2003 530I Squeak at low temperatures

[ohlongjohnson]

Winter came and car started making this weird noise, here is the video:
https://youtu.be/-cXT7-YTy-U
this sound comes when temperature is below 32F (0C) as lower temperature goes as more often it squeaking, I don't have any check engine lights or fault codes on dashboard. Looking through the forum thought it might be SAP itself but it doesn't make jet noise only this squeak while car is moving, people saying that secondary air pump runs only few seconds when car is first turned on and weather is cold, it might be check valve? Also it can't be heater fan because this sound appears when it turned off. Sound doesn't go away when car is warm... If someone has this or similar problem please share with your thoughts. Thanks in advance!

[1823alex]

SAP runs until the temp gauge reads just above the blue part of the temperature gauge I believe, then it should automatically shut off. If there was a check valve issue, the car would probably throw an SES light and a P code for emission air pump.

From the video I can't really hear it well or pin point it myself so hopefully others can chime in, but is it possibly any of the pulleys or maybe the serpentine belt? Also possible for it to be the power steering pump, wouldn't hurt to bleed it by raising the front end of the car and then do a few steering rotations lock to lock.

[Twistytee]

Sounds like a bad idler pulley to me.

[ohlongjohnson]

SAP runs until the temp gauge reads just above the blue part of the temperature gauge I believe, then it should automatically shut off. If there was a check valve issue, the car would probably throw an SES light and a P code for emission air pump.

From the video I can't really hear it well or pin point it myself so hopefully others can chime in, but is it possibly any of the pulleys or maybe the serpentine belt? Also possible for it to be the power steering pump, wouldn't hurt to bleed it by raising the front end of the car and then do a few steering rotations lock to lock.

Sounds like a bad idler pulley to me.

Thanks for response! The most clearly you can hear it from 4th to 6th seconds of the video and 12th to 17th. Serpentine belt was replaced together with pulleys like 13-15k miles ago, don't think it is the problem, power steering liquid was replaced like 20k ago with few hoses and reservoir. Will check power steering pump tomorrow morning, the most strange for me is that this noise occur only at very low temperatures.

[DennisG01]

Serpentine belt was replaced together with pulleys like 13-15k miles ago, don't think it is the problem, power steering liquid was replaced like 20k ago with few hoses and reservoir.

Don't assume. Take the belts off - if the sound goes away, you're narrowed the culprits down considerably. If the sound doesn't go away, you've eliminated a variable.

It's very hard to hear, but it almost sounds like a whistling noise to me?

Does it go away after the engine has been running for about 30 minutes? Everything on the engine should be good and warm by then.

Does it change pitch/sound with RPM's?

[ohlongjohnson]

Don't assume. Take the belts off - if the sound goes away, you're narrowed the culprits down considerably. If the sound doesn't go away, you've eliminated a variable.

It's very hard to hear, but it almost sounds like a whistling noise to me?

Does it go away after the engine has been running for about 30 minutes? Everything on the engine should be good and warm by then.

Does it change pitch/sound with RPM's?

Thank you for response. Unfortunately can't remove belts because it squeaks when car runs, it some kind of whistling yeah. Actually it doesn't matter how long engine runs, once we drove from upstate for like 3 hours and noise was still present, it doesn't change pitch, sounds the same all the time, might disappear if you press gas, when pressing gas you like causing abrupt to this short term whistle. Today checked power steering pump, it moaning a little, as louder as i turned it to lock position and doesn't matter left or right, but not too loud, I might hear it a little when sitting inside the car, whistle might be pump?

[DennisG01]

You misunderstood. Remove then belts AND run the engine (short time, of course).

Power steering pump... it's normal for it to get louder when you turn it fully one way or the other. That's normal for all pumps/cars. It's the relief valve operating and doing it's job.