Help needed with S320 W220 weird rattle - only at speed.

[shukerr]

Hi,

I've had a couple of garages look at a pretty annoying rattle with my S320 W220 year 2001 with no joy and a lighter wallet. Hopefully someone here can help!

I've recorded the rattle as I'm driving here:
Mercedes S320L W220 Rattle Noise on Acceleration - YouTube

It's pretty bizarre:

• Never occurs below 40mph no matter how hard you accelerate. Engine hot or cold.
• Seems to reduce once you've been on the motorway for a long time, but never goes away.
• Rattle stops as soon as you take foot off the gas.
• Seems to be proportional to how hard you push the gas pedal as opposed to the engine revs. i.e. if you are off the gas pedal on the motorway and then push the gas pedal the rattle starts straight away even before the revs have had chance to build.

One garage thought it might be one of the engine heat shields that is vibrating as air passes through the engine at speed, but attempts to secure the heat shield better haven't made a difference.


Other than that, the car seems to drive well. The only other problem is that the some of the internal air vents always blow hot even when air con is on, but I can't see how that would be related?


I'm very hopeful someone can shed some light on this! Thanks in advance...

 

[BlackC55]

What work have you had done to try and solve it? Engine mounts?

 

[BlackC55]

Can you feel it as well as hear it?

 

[shukerr]

Thanks for quick reply.
The engine mounts haven't been replaced. Neither of the garages expressed any concern with them. I guess this could be a potential cause!!

 

[shukerr]

It's definitely more of a noise than a vibration through the car, but I'm pretty sure you can feel it as well.

 

[BlackC55]

Can you replicate it on a lift with all the wheels off the ground and in D upto the speed it occurs at?

 

[shukerr]

I don't think that's been tried by either garage.

 

[BlackC55]

That is what I would do firstly.

 

[Benzowner]

Why did you get an Airmatic level Cancelled warning? It maybe the airmatic pump making the noise.

 

[ducatiboy]

Why did you get an Airmatic level Cancelled warning? It maybe the airmatic pump making the noise.

True

 

[shukerr]

Prop shaft coupler!

Thanks to Oliver and his team at Prestige Mercedes the rattle that has driven me mad for almost a year is resolved. I know this will read like a shamless plug, but this problem has been so frustrating and I'm genuinely relieved for it to be fixed at last.

The prop shaft coupler was in a really bad way. I can't believe this was missed by two garages including another supposed mercedes specialist and the car also passed an MOT like this. I'm told it should have been a clear MOT failure.

Very impressed with Prestige Mercedes and all repairs performed for a sensible price! Cheers Oliver.

 

[V12]

Wow! In that state I don't know how you didn't have some serious thumping during gear changes!

Great find and not too expensive.

 

[BlackC55]

Thanks to Oliver and his team at Prestige Mercedes the rattle that has driven me mad for almost a year is resolved. I know this will read like a shamless plug, but this problem has been so frustrating and I'm genuinely relieved for it to be fixed at last. The prop shaft coupler was in a really bad way. I can't believe this was missed by two garages including another supposed mercedes specialist and the car also passed an MOT like this. I'm told it should have been a clear MOT failure. Very impressed with Prestige Mercedes and all repairs performed for a sensible price! Cheers Oliver.

I'm really pleased that we managed to sort it for you!