Crunching noise from transfer case happend 3 times to wifey today

[BMC530i]

Car "crunched" three times this morning while wife was driving, it drives ok now but i think i can hear a faint grinding sound coming from under the car while driving next to wall

It happened to me once last year while driving, crunching sounds from under the car, and vehicle slowed down on its own. I immediately shut the engine off and after restart i drove home without any issues. Whats options do i have now? The X5 3.0 has 74K and I'm suspecting the chain is getting stretched. I honestly feel that I'm driving on borrowed time here from now on.

Should i go ahead and order re manufactured NV 125 case (whats the best place to find one) or should I buy replacement chain and attempt a DIY?

Thanks in advance

[JCL]

Check the chain stretch first, then tear it down or have it torn down. After diagnosing it, I would do the chain and not purchase a reman transfer case.

[rcelik]

I wouldn't worry about it. My 2004 X5 3.0 has 152,000 miles and it has been making the same noise since at least 80k.
It only makes the noise during heavy acceleration.

[Jedi]

I did the DIY route. I ordered the chain from Cobra Transmissions, and had a friend help me. It took us about 9 hours. I wish we had dropped the exhaust from the start, but I was being stubborn. The chain swap itself is not that hard, and putting everything back together went pretty quickly.

Previously, I experienced a "clacking" sound under heavy acceleration (and it worsened to just mild acceleration). The new chain is great... $120 in parts later... one of the cheapest fixes I've ever done. Accelerates like a new car now!!

[mysweetx5]

Wow congratulation jedi!
Your description gives me so much confidence specially with the outcome
of your chain replacement. However I thought about performing this heavy
job too all by myself, because I've been having this loud noise when
accelerate specially at high RPM also while making a quick take off.

Although! some described it to be much difficult than changing trans. Fluid
which I did 5 months ago. but the way you described your experience
doing it + the outcome of it made me feel like to take a try. So now,
I wonder how was you able to replace the chain without dropping the
entire transfer case down? I wish you only have to dropp down one side of the shaft, remove all the bolts around side of the transfer case to replace
the chain.

wish you could give me some more tips on that because dropping the entire
transfer case down will not be on my project, the fact that I've been doing
all of my heavy jobs on the side street, or at one autozone parking lot near me. Because I don't have a private driveway like you folks, I live in NYC
where parking space is cocaine out here.

01 X5 4.4i

[mysweetx5]

mine doesn't make a clacking noise, instead it sounds like a jet engine
under the car and seems taking a delay to picking up speed. But at high
speed, when pressing the gas pedal the loud noise seems to be heard
very low and I can't barely hear it at this point.

[racingbmwm3]

Originally Posted by mysweetx5

mine doesn't make a clacking noise, instead it sounds like a jet engine
under the car and seems taking a delay to picking up speed. But at high
speed, when pressing the gas pedal the loud noise seems to be heard
very low and I can't barely hear it at this point.

The Jet Engine sound is usually caused by a bad fan clutch. Inspect your fan right away and if it is causing that sound, replace it now! The $150 now is much cheaper than all the damage caused by the exploding fan blades.