asking for help/ideas identifying a noise around LR wheel

Hi all, I've had my 91 348 TS for about 3 months now. I've been reading and learning as much as I can on the site, and I've already solved a few minor issues with the information I've found. Yesterday though, I took the car out and noticed an intermittent noise that sounds like it's coming from LR wheel area. I took it back out today and I managed to capture a prolonged episode with my phone stuck out the window just after it started. sorry for the wind noise. This noise is not constant, and you may be able to hear at about 16 seconds it stops but there is no input from me to make it stop that I can tell.

https://www.youtube.com/watch?v=RbHcFzkw8Mg

It comes and goes, and does not appear to have anything to do with speed. I will hear it at 20mph and yesterday I noticed it at 60 mph. Because of the nature of it and the sound, I don't think it's the bearings or CV joints, but I don't know. the CV boots look good on that side, and the car just had a major less than a year ago. The CV boots on the right side were replaced at that time. It almost sounds like something is dragging, ebrake maybe? I should have some time this weekend to pull the wheel off and take a look. In the meantime I was hoping that the sound in the video may give an indication of what it could be. thanks!

 

thanks, the ebrake is released. At least the light is not on. It appears to work as it should. My ABS also appears fine as well, lights activate on the first position of ignition. I hear and feel the pump activate and then the lights go out.

My thought about the ebrake was it sounds like something is catching/dragging. The more I listen to the video, I'm starting to wonder about possibly a belt. The car just had a major last year with cam belt, hill tensioners, new cam seals, new alternator and ac belts. But they water pump wasn't changed out. It's got me wondering if I was just thinking the sound was on the left side because that's where I heard it.

I plan on doing as you suggested, I'll jack it up, check for play and see how the wheels turn. It's hard to pin down because it is intermittent, and doesn't seem to happen at idle, at least not so far. I give the car at least 15 mins to come up to temp and have not heard during that time.

 

Cool thanks! I should have time to at least do the ebrake test tomorrow.

 

thanks for all of the helpful suggestions. I'm going to try them all. I've been retracing my steps and my neighborhood is full of construction right now, I'm wondering if it's possibly something as simple as some dirt or mud that got trapped in my braking mechanism. I had to cross through some fresh mud tracks left by a pickup to get out of the neighborhood Wednesday, that was about 5 minutes before I first noticed the noise.

On the other hand, I have the last 8 years and ~4700 miles of history on the car, and there has been no brake maintenance in those records. The PPI showed passable numbers, but I don't have that in front of me right now. Either way a good inspection is in order.

Actually, I really don't know. I live in an area with very flat terrain, there are no hills or even inclines that would have caused me to test the ebrake through normal use. Most of the time the car is in its garage stall, I leave in first with the ebrake disengaged. The only time I engage the ebrake is to let it idle while warming up. That could be something else I could try: set the hand brake and see how will it holds while pushing on the car.

thanks again for all of the ideas! I'll report back with results as I get them.

 

yep, that's part of my plan. I'm hoping I can recreate the sound or something similar in a controlled setting so I can determine what it is.

thanks! with all of the experience on the forum I was hoping somebody might be able to hear something familiar in the bad video I took of it. So far, I've never heard it at idle, so it indeed leads me to something related to wheels/bearings/CV/brakes.

I am going to try to find some time this afternoon to get the rear end off the ground and start looking around.

 

Early last week I pulled the LR wheel off and did a quick inspection of the rotor and pads on that side. I didn't find much at that point, I hit the whole thing with brakeleen and put it back together. I went for a drive a day or 2 later and was pleased that after several miles, no odd noises. then on my way home I heard a couple of short chirps, same noise but not nearly as bad as it was the last time.

This morning I've finally had some time to tear into a little more to try to find the source of the noise. I have the calipers, rotor, and parking brake assembly off the left rear wheel. Turning the shaft by hand doesn't produce any noise, but I can't turn it very fast by hand. At any rate I don't hear any kind grinding or clicking in the hub face or CV joint. I don't observe any play in the hub face. Things seem to be ok from that standpoint. The shoes on the parking brake look pretty well worn so now that I have them off on the left side I'm going to order a full set for both sides. On the interior side of the left rotor there are some obvious signs of debris getting in between the pads and rotors, and one thing that has me concerned are the dark, flat spots on the outer edge across from each other. The outside of the rotor looks normal. The pads look fine all around. So based on this...what would you guys do next? Does the rotor look done? Any thoughts on the dark spots? The certainly look like hot spots, but the fact that there are 2 directly across from each other is interesting. I wonder if these could be my noise, and if so is there a deeper root cause?
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I just wanted to update in case my lesson helps anybody...I made things much more complicated than they needed to be. I am nearly certain the louder noises I was hearing was debris getting trapped between my ebrake shoes and the drum. Even though the light would extinguish on the dash when releasing ebrake, I could still hear some resistance from the shoes while turning the rotor with the caliper off. Also, there were visible tracks inside the tophat where I could see it had been dragging. This was also causing a constant squeaking that I could hear when passing close to anything on the left side that would echo it back. I would guess it's been doing this on and off for quite a while by the looks of the tracks. There was ALOT of junk in there too, rust flakes and so forth. Those were making the louder noises. I replaced the rotors and pads in the rear and still had the issue, so in a moment of frustration and epiphany I yanked the hell out of the ebrake to release it and voila, no more dragging, no more noise. So the initial discussions about the ebrake was the path I should have followed, but it doesn't hurt to have shiny new brake disks and pads. Just went out for a nice drive and the only sound was engine tone. Now I need to see about properly adjusting things so I don't have feel like I'm about to rip the cable through the floor to release the ebrake.

thanks for all of the help and suggestions!

 

thanks, Jeff. I should have mentioned that your write up was very helpful to me in digging into this so far. I was going to go back to your info when I go back in to make the adjustments. The information and pictures you provided was extremely valuable to me in learning about how the ebrake works and how to break down, inspect and reassemble the hardware. I did that on both sides and cleaned them thoroughly so they look as good as new. The shoes still plenty of material even with the occasional friction they have endured.