Clunking while in 4wd going up hills

[osujason]

experiment time.

put it in 4wd, drive slow with a heavy foot on the brakes to simulate load.

what happens?


if results are inconclusive try a "crude" experiment: park on dirt and chain it to a tree, 4wd lo and see what happens.

since we are like totally environmentally responsible guys, be sure to use a strap around the tree


(and stop the experiment if the tree starts to fall)

So I put it in 4wd while hitting the brakes and gas pedal at the same time to simulate a load, I was able to pull forward slowly, but there was no clunking to my surprise. I was not yet able to perform the "crude" tow strap experiment yet.

 

[osujason]

Well, per @Grumpaw, I'm going to be the wingnut/misfit, and suggest a major conversion to The Dreaded Pulse Vacuum Hub (PVH) system... not only will you get better MPGs when NOT in 4WD, but I once pulled out a tree stump with my PVH system--4LO, in Reverse, using those beefy TOW HOOKS up front--and NO UPHILL CLUNKING afterwards, lol...

Seriously though, how many clunks per wheel rotation would you say you're hearing/feeling? That would be a clue as to which link in the chain is breaking down.

So after looking at it this weekend some, I can definitely say there is no consistent 4wd clunk per wheel rotation while under load. It might range from 5 rotations to 30 rotations. The other thing I noticed a few time was that it even clunked in 4wd a few time while hitting the brakes to stop, although that was definitely more infrequent when compared to clunks occurring in 4wd going uphill. So there are no clunks in 4wd while coasting or lightly accelerating, but we do get clunks in 4wd going uphill, moderate to heavy acceleration and occasionally while braking.

 

[pjtoledo]

once upon a time there were issues with the rear driveshaft not sliding on the splines smoothly. that was more of a clunk than slipping. anyway it's an inexpensive fix, just grease the splines
with the proper lube.
may or may not fix it, but won't hurt to do it.

 

[fixizin]

And thee most proper lube for CLUNKY Ford Ranger driveshafts is... Motorcraft XG-8! It's "baby blue" in color, but... no one will question your man-cred cuz it's out of sight, down under, so to speak... a 3 oz. tube (enough to do the slippy-clunky driveshaft at least 2, and some say 3 times) costs $28.xx+ at Ford Parts Counter... or $6.29 at O'Reilly... I sheet ye not. I'm about to use a modest quantity on my PVH hubs... expecting great things, lol...

Being fully synthetic, XG-8 is also safe for (most) plastics... soze Ima use some on my eh-spensive Herman Miller office chair... soon az ah ken figure out exactly where da squeak be comin' from...

 

[osujason]

once upon a time there were issues with the rear driveshaft not sliding on the splines smoothly. that was more of a clunk than slipping. anyway it's an inexpensive fix, just grease the splines
with the proper lube.
may or may not fix it, but won't hurt to do it.

I know what you are referring to but this only occurs while in 4wd and under load.

 

[osujason]

And thee most proper lube for CLUNKY Ford Ranger driveshafts is... Motorcraft XG-8! It's "baby blue" in color, but... no one will question your man-cred cuz it's out of sight, down under, so to speak... a 3 oz. tube (enough to do the slippy-clunky driveshaft at least 2, and some say 3 times) costs $28.xx+ at Ford Parts Counter... or $6.29 at O'Reilly... I sheet ye not. I'm about to use a modest quantity on my PVH hubs... expecting great things, lol...

Being fully synthetic, XG-8 is also safe for (most) plastics... soze Ima use some on my eh-spensive Herman Miller office chair... soon az ah ken figure out exactly where da squeak be comin' from...

What my Ranger is doing only occurs while in 4wd so I am thinking it is not the rear drive shaft.

 

[osujason]

Update, while looking at CV axles, I found the passenger side had a torn boot, grease was sprayed every where. So I'll be replacing probably both CV axles here in the next week. I am hoping that was the cause of my 4wd clunking under load. Although the torn rubber boot on the cv axle is a recent development, the clunking has been occurring for maybe a year, but I am hoping that the internals of the cv joint started going bad much longer ago, and the rubber boot tearing now was just a result of the cv axle going bad.

 

[gw33gp]

You might think I am nuts but is your A/C on when this happens?

I had something similar happen to me on a long steep gravel road one time. I thought my transfer case was going out. I could not reproduce it with hard acceleration and tried several things trying to diagnose it. I could not figure it out until one day I was climbing a hill again in 4WD and it did it again. I had the A/C on and I decide to turn the A/C off. The clunking stopped. It was the A/C cycling that was causing it. Apparently when the A/C kicked in with the engine under load already it cause the rpm to drop quickly and possibly rise again causing this clunk. I recognize it now and either turn the A/C off or just ignore it.

 

[osujason]

You might think I am nuts but is your A/C on when this happens?

I had something similar happen to me on a long steep gravel road one time. I thought my transfer case was going out. I could not reproduce it with hard acceleration and tried several things trying to diagnose it. I could not figure it out until one day I was climbing a hill again in 4WD and it did it again. I had the A/C on and I decide to turn the A/C off. The clunking stopped. It was the A/C cycling that was causing it. Apparently when the A/C kicked in with the engine under load already it cause the rpm to drop quickly and possibly rise again causing this clunk. I recognize it now and either turn the A/C off or just ignore it.

That is pretty crazy, but now that i think about it, i usually do have the a/c on so I'll test that possibility out later today. The way you described it is exactly what is happening to me. It sounds like my transfer case or something is about to break.

 

[pjtoledo]

on a non-related note, your user name looks familiar, did you used to play with Yamaha V6s?

 

[osujason]

on a non-related note, your user name looks familiar, did you used to play with Yamaha V6s?

Nope, wasn't me.

 

[osujason]

You might think I am nuts but is your A/C on when this happens?

I had something similar happen to me on a long steep gravel road one time. I thought my transfer case was going out. I could not reproduce it with hard acceleration and tried several things trying to diagnose it. I could not figure it out until one day I was climbing a hill again in 4WD and it did it again. I had the A/C on and I decide to turn the A/C off. The clunking stopped. It was the A/C cycling that was causing it. Apparently when the A/C kicked in with the engine under load already it cause the rpm to drop quickly and possibly rise again causing this clunk. I recognize it now and either turn the A/C off or just ignore it.

It still clunks when the a/c is turned off. So now I'll be looking at the CV axles this weekend.

 

[Jim Oaks]

Sounds like it's your CV axles.

 

[osujason]

Sounds like it's your CV axles.

I hope it's the CV axles at this point.

 

[osujason]

Update on the clunking in 4wd while under load:
I had the passenger CV axle with the torn boot changed out, I also noticed a ball joint was shot so I had that replaced as well. I opted not to switch out the driver side CV axle as it looked fine for now. I was confident the clunking would stop, but nope, still clunks.

So I put the Go-pro down there and what I saw was the rear diff and drive shaft as the culprit. The rear drive shaft would violently thrust upwards most likely causing the transfer case to hit the bottom of the truck. I think the root cause of this is axle wrap. I'm thinking i need to replace the leaf springs now to keep the rear diff from rotating, I would say the rotation is somewhere between 1 to 1.5 inches, its kinda hard to gauge on the Go Pro. I had already been thinking about the replacing the leaf springs because they were looking very used. My other question is what is the transfer case secured to? The frame or just transmission?