Ayanmitra

I recently completed a 300 miles journey and since then I am hearing this sound intermittently , which to be honest is scary to me. Can you anyone educate me on what is going on




Car :

s550 4matic, 2010.
140,000 miles.
Regularly driven, no major issues in the car.

Ultrakla$$ic

Sounds like the harmonics of a bad idler pulley or pulley in general. Raise the hood with the car running and see if you can isolate the noise even if you have to remove the drive belt for a moment to make sure its not a pulley. That's what I'd do anyways

vettebk

Definitely an idler pulley or tensioner. Not expensive. Don't ignore it.

Ayanmitra

So an update,
I figured out there has developed a crack in this pipe, which is plastic material and sometimes this thing knocks against the surroundings and makes this sound, see the video


now I know this happened after a long road trip ~ 500 miles.

But what I don't know is what would this part be called (presumably air filter snorkel hose ? )

and how much would it cost to get them replaced

is it normal for this part to damage ? any experience ?

thanks

Jaap

There's a partnumber on it.
Put it in Google and you'll find a price.

Ultrakla$$ic

To confirm that is indeed generating the noise, I would tape that crack up real good with duct tape and then try to reproduce the noise. Naturally you can replace that air intake tube but I find it hard to believe a "leak" in the INTAKE tube would produce harmonics like your first video but wth do I know

That part is an air intake tube.

After taping up the cracked tube, run the car with the hood open, turn the steering wheel left and right to see if that exacerbates the noise as well and come back with a video of the results please.

vettebk

Totally agree an intake hose crack is unlikely to make that sound but agree you should order the part and replace it. It will not be the last plastic part you replace.

Idler pulley and tensioner usually will make bearing noises on a cold start up. Typically after a warm up, the noise may subside or completely go away. Do not be fooled into thinking a warm dry bearing is any more reliable than a cold noisy bearing. Replacements are considered regular maintenance items. I would also check that serpentine belt because if it turns out it is a bad pulley or tensioner bearing, the belt will wear faster; and that is also a maintenance item.

I only buy OEM parts for my S600 but I have seen cheap Chinese parts for the S550 intake on the web. I doubt these parts are really good but they are certainly cheaper. I am sure FCP has what you need and they cover the parts for life. They even told me coil packs for the S600, a known trouble area, are covered for life. I could not believe it, but FCP confirmed it.

Keep us posted on both the intake and the serpentine issues. Good luck.

EasyPhil

Check the AC pulley that's what this sounds like and will fail soon.