MBc300elvis

2008 c300 it's killing me when I press on the gas low rpm it makes this wirling sound idk if I can hear it from the outside but it's not the steering positive,thought it would go away nothing yet owned it for 6 months now

Don't know what to do someone help what could it be??

w204_Generic

That could be the air intake you are hearing. Low speed so there is no wind and you hear it more.

Glyn M Ruck

It could be the transmission oil pump. Can you hear it stationary in neutral or park? It could also be the poly V belt tensioner or idlers.

MBc300elvis

Not that already replaced it good idea though

MBc300elvis

When I rev it it gets wirly on drive neutral and park. thanks for the idea I've got an appointment for a software issue gonna take it to mercedez see what they think.

JohnnyC300

Similarly, I noticed that when using the suggested gear ranges of D1 and D2 the engine exhaust note sounded much more high pitched and whiny as opposed to its usually deep robust sound. Is this potentially also the transmission oil pump/poly V belt/tensioner/idlers?

Glyn M Ruck

It sounds as though it could be the transmission oil pump you are hearing. It is a little variable unit to unit & is normal. Benz redesigned & changed to an aluminium pump to reduce noise but it's still there.

MBc300elvis

Yea I'll probaly have to deal with it till I trade in next year ... Do you guys have it in your cars at all? Or ever hear it in a friends car or somthing?

Rodpwnz

I hear it in lower gears, 1 and 2. Whenever I drive through my university parking structure it is very noticeable. Like Glyn said, I assume it is normal. I feel like manual transmission and more sport oriented cars such as BMW don't have the same noise whine.

MBc300elvis

Yea it gets to me a lot. gotta blast the radio to ignore it lol

gmphertford

If diesel possible turbo noise, transmission will not make noise if in park.

Glyn M Ruck

The transmission pump does make a noise in Park. It runs continuously at input shaft speed with engine running.

MBc300elvis

Not diesel and transmission pump sounds like it mostly

Glyn M Ruck

On some older 722.9 transmissions the pump actually makes the most noise on start up in Park. You get a bit of a roar out of the pump until pressure normalises in the transmission & then it quietens down.

MBc300elvis

Yea exactly I hate that certain noise though sucks

Glyn M Ruck

Even the old 722.6 5 speed did it. It's just a Benz noise you get used to. If it gets really loud it can be sign of a failing torque converter but I mean really loud.

MBc300elvis

It's really not that loud just annoying honestly lol

Glyn M Ruck

The TC makes a deafening howl when the bearings fail.

MBc300elvis

Nah that's deff not it

95_993

I have noticed a slight hum of the pump at low speeds when there is not much road noise. Immediately knew it was transmission as it has a very distinct sound.

Glad to hear from Glyn that this hum is likely normal is a known characteristic of this transmission. I am still getting acclimated to the feel and sounds of this car as I have only had it a couple weeks.

MBc300elvis

Yea I'm trying to get used to it. Blast the radio it helps lol

Glyn M Ruck

This has been a characteristic of Benz cars for a long time.

722.9 oil pump

julianmousa

Got the same problem, anything new -what can it be?

MBc300elvis

Nah bro it's killing me I had a loaner two days ago same car just 2014 so quiet I was jelous brother in law is a mechanic said just how 2008"s are

nycrx7

Sorry to rehash an old topic...

but does the whining sound... is that like an electric motor from a R/C car? I picked up 2012 C250, and when I am starting off, I can definitely hear that sound. Was curious if this was the sound everyone else heard.

Thank you