killatee18

Hi All, I live in NJ where it is starting to get really cold out in the morning...when I go outside to start my car in the cold, Im starting to hear a pretty loud whistling/chirping noise under the hood. Any idea of what this might be??? I have no clue what it is...I havn't opened the hood while the car is started. After the car warms up a bit the noise gets lower and lower and then eventually goes away. I will take it to the dealer as soon as i get a chance as it is still under warranty but it will be hard to replicate the sound at the dealership since my car will already be warmed up at that point. Has anyone else ever experienced this problem?? Any help would be greatly appreciated. Thanks!

Barry45RPM

In my experience in the past it is either a belt a pulley or a tensioner.

bobsquad7

I would suggest buying a can of belt dressing ($3 or $4) & spray the belt before spending $$ at the dealer. Most any auto parts store will have some. For best results spray it with the engine running at idle, just be careful - don't get a finger or other body parts tangled up in the belt.

99210

on engine 272 it is either upper idler pully, mb had recall, or belt tensioner, if under warranty mb will replace///

Firestopper0383

When you go to the dealer, explain to him it is a cold start noise. He may want to keep your car overnight to enable a cold start the next morning. Depending on the dealer, they should provide a loaner car if they need to keep your car overnight. But, from what you are saying, it does sound like a tensioner may have seized up a bit causing a belt noise(chirping) before the engine warms up.

sunnySD

Awesome! Thanks for the responses guys. I've had the same noise in the morning 3 times and figured the dealer would never just "know" what the problem is. I'll now say people have said it's a belt.

vettdvr

If you run the pulley to failure the plastic will fracture due to heat, and you will throw the belt.

My $$ is on the small top belt tensioner idle pulley. I changed mine at 70,000 miles. Typical failure, small pulley = fast turning loaded bearing = early failure.

IMO this is a design failure due to the small diameter pulley. For longer life a larger diameter pulley to reduce rpm's and this will put the bearing in a better service factor rating.

The belt is easy removal and the pulley is about $20. I used my lathe to open up the pulley I removed and pressed out the bearing. It clearly said made in china on the bearing. I found a replacement bearing for $4.00. So since I bought the car new I must draw the conclusion that the German made MB priced over $65,000 new has in it $4.00 China bearings. The OEM part in the box will have the same China bearing would be my guess.

Another quality OEM part!