I have a Mercedes Benz GL450. When I start the car in the morning it makes a squeaking noise. After driving the car for a few minutes the sound goes away.

  • Welcome to the site. You need to specify what the question is. – Zaid Apr 17 '15 at 21:15

It's probably a bad battery (low voltage), bad tensioner pulley (not allowing for proper grip on the alternator), or worn out serpentine belt. This is of course considering, one - it has a serpentine belt, and two - the noise you are talking about is a squeal on start-up (could also be a chirping noise).

When the engine first starts up, it requires a lot of juice from the battery. After it's started, the alternator starts replacing the juice which was used to get the battery back up to snuff. If the belt is slipping for the two reasons it will chirp/squeal. If the battery is getting bad, it could chirp/squeal because the alternator is working overtime.


Must be secondary air injection pump issue. I've had the same squeaky noise for some time and finally got a check engine light come up to indicate it's a secondary air pump. It's easy to replace it yourself, and costs about $100. I got mine here: https://www.amazon.com/gp/product/B00C7P4I0E

  • I am having the same set of symptoms. The noise I would describe is a squealing German Shepherd, with the tail tucked between its legs. The most embarrassing sound that could ever come out of a car, beat only by a simulated fart from its Airmatic suspension. Anyway, That was the sounds at 10F weather in Boston. Now it warmed up and the dog sound went away, but a code came on: P0410 air injection pump and/or hose. Thank you for the link!!! – Elijah Feb 11 '18 at 4:29
  • Also of note, more than likely the left and right valves would have to be replaced. They are $100 and $180. The pump comes in two flavors, MB original for $500 and Bosch for $120 – Elijah Feb 24 '18 at 4:10

it is most likely the serpentine belt being bad or could have some kind of fluid on it that is making the squealing. most likely the serpentine belt.

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