Diff Or Not To Diff?

[GunstarZero]

Hi folks,

I have been having a tapping sound when I drive, I can't hear it when I accelerate but when I take my foot off it speeds and slows dependant on my speed.

Today I was driving and there was a huge bang and after it has a slight metal on metal/dragging sound.

I dropped in at a local garage who said my diff is dead (my diff is a little wet on the outside) and said my link arms have too much play in. There gave a ridiculous quote (500 for used diff and labour + 100 for link arms)

I firstly think the pricing is crazy given a used diff is about £60. I also don't think the symptoms sound like a diff. Does anyone have any ideas?

note: 2001 e46 320 auto

Thanks in advance!

[BimmerBreaker]

If you don't think it sounds like a diff, what do you think it does sound like?

[GunstarZero]

note: metal dragging sound has gone now.

I'm not an expert by any stretch. But given I have had 2 sets of wishbones on the front in the past 5 years I would assume it's suspension related?

I'm purely guessing (much like the mechanics!) I just wondered if anyone else had similar at some point?

[ELVA164]

Sounds like the diff.

The noise you heard initially could have been the pinion bearing going bad, followed by the "bang" of the pinion either flopping around and annihilating the ring gear, or the pinion seizing on the bearing and causing the same results. Can you turn the rear wheels and watch the driveshaft turn?

[GunstarZero]

Sounds like the diff.

The noise you heard initially could have been the pinion bearing going bad, followed by the "bang" of the pinion either flopping around and annihilating the ring gear, or the pinion seizing on the bearing and causing the same results. Can you turn the rear wheels and watch the driveshaft turn?

Yeah wheels turn fine, driveshaft moves smoothly. No noise from it when wheels are spun on a ramp (by hand), only time I hear anything is when I take my foot off the accelerator.

[ryanc528]

Have you pulled the diff plug and checked for metal in the fluid? That would be a pretty clear indicator if it the diff..

[ELVA164]

Since the sound changes with vehicle speed, it's either in the drivetrain or the wheel bearings. A "bang" in a wheel bearing would mean one of your wheels wouldn't be turning anymore. I'd imagine anything else that made a bang would make some sort of noise even at low speeds...the diff and the gearbox would experience lash which could cause noise, or maybe a u-joint in the driveshaft or CV joint in an axle.

[GunstarZero]

Have you pulled the diff plug and checked for metal in the fluid? That would be a pretty clear indicator if it the diff..

I haven't yet. I'm waiting for my bro to lend a hand next week.

Since the sound changes with vehicle speed, it's either in the drivetrain or the wheel bearings. A "bang" in a wheel bearing would mean one of your wheels wouldn't be turning anymore. I'd imagine anything else that made a bang would make some sort of noise even at low speeds...the diff and the gearbox would experience lash which could cause noise, or maybe a u-joint in the driveshaft or CV joint in an axle.

Wheels spinning fine, no noise at all from those. I thought driveshaft might be an option too, or some kind of bearing.

[BimmerBreaker]

If it isnt immediately visible from somewhere underneath the car or by poking around, I wouldn't rule out the diff. Just because it seems fine without load doesn't mean when there is load from the engine that it will be ok.

[GunstarZero]

If it isnt immediately visible from somewhere underneath the car or by poking around, I wouldn't rule out the diff. Just because it seems fine without load doesn't mean when there is load from the engine that it will be ok.

Oh yeah of course I'm open to anything really. It's just the varied opinions received making me uncertain.

[BigC0605]

OP, did you find the issue...My car has been doing the same noise for a couple months now and its driving me crazy. Mine only happens when I reverse and when I turn, once I go straight the noise goes away. Any update yet?