Grinding from front of car

[miloh]

My 05 3.0i auto has been making a grinding noise on occasion for three years or so whenever it’s cold and you put it in drive. It only lasts about 20-30 seconds. Only happens when moving.

On some occasions it will make a sound like when you wet your finger and rub a drum head: 1:21 in this video. https://youtu.be/_AvBqIH-Eus?si=4733g9se98ku0vMQ When this happens power is reduced for about 5 seconds until the sound stops (only ever lasts about 5 seconds).

I thought it could’ve been something pulley related on the front of the engine and over the course of 6 months replaced almost everything, except the power steering pump and A/C compressor. I had a leaky power steering reservoir that dumped crap everywhere. My alternator needed replacing because it’s bearing was destroyed from the ps fluid. The bearings of almost everything were old anyway so I thought, maybe a bearing is really bad on something.

The transmission has been completely fine. Not once has it lagged switching from park to reverse. When it’s cold it hasn’t ever had problems switching gears or holding for too long. It’s never been serviced.

I just had both diff fluids replaced and the transfer case fluid swapped, same issue this morning.

My PS pump still has a lot of gunk around it, as it’s so hard to remove that crap. The AC compressor is a non OEM one from 2018 and I haven’t had any issues with it.

It’s not a continuous grind, it’s intermittent once you accelerate. I can feel it in the seat. It’s gone completely after 30 seconds max and it’s been there for three years… I replaced the TC actuator gear around 3 years ago when it threw a 4x4 code. I’m at a loss of what it could be. Maybe related to that? I read about the chains expanding, i’m at 180,000

[andrewwynn]

That sounds like DSC erroneously kicking in (clue is reduced power).

I had a wss lose than gave me a very similar sound/sensation.

What scanning solution do you have? Can you realtime read your wheel surf sensors?

[wpoll]

Did this issue show up around the time you replace the actuator gear? Just askin'...

Also, when you replaced the fluid in the Xdrive (transfer case) did you perform the required reset/adaptation? This requires BMW-specific software/hardware to do (BMW DIS, BMW ISTA-D or a Foxwell scanner).

And as andrewwynn has asked, are you able to scan for codes etc?

[X5chemist]

Sticky caliper?

[miloh]

Originally Posted by andrewwynn

That sounds like DSC erroneously kicking in (clue is reduced power).

I had a wss lose than gave me a very similar sound/sensation.

What scanning solution do you have? Can you realtime read your wheel surf sensors?

I do, I have a laptop with INPA/ISTA loaded and have used it in the past. I won't be able to do this for a few days. This was an issue this morning, but I just had my rear subframe welded along with fresh bushings and new lemforder parts (the FCP kit) at a shop. They outsourced their alignment to a firestone shop and the steering wheel slipped 2-3 degrees off over Fri-Mon so it's back there to determine the issue and re align it.

Originally Posted by wpoll

Did this issue show up around the time you replace the actuator gear? Just askin'...

Also, when you replaced the fluid in the Xdrive (transfer case) did you perform the required reset/adaptation? This requires BMW-specific software/hardware to do (BMW DIS, BMW ISTA-D or a Foxwell scanner).

And as andrewwynn has asked, are you able to scan for codes etc?

I don't think this appeared when I did the actuator gear, I checked my photos and apparently it was May 2022 that I replaced the gear. It's made this noise it since pre-pandemic times.

I did not check if the shop that serviced my diff/tc fluids did the reset adaptations. I just called and left a message, they closed 15 minutes ago. My TC drain bolt was stripped so I had them cut it and break it loose. Whoever serviced it in the past used an air gun and didn't torque it.

Originally Posted by X5chemist

Sticky caliper?

I don't know how to determine that.. I had a rotational grind forever on my car from the passenger front side and determined it was a bent disc protector plate thingy. I bent it a little bit and it stopped making that sound. In the past when I've done brake service I haven't thoroughly cleaned the caliper pistons. I cleaned it, but not well enough to be proud of it.

For more information about how the grind sounds/feels: it's inconsistent when it happens. It's not a rotational or speed-increasing sound/feeling through the chassis. It's erratic like if someone threw something into a gear by hand at their discretion, but frequent. LOL.

It sounds as if it comes from the center in front of me, which made me assume pulleys as it sounded far enough forward that it wasn't the transmission/TC.

The drum-finger-rub sound I described that happens simultaneously with the grind, that sound is consistent. It's so shortlived. It's pitched, starts a bit higher, goes to a lower pitch and stays there, then pitches back up and disappears.

I haven't had the balls to give it the beans when this is happening, so the reduced power I mentioned is inferred by my experience lightly tapping the gas and maybe not experiencing the same amount of power as I would expect.. I'll back out of a driveway onto a residential street, experience it for 10-15 seconds, then by the time I come to a stop and accelerate again to merge onto a road it's gone.

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EDIT: I forgot to mention, I appreciate y'all so much. I love this car to death, I'm still rocking no roof 2 years after replacing my pano tray. idgaf it's such a great drive.

[ahlem]

I had the same issue. The wheel speed sensor on one of the wheels had accumulated enough iron filings to interrupt the signal occasionally. I took off all the sensors and stuck a bamboo skewer with a thin strip of non metallic Scotch Brite with some evaporative cleaner on it. I rotated the rotors and rubbed off the remaining filings that were stuck in there and blew compressed air down the holes while I rotated the rotors further. I used a white cloth initially to see how much gunk was on the sensor contact faces. it solved the problem for me. In my case it was like one of the brakes had locked up. Very annoying.