03 530i Power Steering Pump Noise

[Twistytee]

My car has developed a strange whistling/whirring noise at start-up. Does this sound like I have a cavitation problem with the power steering pump? It's definitely isolated to the front driver's side of the engine bay. Doesn't sound like a typical bearing or pulley issue. I've cleaned-out the PS reservoir and flushed the system with new ATF. Seems to go away a few minutes after start-up but then comes back whenever I restart the car.

https://youtu.be/IWtKmJ8P2yk

[edjack]

Remove the PS belt, and start the engine from cold. Does the noise persist?

If not, carefully examine the idler pulleys.

[Twistytee]

I’m hoping to have more time to troubleshoot this weekend. I replaced the water pump and power steering pulleys when I refreshed the cooling system. And the tensioners appear to have been replaced when the PO put in a new alternator. I suppose it could be a bad idler pulley but I’ve never heard a sound with that type of resonance coming from a bad idler bearing.

[DennisG01]

Can't hear the video where I am.

In addition to what Ed said...

You didn't mention how old the tensioner (that PO replaced) is, but anything can go bad.

Use a Mechanic's stethoscope or a long handled screwdriver or even a dowel to pinpoint where the noise is coming from. Can also try squirting some water on the various pulleys to see if it temporarily stops the noise.

[DennisG01]

Could hear the video, now. I'm sure it can be any number of things, but it sure sounds like a pulley bearing to me.

[jagerhund]

DennisG01 is correct.... use a stethoscope or simply a long screw driver.... I have large screwdriver I use for this purpose.

Sounds somewhat similar to my secondary air pump when it died.

Good luck and let us know what you find.

[geargrinder]

The PS pump does make buzzywhizzy noises when it starts to crap out.

I was going to push the "flush repeatedly with new quality ATF" but seems like you tried that. Might be time for a pump.

[Twistytee]

Circling back with the resolution. It was the idler pulley bearing. Isolated it using the large screw driver as a stethoscope. It could barely turn when I took it off the car. I went ahead and replaced the primary accessory belt tensioner and the a/c tensioner when I had the fan shroud off. Hopefully no new noises for awhile. Thanks all for the tips/advice.