CLTw204

Hi - first post. I own a 70k mile 2010 C250 (Canadian market). I hope this post is as helpful to future users as it may be to me.

Issue: whining noise that fluctuates up and down with vehicle speed (not RPM).

• The whining noise (almost white noise like) will be audible after vehicle is going 20+mph.
• It is parallel to the vehicle speed, not the RPM. That is, the sound does not decrease when RPM drops in higher gear as speed increases.
• I was thinking it is power steering pump related, as the steering rack has made groaning AND whining noises at full lock, or close to full lock
  • The p/s fluid is correct (not low or high)
  • I did purge the system of air
  • No leaks to speak of
  • When car is in park and I rev RPM's to 3-4k, and turn the steering wheel to full lock, a "buzzsaw" noise can be heard. Not crazy loud, but audible for sure
  • There is no loss in power assist to steering when turning steering wheel

Is it power steering related based on these bullets?

TimC300

With the car running what does it sound like under the hood with your ear down listening to the pulleys? When im on the highway with the window down in the left lane with concrete barriers right next to the car i hear a sound that drives me nuts, hard to describe but sounds belt/pulley related.

If its with the vehicle speed then its wheel/bearing related, if its rpm then its probably pulley/belt related, im assuming.

CLTw204

With ear up close to pulleys - I can hear a soft (very soft) whine but cannot place it. I thought the wheel/bearing AND pulley/belts ALL rotate same speed? And when driving with door open (don't ask ha), I can hear the "white noise" I mentioned above coming from bottom of car.

JettaRed

iTrader: (1)

Not sure where my reply went (internet service upgrade today), so I will summarize...

• Speed-related noise could be wheel bearings and/or CV joint.
• RPM related noise is probably steering pump (which is driven by the crank pulley/engine speed).

Wheel bearings and pulleys DO NOT rotate at the same speed. You will hear steering pump noise at full lock of the steering wheel in either direction.

Lastly, check to ensure there's not a rock or something stuck between the disk shield and the disk. I have had that happen on a car I once owned.

JettaRed

iTrader: (1)

Short drive?

JettaRed

iTrader: (1)

Another thought is that you could have a stuck brake caliper and the pads are rubbing. Maybe the parking brake has not fully released.

Is this noise new? When did it first show up?

TimC300

hard to describe the sound, its the sound the belt makes when you start the car in the morning and goes away after a minute or two, but not a squeeking sound. Could be one of the idler pulleys I didnt replace, or the power steering pulley isnt exaclty quiet when listening under the hood. Only time I notice it is driving through Boston where they have the moveable concrete barriers for the travel lane, those barriers are set right on the line so your 12" from them.

TimC300

Was going to say jack up the front end and spin the wheels, listen for a noise.

JettaRed

iTrader: (1)

That was a joke. You know, “drive me nuts” “short drive”. Get it?

It’s not funny if I have to explain it.

CLTw204

Sorry - you said wheel bearings as in those on axle. I misread. And FYI: Noise does NOT go up and down with the RPM - which tells me then that it has NOTHING to do with the crankshaft, serp belt or belt accessories, YES? If it turns out to be a rock on the brake shied, the amount of concern I have had over past few weeks will be laughable. But the relief would be welcome -thanks for opening my mind on this one.

Noise is new, showed up 2 weeks ago. I need to get a look at brakes but they are due for replacement

Ok will do this and place car (AWD) in neutral to be able to spin fronts - hopefully it is indeed the caliper! Would make sense given the data (appeared out of nowhere, power steering pump function is normal, and brake pads likely near dead)

JettaRed

iTrader: (1)

If your pads are that bad, it may very well be the pads. Some use a bent piece of metal to rub agains the rotor just before the pad material is completely gone. Being as old as yours is, I would think the pads have been changed at least once. There is a good chance you are hearing the wear indicator.

A good source for pads and rotors is www.rockauto.com or www.fcpeuro.com. FCP Euro is more expensive than RockAuto, but you will only pay once for whatever you get there. Their lifetime replacement guarantee means you buy once and then future purchases are reimbursed.

CLTw204

The pads are Centric® 500.13400 - Posi Quiet Pro™ Semi-Metallic Front Disc Brake Pads. And I was aware of the FCP lifetime replacement which for sure- can be a good move.

CLTw204

Update - brake pads are quite healthy and full. I also notice the noise is there even when coasting at 15+ mph with engine off (in neutral).

On another note - earlier, I had a buddy turning the steering wheel lock to lock 12-15x without jacking up the front of the car. Are the w204 steering pumps known to burn out? I noticed some smoke (steam) coming from the power steering reservoir when I had cap off checking for air bubbles..

CLTw204

I would add that with front axle off ground, neither front wheel shows damaged wheel bearing related noise. I do hear some brake pad rubbing against disc, with 15% of the meeting surface causing slightly more amplified noise on right front.

JettaRed

iTrader: (1)

Sounds like either stuck caliper pistons or un-lubricated pad pins or tracks. In this case, the pads continue to be held against the rotor, causing the noise. Normally, they should pull back slightly off the rotor when the brakes are not applied.

Remove the right front wheel and pads. Compress the pistons back into the calipers (remove the brake fluid cap first and put a rag around the reservoir in case any brake fluid overflows). Apply brake grease to the tracks the pads ride on. (I'm sure there are some YouTube videos on changing brake pads.)

When applying your brakes, do you feel any pulsing in the brake pedal?

CLTw204

I do not feel pulsing. Thanks - sounds like i need to dig into the brakes asap.

JettaRed

iTrader: (1)

This is for a newer C300, but many of the steps are the same. Not sure if you need (or can) move the pistons to the fitting position. I've never done that with mine (the 2004 SL500 was completely different with its braking system).

JettaRed

iTrader: (1)

Another good one, just not sure what year this car is.

CLTw204

Got it. Thanks! Any idea on lifespan of the steering pumps in these cars? Are they robust? I don’t see much forum content related to problems
or failure.

JettaRed

iTrader: (1)

This is the best to watch!

TimC300

Just an fyi with both front tires off the ground you can spin each wheel even if its in park. They just spin opposite directions. No need to put it in neutral. Probably bad if you put it in neutral if the rears are on the ground preventing it from rolling. Obviously the e-brake would be set.

I have a constant rubbing noise on my front passenger side, with the wheel off i was spinning the rotor and I noticed the air gap between the inside pad and the rotor wasnt consistent, it would contact and then 180 degrees there was a small gap. Took me awhile to see it, looking different angles, sticking a flashlight under there. Im hopeing its the rotor. been like this for a year or two. I dont notice anything else besides the slight scraping noise, its louder after washing the car then goes away, im thinking its the rust buildup from the water. I dont see the need to fix it.

CLTw204

I did notice the wheels rotate counterclockwise sans neutral. Thanks!

CLTw204

I did hear some brake squeal when reversing from a stop.

Any word on if the w204 steering pumps reliable?

TimC300

Going back to your 1st post and the sound occurring going over 20mph. Have you had someone drive your car past you going over 20mph as you're standing on the side of the road? Once i was trying to figure out where a noise was coming from so I had a neighbor get in and drive around while I was outside the car listening. Wheel bearings you may not notice anything wrong just spinning by hand, but once they get heated up driving on the highway they start whining.

JettaRed

iTrader: (1)

I’ve not heard anything about the PS pumps. I think they’re good.