I'm having a few issues with my 97 expedition it is a v8 5.4 Triton I have 161,172 miles. About 158000 molts my truck started vibrating at about 50 mph. I went on a vacation, drove long distance. While I was on my trip (Christmas week) my truck had some more issues. All of a sudden when I turned sharp, (parking, making a right hand turn) my back tires felt like they were skipping/jumping across the road. Took it to a machanic he said my gem control is wet and needs to be replaced. It's turning your 4x4 on while your driving and causing these issues. So he disconnected my 4x4 transfer case. Since then I've replaced my windshield replaced the gem controller and still having issues and even started with a new one. About 2 weeks ago my truck started to leak oil bad. It's had a tiny tiny oil leak but it has almost quadrupled what it was. Finally found out where the leaking is coming from. My 4x4 transfer case! The vibration on my truck is getting worse. When I get up to about 30 mph it starts vibrating. You can feel it on the steering wheel and the floor board. The last time I had to take it on the freeway I was going 60 mph and my truck sounded like I was jake braking. When I took my foot off the gas pedal my truck went completely silent. Then when I pressed on my gas the engine engaged and sounded like I was jake braking again. I believe all these issues are coming from the 4x4 xfer case but idk for sure. If it is can I replace it myself? Should I take it to a machanic? On just skeptical now cause of the last machanic ugh.

 

Yes take it to a mechanic....describe your issues you're having, as you have done here. If you do not have confidence in your local mechanic, ask around with co-workers , neighborhood, or other social groups where they take their vehicals to be worked on. BTW...if there was a windsheild leak...then yes, the GEM module can be affected...usually you'll have other odd things happening with dash lights or wipers too.

It seems like a good over all inspection of the suspension, drive line and undercarriage is in order.

Have the mechanic check the U-Joints on both front and rear drive shafts, because this maybe the source of you noise your hearing. Also have the rear end differential fluid/oil changed, the reason for this is that you may have a "limited slip" differential and over time oil breaks down and can give the skipping and jumping feeling, usually, some fresh gear oil with friction modifier remedies that.

Also and mainly, have the oil leak fixed, where ever it is, If it is the Transfer case (aka T-case) fix it....but just refilling the T-case may not silence it. If this has been making noise since Christmas...hmm , hate to be barer of bad news but the oil leak maybe the transmission...here is a better description Ford F150 F250 4WD Makes Noise Why - Ford-Trucks