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Squeaky noise when cold

Discussion in 'E39 (1997-2003)' started by kearnsclan, Jan 12, 2010.

    kearnsclan guest

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    540i 6 speed 2001. I noted lately a squeaky noise from what sounds like my front end for the first 10-15 miles when first driving in the morning. Sounds like a hamster on his treadmill....squeak....squeak.... High pitched and without vibration or grinding noise. Not related to engine RPM's, clutch in or out. Squeak is related to speed. Hard to hear below 10 mph or above 40 mph. Then goes away, seemingly after whatever it is warms up. Only to reoccur after cooling off.
    Recently took a 700 mile round trip on interstate wo any noise at highway speeds or problems
    could this be an early front wheel bearing problem? Any other thoughts?
    thanks!!
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    tiFreak

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    might be a wheel bearing, could be brakes too

    kearnsclan guest

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    Squeaky when cold

    Thanks for the tip. I had rear pads and rotors changed about 3 months back. Maybe noise is from the rear rather than front? Have noted that with quick & go application of brakes the noise seems to quit and restart.
    I will ck out this lead. BTW...84k miles on the 540i,

    Arash2002tii guest

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    Could be a loose belt maybe?

    kearnsclan guest

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    squeaky when cold

    I did not think squeak could be a loose serpentine belt, as noise is not RPM related. Squeak cycle and rhythm seems to be related to forward motion.....faster moving & faster squeak cycle. Slowing to stop, the squeak cycle slows also. Sounds like related to wheels, but could be wrong here.

    thanks for thinking with me on this!!
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    tiFreak

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    I wonder if it could be a caliper piston that's not retracting all the way making the brakes drag slightly, hard telling without seeing the car though

    kearnsclan guest

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    Squeaky when cold

    Thanks for the thinking on this.....

    Will follow the lead of brakes too. Noise sounds like a 'squealer' on brakes on my old Acura.

    Stay tuned for more symptoms as they occur.....

    thanks guys !!!

    Arash2002tii guest

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    Sorry didn't see that in your original post. :eek:
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    Louis

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    Squeaky noise

    If it's vehicle speed dependent and not engine speed dependent it has to be at a wheel or something connected directly to the wheel, like rear half-shafts, diff or driveshaft. The odds are against it being one of the last 3, much more likely something on the wheel or connected directly to the wheel. Given that it seems to go away after driving a while I'd guess brakes.

    Does the sound change as you apply the brakes, either lighly or hard? If so, likely brake pads. Does it change depending on whether you're accelerating, decelerating or running at constant speed? If so, likely a wheel bearing. If none of the above it could be something is rubbing against the brake rotor. You don't say where you're located but especially in snowy conditions the backing plates behind the brake rotors can be pushed in and will make light contact with the back side of the rotor. The fix is easy, just push or pull it away from the rotor, the spacing isn't critical.

    FWIW, high performance brake pads sometimes squeal like stuffed pigs when they're working their best. Those of us that race have long since learned to ignore brake pad noise, we just check to see if they still have any lining left!

    In any event, road speed noise problems are usually cheaper to fix than most engine speed noise problems.

    Good luck.
    Louis
    Original owner of a 2000 5-series

    kearnsclan guest

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    squealing noise when cold..

    Thanks to everyone that thought with me on this....

    NEWS FLASH ON NEW INFO.....

    Putting all the info together and with most recent info from Louis, I am reminded that I may have left out an important piece of the puzzle in diagnosising this noise.

    Recently had my brake fluid flushed. Cannont be sure, but maybe before the noise began....

    Question.....could brake fluid contamination on the pads cause such noise?? If so, would removing the pads, scuffing them with sandpaper & cleaning the rotor with brake cleaning spray be of any help????

    thanks again to all....
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    Louis

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    Squeaky noise

    Before I started pulling things apart I'd examine the brake rotor to see if there is any evidence of something rubbing it. I'd look for an unusual groove in the surface, shiny edge, etc. It isn't unheard of having a pebble or other item get between the rotor and the pad and then get stuck there.

    As for brake fluid on the pad, it is possible but it typically won't make the noise you described. It is possible that the new rear pads weren't bedded in properly; garages almost never tell an owner how to properly bed new pads. But that's unlikely on rear pads. And if that were the case the pads will usually squeal just on brake application. But from the noise you first described, I'd check the backing plates to see if they got bent - it's not at all unusual.

    By the way, the brake pads should always be in contact with the rotors. The o-ring that holds the piston in the brake caliper isn't round (in a cross-section view), it is square with sharp corners. It sits in the caliper at a slight angle so the piston can move easily toward the rotor but it takes more force to move the piston back, away, from the rotor. Thus the pads are always ever so slightly in contact with the rotor and no force is really being exerted to push the pad against the rotor. The pads just push harder against the rotor when you step on the brake pedal. As the rotor wears it may not wear evenly or there may be deposits that form on the surface at various points on the rotor. If this happens the 'high point' on the rotor will define where the brake pad will sit in relation to the rotor and every time that high point comes by the pad there may be a 'brushing' sound as the high point rubs the pad. It ususally isn't a 'squeal.' When this happens the high point will build itself higher and higher and then you'll feel vibration when you step on the brakes. Most people will incorrectly describe this as a 'warped' rotor. It doesn't sound like this is your problem.

    kearnsclan guest

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    Squeaky when cold

    Many thanks again to Louis !!

    My plan now is to inspect rotor and pads on RF.

    Of interest, have recently noted brake judder occationally, esp when braking sharply.

    To date regarding the squeak....
    1. I now think front bearing is NOT the culprit.
    2. Likely from the brakes, as little else would give such a squeak seemily related to wheel rotational speed.
    3. Sound seems louder on cold mornings. Atlanta has had recent cold snap and even snow...booo!!!
    4. Sound disappears when 'warmed up'. ie after 10-15 miles.
    5. Squeak not related clearly to turning or application of brakes.
    6. Questional new finding of occational brake judder when applying brakes.
    6. Possible brake pad contamination with brake fluid recently at flushing brake fluid event.

    Stay tuned for more info..... News as it happens !!!!

    thanks....

    kearnsclan guest

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    Squeaky when cold

    At last & with many thanks to all who thot with me on this problem.

    I think I have the culprit... the brake pads on RF. I think they were some how contaminated or something happened to cause the squeal when cold. After getting hot wiht braking, no noise rest of the day unless get totally cold again.

    Noise even varies now with brake pressure.

    I will need to change out the front pads later this year, so in the mean time it is easily to live with knowing I am not hurting the car.

    thanks.

    kearnsclan guest

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    Squeak is better with warm weather

    Just a note, the L front wheel squeak is much better in our warmer spring weather. It really makes me think a brake pad issue.

    Hoping to have relief soon with new pads.

    thanks to all.

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