Strange noice from drive train?

[jlord]

Starting around 5K, my truck started making a strange noise when starting from a stop, or most noticeably, when accelerating after letting off for a short amount of time. It sounds like the u-joint is loose, and slapping against something when it engages again.



The local dealer listened to it, decided it was a bad rear differential, then proceed to replace the ENTIRE rear end. When I went to pick it up, it was still making the exact same noise. Now they are not sure what it is, and want to have it for a couple of days to look into it.



The scary thing is that when they worked on it the first time, they told me that they had never seen one like that before, and weren't sure what to do with it, so they were just going to replace the whole thing. Now they are scratching their heads.



Anyone heard this noise on their truck? I drove a new one while I was over there, and heard nothing.

 

[Bunn]

Whoa, They replaced the rear end under warranty with the bigger tires on there?

 

[GLolas]

Can you describe the noise a little more?



I have heard a noise under mine every once in while. Mostly when I let off on it and its decelerating. It is very, very slight and kind of sounds the same as when the AC compressor engages and disengages but not as lound.

 

[jlord]

It is pretty loud, and easily heard over the sound of normal driving. It sounds like my old Ford F100 did when the u-joint has slack in it. Makes a metal clang. If your going forward, then stop, then go in reverse, I will hear it. Or, if your coasting down a hill, get to the bottom, then accelerate, you will hear it then as well.

 

[rashwor]

I don't know...

but it sounds like drive line slack some where between the engine and the wheels. My first thought would be the differential since there have been some issues with those. But since you just got a new one, that is probably not it. Might check the u-joints for slack. Could it be the drive shaft carrier bearing?



Just some thoughts on what to look for.



You might try to jack up the back end and put it in Neutral (might try it in gear as well) without the truck running and see what you can find. If you find it, stick the dealer's nose to it so he can see it.

 

[RAMINSPEED]

It sounds like it could be the slip yoke at the tail of the transfer case. The spines of the tail shaft wear with the transfer case and they will clank when you accelerate of reverse, etc. My old dodge did it but it eventually went away.

 

[rbattelle]

Sounds to me exactly like a bad U-joint. At least, the way you describe it is how I would describe every vehicle I have ever owned when a U-joint was bad.

 

[Prairie Dog]

Mine makes the noise you describe. It's got 18000 now and has done it it's entire life, especially when towing. I guess I was hoping it's normal.

 

[Tomeygun]

I had a customer come in with this situation, It would make the sound when he left from a stop, (6-spd), or if he lugged it in third and gave it throttle, it would go away after 1500 rpms or so, I figure something wrong with the pilot injection, or a puddling injector, so has this problem been fixed??

 

[Tomeygun]

just a little update for every:



concerning my customer with the loud noise from idle and stopped by 1600 rpms, It sounds like a clutch/u-joint prob. ,



Would you believe it was a LOOSE INJECTOR? the high pressure injector would move and create sound when it moved...



wierd huh? and the mechanic said all were tight to spec, but the #6 one was more loose, now the truck runs perfect through all RPMS, crazy!