Drive line sound, is it a transfer case?

[MojaveMadMan]

Hey all,

Hoping some of you masters can help me out on this one. Went on a long multi day off road trip. Put 1200 miles on the 4runner, 400 of which were off road. Didn't notice the sound until I got home.

So it is a slight clunking sound the ticks faster as the 4runner goes faster. BUT it only makes the sound when driving, and not with RPM. The sound only is present under load too, so if I get moving and let off the throttle the sound goes away. Hit the gas and it comes back.

Things I have figured so far:

- U-joints. I took a pry bar to my u-joints with another inclined Toyota guy. We tried to move them all around and didn't seem to find anything that looked like it needed attention.

- E locker on and off, still get the same noise

- 4wd hi, noise goes away

- 4wd low. noise goes away

- Transfer case in Neutral, transmission in Drive, no noise.

- Another observation, the front drive shaft is spinning. I was under the impression that they were not supposed to spin when in 2wd?

I was thinking about taking the front drive shaft off to see if the sound goes away. If the sound goes away that leads me to believe it may be something with the front ADD which is spinning the front drive shaft and may be causing the transfer case to make those sounds... Haven't had a chance to mess with it but if someone knows something that may help that would be great!

Thanks all for any help!!!!!

 

[JayRolla]

Hey all,

Hoping some of you masters can help me out on this one. Went on a long multi day off road trip. Put 1200 miles on the 4runner, 400 of which were off road. Didn't notice the sound until I got home.

So it is a slight clunking sound the ticks faster as the 4runner goes faster. BUT it only makes the sound when driving, and not with RPM. The sound only is present under load too, so if I get moving and let off the throttle the sound goes away. Hit the gas and it comes back.

Things I have figured so far:

- U-joints. I took a pry bar to my u-joints with another inclined Toyota guy. We tried to move them all around and didn't seem to find anything that looked like it needed attention.

- E locker on and off, still get the same noise

- 4wd hi, noise goes away

- 4wd low. noise goes away

- Transfer case in Neutral, transmission in Drive, no noise.

- Another observation, the front drive shaft is spinning. I was under the impression that they were not supposed to spin when in 2wd?

I was thinking about taking the front drive shaft off to see if the sound goes away. If the sound goes away that leads me to believe it may be something with the front ADD which is spinning the front drive shaft and may be causing the transfer case to make those sounds... Haven't had a chance to mess with it but if someone knows something that may help that would be great!

Thanks all for any help!!!!!

Had same issue, u joints felt solid. I lifted her up, put her in gear and went under while she was running in drive and I could hear it coming from rear of xcase/front of driveshaft.

Ended up being failed double cardan joint on my driveshaft. $25 junkyard shaft and issue is fixed. Just listen and make sure where its coming from. I shot some wd40 in the cardan joint and it seemed to change the sound making me believe that was issue.

 

[4RunnerChaos]

Had same issue, u joints felt solid. I lifted her up, put her in gear and went under while she was running in drive and I could hear it coming from rear of xcase/front of driveshaft.

Ended up being failed double cardan joint on my driveshaft. $25 junkyard shaft and issue is fixed. Just listen and make sure where its coming from. I shot some wd40 in the cardan joint and it seemed to change the sound making me believe that was issue.

I'm starting to believe this is a kind of common problem. Mine does the same thing as yours. I talked to a guy who rebuilt drive lines for a living. He said it's not uncommon for the trucks with or drive shaft to have failed like that.

As for your front drive shaft it's normal that it spins. It is NOT spinning because of the transfer case, it is spinning because the front wheels are still connected to it.
If you put it in four jack stands and in drive, the front shaft won't spin.

 

[MojaveMadMan]

Ok so it really sounds like I need to give the double cardin another look. I had a friend over and we pried on all of those joints real good. But I could see how it's just enough to make noise under drive but not be a sloppy mess...

 

[techno]

- Another observation, the front drive shaft is spinning. I was under the impression that they were not supposed to spin when in 2wd?

Correct, it should not spin. I would certainly investigate this symptom more.

 

[MojaveMadMan]

So I have t had much time to really dig into this thing yet... I did jack up the front wheels today and spun the tires. Each wheel spins independent, not together so I think I can rule out the ADD. If the ADD was not working correctly both wheels would spin if I understand it correctly.

I want to believe it's the double cardon joint but that doesn't explain why the sound goes away when in 4wd. I'll try it again to make sure, but if that is the case then it's not the rear drive shaft. So this points me back to transfer case...

Oh and I drove it on the freeway for the first time yesterday. I get a serious vibration under load I can feel on the floor and even in the pedal. No "ting" sound like a u-joint. More of a deep sound...

 

[techno]

Replaced the rear engine mount on the weekend. Sure enough it was broken. If you don't know what you're looking at, the rubber parts should be connected to both the metal plates.

My drive line clunking is gone.