Humming noise

[vanzant]

Just had my power steering pump replaced (it was leaking badly) on my 98 Q45. I was hoping that that was the source of a humming noise coming from engine area. The noise intensifies when accelerating. Any thoughts? Water pump?

[maxnix]

When were the accessory belts last replaced and the pulley bearings inspected?

[vanzant]

only the PS pump belt was replaced. Pulley bearings have not been inspected. Could the noise be coming from a leaky vacuum hose?

[maxnix]

Vacuum hoses usually don't hum, they whistle.

[vanzant]

It's a medium high pitch. When I acellerate or press on the gas it gets higher. Even when not moving. It makes the same noise in all gears, including park and rev.

[maxnix]

My bet is on a pulley bearing. Check your belts. When you replace the cracked ones, any bearing defect at all requires replacement as any noise or lack of smothness is greatly amplified under operational stress.

You will then realize why when one goes belt bad, all are replaced along with defective pulleys to save on repeat labor or time.

[vanzant]

Thanks. Question: Do the belts rotate faster as the RPMs increase?

[qship96]

Absolutely !!!!

[Infinitiguy19]

I was expecting a different answer I am Surprised you were so nice.

[vanzant]

I should have taken a half-second to think about that question before I posted it. Slightly red-faced.

[Jeff Williams]

Check your fan clutch assembly. It makes a buzzing noise when the bearing siezes up and causes the fan to spin the engine RPM.

[Q45tech]

Also alternator and compressor bearings. Measure the pulley diameter vs crankshafy pulley diameters to calculate RPM multiplier.One normally uses their stethoscope to pinpoint the offender.