becool23

Hello Everyone,

Just picked up a 07 clk550 with 20k miles. On cold starts I would hear a squeeking noise coming from the engine compartment but it would go away after the about 3 to 4 minutes. Please let me know if this normal (as this is my first benz) or should I be concerned? Car Idles smooth and drives like a dream otherwise. And also the clk starts up without any problems or delayed cranks.

Your input will be appreciated.

Rudeney

It's probably the secondary air injection pump. It forces fresh air into the exhaust when the engine is cold to reduce emissions. Mine does this, too. It might be a symptom of eventual failure of the pump, but I wouldn't do anything about it until it actually fails and triggers the MIL.

becool23

How many miles are on your car? How long has it been since you have been experiencing this problem in both time and miles? And how long does it take for your engine to stop squeeking after the cold start?
I ask all this because I just got the car 2 days ago.

Thanks

Rudeney

I have just shy of 50K miles. It's done it for at least the last 10K, more than a year. It does take a few minutes before it stops (i.e. when the exhaust temp is warm enough that the ECU decides it no longer needs the fresh air injection). The air pump is easy to find - its a big motor looking think right on top of the engine, under the front engine cover. It has a hose coming out of the rear engine cover connecting to it.

becool23

with the vehicle standing at the dealer lot for a few weeks outdoor in the cold, is that a contributing factor for the squeeking noise at cold starts? Because it also seems to me that the squeeking noise has been quieter but now the car is also garaged....?

Rudeney

Maybe. Mine stays in the garage, and it doesn't get terribly cold here, but mine still makes noises occasionally.

becool23

One last thing. When you put your car into drive or reverse, does your vehicle move pretty easy without giving throttle like when pulling in or out of the garage. I have a Lexus rx330 that moves and even picks up speed with out me giving any throttle. Again my car has only 20k miles. On the side note, there is no hesitation when I apply the throttle and the vehicle drives smoothly.

Rudeney

No, mine actually requires a little throttle to start rolling, especially in reverse. It's better with the transmission in "S" mode as "C" uses a higher gear (and yes, the 7GTRONIC has two reverse gears).

becool23

Thanks Rodney.
So seems like my car is behaving normally