Loud pop/bang when slowing crawling up a hill?

[NJshadow93]

Today I slowly crawled up a hill to look at the suspension flex. I did it three times, once in 4 hi and twice in 4 lo. Each time I did it, I went up very slowly, and about halfway up, I heard/felt this loud pop/bang. I didn't have the CDL engaged. My first thought was CV axle binding, but didn't think that's possible when the diffs are open. Anyone else experienced this or know what the cause is?

Also, on certain occasions, if I'm driving on pavement and I accelerate slowly on an incline, I hear and feel a similar pop, just on a lesser scale.

 

[TheeMikeB]

Does it sound like it's more from flex or from the drivetrain?

Maybe you can make a video of the noise?

 

[NJshadow93]

Does it sound like it's more from flex or from the drivetrain?

Maybe you can make a video of the noise?

Sounds like drivetrain to me.

 

[TheeMikeB]

That's tough to diagnose over the web. I'd suggest trying to recreate the situation and either have yourself or someone else under or near under the truck and try and pinpoint where the sound is coming from. And as stated before try and video it.

 

[NJshadow93]

That's tough to diagnose over the web. I'd suggest trying to recreate the situation and either have yourself or someone else under or near under the truck and try and pinpoint where the sound is coming from. And as stated before try and video it.

Could it be the drive shaft? I greased the zerks in my last oil change about 700 miles ago, maybe I didn't grease them enough. I don't hear any other clicking while driving regularly, any way to check for a bad CV joint? I remember reading to check for play in the axles. Should they not budge when you shake them?

 

[having fun]

Correct, they should be solid in a way. there just like a u joint, but, on a triangle joint.

 

[NJshadow93]

Correct, they should be solid in a way. there just like a u joint, but, on a triangle joint.

Both front axles move the same amount, just a little bit, when I shake them. How do I check the U joints? Same thing, just grab and try to shake them?

 

[having fun]

U-joint, In general, yes. Little easier though since you can see them. As you grab the drive line and try to turn back and fourth, my self, I look at where the male end goes into the cap as you do it, It shouldn't have no play/ give in it.

The cv's will have a little movement, LITTLE. If that joint is bad/broken, the movement would be in that area. Most cases I have read, they are good or if broken, you wil be able to tell. Granted I haven't seen/experience this one yet.

 

[NJshadow93]

I'm hoping its just the clunk, sometimes when driving on the highway, if I take my foot off the gas but need to accelerate quickly right away, I get the clunk. I'm wondering if that's connected in any way.

 

[Stuck CAPS]

Could it be the drive shaft? I greased the zerks in my last oil change about 700 miles ago, maybe I didn't grease them enough. I don't hear any other clicking while driving regularly, any way to check for a bad CV joint? I remember reading to check for play in the axles. Should they not budge when you shake them?

Check those differentials... That's the sound I made when I blew my rear end...

 

[NJshadow93]

I'm almost certain it's the drive shaft. It feels like driveshaft clunk everyone knows, I just don't understand why it happens EVERY time I slowly crawl up that little ledge...

 

[ebg18t]

That's the sound I made when I blew my rear end...

That doesn't sound good...

 

[JB.]

Today I slowly crawled up a hill to look at the suspension flex. I did it three times, once in 4 hi and twice in 4 lo. Each time I did it, I went up very slowly, and about halfway up, I heard/felt this loud pop/bang. I didn't have the CDL engaged.

Duplicate the situation but lock the center diff and see if that changes anything. Also (separately), pull the grey plug in the front of the brake assembly to turn off ABS functions.

These are easy tests and if nothing changes, you'll at least be able to focus with more certainty on front/rear diffs, u-joints, or CVs.

 

[NJshadow93]

If a front diff was going bad, would it have symptoms? Or would it just fail? It drives normally otherwise and obviously always in 4hi.

 

[NJshadow93]

Think I figured it out, when the clunk happens, the whole muffler shifts toward the back about a half inch. I could barely hear the noise from the outside, until my mom (who I had driving the truck up the hill) pointed out when it made the clunk. I'll try to get a video up later, I'm having a buddy stop by in a little while to drive it up the hill a few more times (my mom got impatient haha)

 

[NJshadow93]

Here's the video. You may have to watch it a few times but you can definitely see the exhaust shift about a half inch if you look close enough.

 

[Greydog]

Yup, saw it skip just a bit. Is that a loose exhaust hanger issue or motor mounts?

 

[NJshadow93]

Yup, saw it skip just a bit. Is that a loose exhaust hanger issue or motor mounts?

I checked all the hangers and they look good. I was thinking it was just shifting on the rubber mounts? Is there any way to check the motor mounts myself?

 

[Greydog]

Hmm, I'm not sure how to check them. Can you identify what it's hitting or is it just wiggling around?

 

[Greydog]

Could it be one of the pipe joints is not welded and the clamp loosened up so the pipe is slipping forward/backward?