'97 XLT 4wd 200k+ miles, metal on metal scraping noise

[CHilton68]

Hey y'all. Let me start by thanking you in advance for reading this post and putting in your time and effort. So I was in need of a vehicle and could only afford a "beater with a heater". So that is exactly what I got. The heater works great, just can't adjust the temperature, but that's for another post(s) along with the other issues it has lol.

I'm most concerned with this noise I hear coming from the underside of the truck. It's only upon acceleration (at least I'm 90% sure it's only on acceration). It's not loud but it's definitely a sign something is wrong.

Question, does the drive shaft still spin when you're not accelerating? If it does spin while not accelerating then that leads me to believe it's NOT a heat shield or similar issue scraping against the drive shaft. That fix would be too easy LOL.

The sound isn't completely consistent meaning it's not evenly timed but it is the same sound each time...if that makes any sense. I'm going to try and get a recording of the sound and post a link if that would help.

PS could it have anything to do with the fact that when I turn hard left or hard right and move forward that the wheels hop?

 

[roscoe 0202]

get under the car with transmission in neutral wheels chocked and see if the u-joints are lose
roscoe

 

[Mbrooks420]

The driveshaft spins any time the wheels do.

 

[roscoe 0202]

don't spin it shake it side to side to check for bad u-joints
roscoe

 

[Mbrooks420]

If the wheels are hopping it’s trying to drive in 4wd most likely, and you are getting driveline wind up.

Do you have 4 tires of the exact same brand, model, size, and worn similar?

 

[CHilton68]

Thx for the tips... I'll let you know what I find as soon as I can find a place to work on her.

 

[CHilton68]

If the wheels are hopping it’s trying to drive in 4wd most likely, and you are getting driveline wind up.

Do you have 4 tires of the exact same brand, model, size, and worn similar?

I'll have to check the tire sizes but as far as I could tell from the manual it's always in 4wd "Auto" but it can be switched to 4wd "high" and or "low". Meaning the switch has three positions: 1. Auto, 2. High, & 3. Low

I thought it was like most four-wheel drive vehicles I'm accustomed to, being able to switch from 2wd to 4wd, until I read the owner's manual (if I understand it correctly). But that doesn't seem to be the case with this truck.

 

[Mbrooks420]

It powers the front when the rears slip in auto. Search “brown wire mod” for an easy way to get true 2wd.

 

[CHilton68]

It powers the front when the rears slip in auto. Search “brown wire mod” for an easy way to get true 2wd.

Ahhh that makes sense now. So it shouldn't always normally be in 4wd, thus either something is wrong and it's stuck in 4wd or it's another issue like the tires not matching. Excellent info. Thx

 

[XLTrunner]

Just to clarify what Mbrooks was saying about the brown wire mod...your truck is NEVER in true 2WD. There is always a small percentage of power being directed to the front driveline in Auto mode. Thus, something like mismatched tires can cause it to direct a larger percentage of power to the front and cause driveline binding on dry roads.