On my way home from test driving a couple Mercedes', I was waiting at a light and my GS started making this high pitched wherring rather loud under the hood, so I turned I pulled into a parking lot and opened the hood with the car still running. I thought it was the AC comp but it didnt show any signs that . My belts are in good condition and they're not rubbing against anything and its the Alternator seems fine.

Everything was fine so I started driving again, the car then started making this low pitched brewing type sound and it started to idle a bit low when I stopped again . It made that sound all the way home and then as soon as I pull into my driveway, it suddenly stops. There was no type of hesitation or loss of power at any time. Also, I know I shouldn't have been putting this off but, for a while now every time I turn my AC on, something knocks briefly and goes away when I accelerate. Mind you, once the problem surfaced, I turned the AC off the rest of the way home

This is the first time this car has ever made a weird noise in the 12 years its been in our family. My car was probably getting back at me for going to Mercedes On a serious note, Does anyone have an idea on what it can be?

 

Cant help unless you post a video

 

I guess I'll have to catch it the next time it occurs but that means I'll have to carry my cam in the car. My friend thinks it can be one of the pumps.

 

You really pissed it off by test driving a benz.....I would go outside right now wash it and apologize for your actions

 

Lol she just got washed last week and shes still spotless.

 

The dealer did some magic. Jk. Gl. Sound like a pump. Gl. let us knw how it goes

 

The GS is showing you what you will go through every week if you own a Mercedes.

Just kidding. Ok, maybe not...

 

If it was a Mercedes you had for 12 years that would be a weekly occurrence.

 

I was going to say the same thing lol😜

 

Haha guys, I'm taking her to my friends shop one day next week and we're gonna listen to the pumps with a stethoscope and see what happens from there.

 

Just threaten the car that if it doesn't shape up it will be replaced with a Mercedes! It will get worse or better.....

 

LOL @ all the Benz comments! Sounds like the noise only occured while you were rolling. Do you feel vibration at all, like in the steering wheel. Is it possible you may have bad wheel bearings?

Ironically enough I've had to change bearings on my previous 99 C280 Mercedes and the issue your having kinda reminded me of it. I paid $60 bucks for all new wheel bearings and grease and replaced them myself in a little over an hour, Mercedes made it really easy.

 

I'm absolutely positive that its not the wheels. No vibration what so ever. I drove the car twice since that day and there were no noises oddly. I'm still going to take it do my bro's shop to listen to all the accessories and I'm gonna seafoam it.