isosunrise91

My 2009 e350 has had this very annoying chirping sound since I purchased it in early November. I was told by the previous owner that "some pulleys and belt were replaced", which was verifiable by the shop she had the work done at. Im not sure of exactly what was done as my notes on the car are at my desk which I am away from at the moment. I have attached a short video of the car today. Cold whether or not the car makes the same noise. What could this be?

bernard farquar

You need to open the hood.

Then use either a hose, or a purpose built stethoscope to determine the source.

kjb55

My vote is the upper idler pulley.

isosunrise91

loudbmw

I replace two idler pulleys and serpentine belt on my '09 E350 with 90,000 miles. The pulley and spring on the tensioner seemed OK so I left it as is. Started her up and the new belt squeaked like crazy as it went around the tensioner.

Belt alignment was perfect. Did some searching and pretty much everyone said to replace the tensioner. The Gates branded one from Amazon was an exact match for the one on the car (it was a Gates that was factory installed).

Success - squeak disappeared.

ps2cho

The aux idler above the alternator wears the quickest out of all. Commonly can seize and break, I ALWAYS replace that one every 80k miles. Turn the tensioner pop the belt off and spin that idler, you'll likely hear its bad. Do it before it breaks off and leaves you stranded.

cetialpha5

FCPeuro has the parts and they come with a lifetime warranty. Otherwise I'd get the parts from rockauto which has the continental kit with both pulleys, tensioner and belt for around $120. I'd do it all at the same time as they all have a history of failing at some point. You could even throw in a new thermostat while you're at it as those are also known to fail and you have to take the pulley off anyway to replace the thermostat.

isosunrise91

I believe the idler pulley was already replaced. Im pulling records today and will see. I remember the previous owner telling me the chirping noise happened after they did a repair.

isosunrise91

Here is what I know.

10/2018-Water Pump, Serp Belt, Driver Belt, Pulleys - replaced as car broke down while driving. - INDY SHOP

10/2017- Battery Replaced with Bosch Battery- INDY SHOP

4/2017- 130k Service, All Pads Replaces, Coolant Leak found, sealed. -MB DEALER

12/2016- 120k Service, Wiper replaced, idler Pulley + Belt replaced- MB DEALER


Hmm.. Why the noise if these pulleys seems to have all been replaced. I noticed one of the pulleys is silver and rusty looking.. doesn't look new to me?

loudbmw

Does the rusty pulley look like this?


If so - they didn't replace the tensioner/pulley assembly and is likely the cause of your chirp.

Lou

isosunrise91

Here's a video. Sorry it's upside down I'm not sure what happened. No noise as cars warmed up and it's typical for the noise to stop. If you notice one pulley is silver and rusty looking although at the same time it looks the Newest if that make sense.

rustybear3

At this point it could be anything....from pulley wheels (my guess) to a bearing in the water pump. Save yourself the aggravation and take it to an Indy shop or MB dealer and get it diagnosed.

isosunrise91

Update: had a mb tech look at the car and he immediately pointed out the tension is shaking back and forth, not normal. Suggests replacement. Belt is also slowly shredding. I found a nice pdf on here that makes the job look easy. Few questions.

Where can I get tools needed?

Can I use a tensioner from amazon or auto zone? Same question for belt..