raverx3m

2011 c300 4matic
when i accelerate there is a whining sound only audible at higher rpm in every gear sounds the same.
closest thing i can relate it to would be a dremel tool spinning up
visually there are no signs of anything broken.nothing else makes any suspicious noise at idle or lower rpm.its a bit hard to troubleshoot when it only happens when i accelerate

just wanted some ideas on what it could be so i can check those parts if there is a common issue that does it in these cars

Demvang

My initial guess … belt, tensioner, pulleys

raverx3m

what else can it be?

can torque converter or transmission make this high pitch whiny noise?

CaliBenzDriver

What's your current mileage??

Consider changing the gear oil in both rear and front differentials.

Whining is exactly what these do with bad input bearings.

Fresh oil may not entirely stop the noise but the damage yes. If it's not in severe stage, don't worry as something else will materialize.


Other maintenance that need timely service:

• Coolant mix
• Brake fluid
• Tranny ATF
• ....

Some of these service items are quick. Be sure to use specific MB fluids... not simply "compatibles" that will magically destroy tranny, radiator and water pump.

raverx3m

transmission fluid has been changed.diff usually makes a different sound
this is something small. or something spinning fast. its a higher pitch sound than diff usually makes
i had plenty of experience with hondas and diff hum/whine lol

TimC300

May not be the same issue as yours but I was hearing a noise that I though may be a worn idler pulley or maybe the power steering pulley/pump. I recently replaced the power steering fluid and the noise seems to have gone away. I would hear the noise when I was driving close to a concrete wall or barrier and my window was down, the sound was probably bouncing off so I could hear it more.

RobertR728

I'm wondering if your crankcase vacuum system has a issue. It will cause a squeal when the engine gets hot. Try and remove there engine oil cap and see if there is a excess of vacuum there. If so that PCV diaphram could be the problem and it will go away with the oil cap off. If it does go away you will need a new diaphram.

raverx3m

can torque converter make a whining sound?
in park it does also starting at around 3000rpm
during acceleration also
im also experiencing the same issue that many people in amg forum described where cold transmission woulfd lag going into second gear but goes away when warmed up.

also there is a hissing wound like when you rub 2 sheets of paper together.

im juat trying to troubleshoot without replacing parts because if transmission and tq is bad then car is basically garbage because that will cost more than the car is worth to replace

raverx3m

can torque converter make a whining sound?
in park it does also starting at around 3000rpm
during acceleration also
im also experiencing the same issue that many people in amg forum described where cold transmission woulfd lag going into second gear but goes away when warmed up.

also there is a hissing wound like when you rub 2 sheets of paper together.

im juat trying to troubleshoot without replacing parts because if transmission and tq is bad then car is basically garbage because that will cost more than the car is worth to replace

raverx3m

should i just pretend i have a supercharger and keep driving?
isnt there a common issue with a bearing somewhere in driveline in these cars?

CaliBenzDriver

intermediate bearing does not whine but vibrates the prop shaft.
You can start throwing these maintenance parts after testing for freeplay.

TimC300

Funny you mention a hissing sound like rubbing two sheets of paper together. That is exactly how I would say it sounded previously before replacing my power steering fluid.

I would notice the sound driving on the highway in the far left lane when driving right next to concrete barriers and in the tunnel. It would get louder with the rpm, when stopped due to traffic i would hardly notice it then step on the gas and its there again. I thought it was an idler pully I didnt replace or the power steering pump itself. I swapped out the power steering fluid and have yet to hear the sound back. I didnt even realize it until driving on the highway the sound was gone.

Not saying its your power steering pump or the fluid. Just thinking that is how i would describe the sound I was hearing.

raverx3m

im gonna check that out thanks

TimC300

I made a thread when I replaced the power steering fluid and even commented how the noise I was hearing went away after doing it. https://mbworld.org/forums/c-class-w...-question.html

I will add the power steering fluid level was not low, in fact it was all the way up to the full line when hot, even though the fluid was cold. I corrected it to the proper level.