NEED HELP!! Diagnosing loose U-Joints and oil leak (Video provided)?

[MartyMcFLy]

2001 suburban 2500 4x4 6.0

When I shift into reverse, I hear a slight thud with a split second hesitation. Also, when I take off, I hear a slight tinny grinding noise which goes away after hitting 10mph. What could it be?

I also have this oil leak. It leaks a palm sized puddle every two days or so. I’m wondering if it is coming from the crank case. Any ideas? Much appreciated!

 

[swathdiver]

Don't think there is anything wrong with the driveshaft or TC output shaft. Oil leak could be coming from up higher, maybe the valve cover? Don't have much experience with this motor and oil leaks so hard to say if it is rear main seal. Others will chime in with more knowledge than me.

 

[Erickk120]

Honestly the np246 is a clunky pos tcase to begin with, I have yet to find a truck with one that doesnt make a little clunk, ds seems fine, check the ujoints with a little pry bar. I would be more concerned about the grind you are hearing, and trying to locate it. As far as oil leaks well, its a vortec, and there is a laundry list of gaskets that could be the culprit without examining it in more detail. I'm sure we all are familiar with those here in the forums.

 

[MartyMcFLy]

It’s my guess that the clunk when shifting from reverse to drive and vice versa comes from the play in that shaft that I was grabbing. Not sure if it’s a huge deal or not, but I don’t want to come across a catastrophic failure in the near future if I continue to leave it as is.

 

[Erickk120]

Does it sound as bad as mine? This is mine going from Drive to reverse and vice versa. If it isn't as bad I wouldn't worry about it for the time being.

 

[MartyMcFLy]

Does it sound as bad as mine? This is mine going from Drive to reverse and vice versa. If it isn't as bad I wouldn't worry about it for the time being.

Wow, that’s pretty loud. I haven’t heard it from outside, but inside it’s not that loud. Just a slight clunk, but I can feel the engagement and disengagement.

 

[wjburken]

Have you checked the condition of the fluid in your differentials? Transfer Case? That grinding sound, as someone else mentioned, would have me worried. Can you put the vehicle up on jack stands safely so all 4 tires are off the ground and have some one shift the truck into gear and stuff while you listen from the outside?

 

[MartyMcFLy]

Have you checked the condition of the fluid in your differentials? Transfer Case? That grinding sound, as someone else mentioned, would have me worried. Can you put the vehicle up on jack stands safely so all 4 tires are off the ground and have some one shift the truck into gear and stuff while you listen from the outside?

I haven't tried that yet. The fluids I haven't checked either besides oil and transmission fluid.

That would be a good idea. I need to get some jack stands and a volunteer to analyze from underneath the vehicle.

 

[Fless]

As @wjburken recommended, check your diff and T/C fluids sooner than later, and don't wait for the jack stands. If you have the NP246 T/C and someone used transmission fluid in it, well, I hope not.

My NP246 doesn't clunk at all until I shift it into 4LOW, and hardly makes a sound when the propshafts aren't in place (as in when we were testing for noise on mine).

 

[Erickk120]

As @wjburken recommended, check your diff and T/C fluids sooner than later, and don't wait for the jack stands. If you have the NP246 T/C and someone used transmission fluid in it, well, I hope not.

My NP246 doesn't clunk at all until I shift it into 4LOW, and hardly makes a sound when the propshafts aren't in place (as in when we were testing for noise on mine).

Thanks for actually putting it out there, mine had transmission fluid for who knows how long, til I bought it and replaced it, but it was prob too late and here I'm, I wonder how it affects the life of it, or clutches in the long run.