer case fluid today and see what happens. Thanks--Mark

 

[Mrojec]

Changing the transfer case fluid made no difference, but I feel better having done it. There is a similar rumble with the 4wd on but with the hubs disengaged, so I'm thinking it's the front shaft u-joints, which have never been replaced. I bought new ones at Checker yesterday for $10 apiece and will put them in this weekend. Stand by for a follow-up post.
Mark

 

[DeRocha]

How are your wheel & spindle bearings? Their normal lifespan is rated at 100K, but obvsioulsy they can easily last longer depending on maintenance factors. When pulling the rotors to replace the U-joints you should check the bearings for any signs of wear or high temp bluing. The spindle bearing as the name implies is pressed into the backside of the spindle and is used to center the axle shaft in the spindle. If you haven't already the links in my sig line show how the "C" clamp tool is used to replace U-joints.