Engine Grind Hitting Passing Gear

[swep1]

My '96 Eddie Bauer Explorer recently hit 97,000 miles and I have noticed especially while quickly accelerating while driving uphill a clunking noise or hiccup as the transmission changes into what my mechanic calls the "passing gear." I changed the fuel filter, air filter, added new plugs and plug wires and although not nearly as bad, it still makes this noise. Took the truck in and had the transmission checked and a full diagnostic run and my mechanic's conclusion was that without costly exploratory repairs that he had no definite explanation for why this happens but as long as the truck was running well otherwise that he wouldn't bother trying to track it down. Anyone else experienced something like this?

 

[swep1]

In the last few minutes since posting this thread I've noticed several discussions about this potentially being a transfer case problem and leading to bigger problems down the road. I should add that I have owned this vehicle for 3 years now (bought it used with 37,000 miles) and it has made this same noise since I purchased it and it has concerned me for 3 years. It doesn't happen frequently, never on level ground and only if I really step on the accelerator, not a problem if I smoothly and slowly accelerate even up an incline and will happen as well if the cruise control is engaged. I just recently found this message board and your help has been exceptional on a couple other minor issues, so I was hoping that you all may have an explanation for this as well...

 

[Jason_25]

Any chance you have a 5.0L V8? The automatic transmission that is paired with it can make a grinding/shuddering noise on the shift from 3-4 and 4-3. The problem is due to loose valve body bolts. If you have the 4.0, then the only thing I can think of is that maybe the tranny is slipping.

 

[jimbo74]

Welcome to the site... maybe its a u joint? sudden hard acceleration could make the driveshaft snap whereas at slow speeds the slop is spread out to an unfeelable level?

 

[swep1]

It is a 4.0...

I figured it might be the tranny slipping but the mechanic says that if it's been doing this for 3 years that it probably would be getting worse if it was the transmission slipping...and it doesn''t really seem to be...