Your best guess: Intermittent grinding sounds

[laffycaffi]

So I forgot about this since I haven't driven in a while, but I keep getting intermittent grinding sounds from underneath my feet... here's what I know. What are your best guesses:

1. happens regardless of speed. Fast or slow.
2. Nothing in particular seems to trigger it. Not turning, not braking, not accellerating.
3. It happens when I coast out of gear. And also coasting with the ignition off.
4. It's not a long grinding sound. a short, but definitely audible sound.
5. It appears to be getting worse (more frequent, more loud)
6. The sound often feels like it's right under my feet. But sometimes I feel like it's coming from passenger side.

Any ideas? I'm hoping it's bearings and not something like transmission.

[Viperwolf1]

My guess is either a bad u-joint/cv or rear axle bearings.

[ZOSO]

I'd second the rear axle bearings. I had the same thing. I pulled the t case twice to see if i messed something up(freshly rebuilt) and in the end I lost a rear axle bearing.

[laffycaffi]

I'm suspicious that it's my transmission.

I reached my pinkie into the transmission fill plug and didn't touch any fluid.

Didn't see a drain plug, so I assume it's linked to the transfer case. Unscrewed that drain plug and it had a bit dribbling out...

[Rox Crusher]

You can usually see / feel a bad u-joint so easy to confirm or eliminate that.

Rear axle bearings can be checked by lifting wheel off ground and checking for slop / excessive movement.

A rear axle bearing failure can be pretty costly if the wheel and axle depart the housing while driving.

[Justin]

Trans and transfer case are separate. What transmission are you running? If there's no oil in the tcase you could have nuked a bearing in that. I'd fill it back up and see what happens.

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[Gunnibronco]

I'm suspicious that it's my transmission.

I reached my pinkie into the transmission fill plug and didn't touch any fluid.

Didn't see a drain plug, so I assume it's linked to the transfer case. Unscrewed that drain plug and it had a bit dribbling out...

I suppose the trans could leak out the rear seal & into the t-case, but the t-case would then be over full & it wouldn't just dribble out. Refill the trans and if it's leaking it should become obvious.

Check the easy stuff first, u-joints. Taking the 9" apart & pulling axles isn't hard either. With the axles & center section out, it should be pretty easy to inspect & ID a problem. Like Rox said, a rear end failure could get expensive or worse. It's worth looking things over before a catastrophic failure.

[laffycaffi]

You can usually see / feel a bad u-joint so easy to confirm or eliminate that.

Rear axle bearings can be checked by lifting wheel off ground and checking for slop / excessive movement.

A rear axle bearing failure can be pretty costly if the wheel and axle depart the housing while driving.

I just spent a ton of time replacing bushings, and installing a 2.5" lift (like, last week) and spent plenty of time messing with the axles. I feel confident that all u-joints and bearings are solid.

I'm thinking it feels like there's something in the transmission - maybe a bearing or shard of metal floating around that gets caught up in the gearing. I'm going to drain it and see what I find.

I'm nervous. I just spent all this time on the bronco. I don't want to find that my transmission is on its way out. :/

[laffycaffi]

Another quick thought - depending on what I find - if I do find a shard of metal in my transmission fluid, and I'm still shifting fine in all gears), what are the odds I can refill and just keep driving. I'm sure the answer is that it's a ticking time bomb but maybe I can get lucky.

Timing is frustrating while being on the cusp of summertime!

[Gunnibronco]

What transmission are you running?

[laffycaffi]

3sp manual 302

[laffycaffi]

(stock)

[phyler]

Those things are pretty bullet proof. Drain and refill. Worse case, ask here and someone will probably be able to give you a working one for cheap/free. You can always put the t-case in neutral and then run through the gears to see if you can hear it.

[Eck]

I have one sitting in my shed you can have-- would actually love for you to take it. It was running well when I pulled it for my ZF.


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[laffycaffi]

Thanks for the offer. If it turns up that it needs replacing I def take you up!

So I drained the transmission fluid today and yep it was low. Not even a quart came out but no metal that I could tell.

It just kind of dribbled out though. Wasn't like a heavy stream which makes me wonder if there's something bouncing around in there and maybe was creating some blockage as it was draining. Not sure.

But I'll fill it up tomorrow and pray that it just needed to be filled.

[Rox Crusher]

what did the gear oil that came out look like ?

[laffycaffi]

what did the gear oil that came out look like ?

Like this

[laffycaffi]

Also I checked the rear axle again. I think it's good. No play, and the wheels are on solid, however I did notice a little play from rotating the wheels from one side to the other but I dion't feel this is abnormal. Still would love to hear if you think this is not good. https://youtu.be/2EItqGCwY-I

[laffycaffi]

I refilled transmission fluid and went for a drive. Still getting that sound.

Came home and put the front axle on jack stands and gave it a spin with my hand. Solid and nice and quiet.

Then I put the rear on the stands. Not as quiet. Sounded like metal rubbing on metal somewhere, like a dull, but quiet rumbling sound. However the wheels are on solid. No play when I try to rock them back and forth.

Anyone in the springs willing to give it a listen? I'm seriously at a loss.

[Justin]

Where are you located? Sounds like a wheel bearing. You won't automatically be able to feel any play.

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[laffycaffi]

Where are you located? Sounds like a wheel bearing. You won't automatically be able to feel any play.

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