w124 220 coupe fading whistle sound

[ladd220]

Hi folks,

I'm new to this forum and was hoping someone could help and perhaps also benefit from my query.

I bought a 1996 w124 coupe e220 a year ago. 85000 miles. Great car. However, over the last 2 months, it has developed a whistling sound. At first I thought this was coming from the heater fan, as it sounded like it needed oiling. But it continued even when it was off. However, its now become more frequent and more concerning.

It happens when i have selected a gear and the brake is pressed. The whistling sound comes and slowly fades out. Whilst driving its ok, but if I stop at lights, it can return. It happens even when the car is warm. The gears also jerk if I select D to R very quickly and vice versa.

I tried to check the atf level but there is no high or low on the atf dipstick. Only temperature scales on both sides. I checked it with engine running after a drive and whilst in P but can't understand it. The fluid level was near 30 degrees c, and was fairly clean. No odours...

The whistling sound sounds like a fly wheel but not sure what it is...

Sorry for the long post, but wanted to be thorough... all help appreciated...

Thanks.

Laddie,
1996 E220 coupe W124

 

[kth286]

it could be a loose vacuum pipe leaking, exacerbated by the use of braking vacuum.

see under dash in engine compartment where there is a vacuum connection block with several pipes into/out of it.

make sure they are all secure and not become a loose fit.

 

[ladd220]

Thanks for the quick reply. I'll check this afternoon and post my findings...

Cheers.

 

[grober]

If your auto gear change is affected then its possibly a vacuum leak as has been said. Check the vacuum actuator and pipework on the side of the gearbox- in particular any short flexible rubber push fit joint pipes - they can go hard and split-sometimes difficult to spot. Your ears will be your best guide- try to get the car up on a lift somewhere as its much easier to see this area from below.

 

[ladd220]

Fellas,

things seem to have become a little more complicated..... over the last 3 days i've tried to replicate the noise but without any joy. so, its been difficult to try and hear where the noise is coming from. but, i went out to tesco's last night and it happened again...

I've not made any changes whatsoever, so i'm beginning to think that there may be a connection with the ambient temperature.... During the day it was more warm and there was no noise... and then at night, temperature was low, and the noise returns...

I checked all the visable vacuum pipes from in the engine compartment and they seem to be ok...

Weather permitting, i'm going to get under the car tomorrow, but what do you think about the ambient temperature influencing the noise...?

 

[grober]

Unless a rubber junction pipe is harder when cold and leaks? There is also a small fan in the centre light console that samples cabin air for the heater/aircon controls -its not that is it?

 

[ladd220]

sorry for the delay in getting back to you all....

with the warmer weather the noise hass not been apparent. However, the other day it was raining and the bottom of the car had been splashed. The noise came back... excpet only this time it was like a punctured bicycle innertube in water...!!!
Its definately a vacuum leak. but not sure which pipe/rubber it may be...

There's one pipe that goes into the gearbox on the passenger side - its white and goes into what i think is the vacuum modulator... i tried to take it off but couldn't as it seems to be clipped in somehow. i didn't want to break it so if anyone know how it comes off, please let me know, it'll save me loads of time...

There are also a few vacuum pipes that go intop the drivers side of the gearbox, theyre green and red. but i dont believe thay are the problematic pipes do to the sound.

so, if anyone can suggest hoe to remove the pipe going to the Vac modulator, that would be great.

BTW, in the meantime, i've changed the power steering fluid and the steering damper on my car, as the damper was damaged (the fluid from inside it had leaked) and the PS fluid was filthy....... the result has been very pleasing...much more smoother and absorbs the potholes much better...!!!

Once this whistling is solved, i'll be changing the transmission fluid, brake discs, brake fluid, and diff oil... will keep you guys posted on how it goes and the result i experience.