Eich

When I first start my car, I hear a loud groan / noise for about 4-5 seconds and then it fades away. Any idea what this is and if it is normal?

About a year ago, I had an '04 CLK500 and never noticed such a noice at start-up.

Benz-O-Rama

SBC pump. Totally normal.

Try this:

1. Start car
2. Pump brake pedal 5 times
3. Hold brake pedal down on 5th pump


You'll hear the SBC pump engage. If that's the same sound you're hearing it's completely normal. It's the SBC pump priming the brake system. This is a TSB out to reduce this noise if it's annoying to you.

Eich

Thanks for the very quick reply !

This sure is a noisy car at times! It was warm the other day. I started the car and the AC came on Max Cool. Between this initial SBC Groan and the cooling fans winding up to full speed, my car sounded like a jet was about to take off. It's a little embarassing in a parking lot with people around looking at your car like it's about to explode !

Benz-O-Rama

I know what you mean. I will sometimes manually select one fan speed lower when my MAX/AC light come on. People look at you like your car is ready to shoot off into orbit.

mcleantmw

The AirMatic pump can be noisy too......especially after driving in hot weather. It will start making a slight thumping noise from the left front driver's side of the vehicle. Mine was replaced this month at my MB Dealer and even the new one I can hear after driving for a while but much better than the old one.

gaazmon

Lol, it does sound like a jet. Yesterday I was leaving palm desert and it was 109 degrees out. So when I started the car, I had put the fan on all the way and when we were getting into the car, the thing just was soooooo loud. My brother was like wtf, is that normal? It kind of sounded cool though,

K-A

These cars do have LOUD A/C units. Kind of odd really, a car like this IMO should be a bit quieter in that regard.

Eich

It's not really the AC unit that is loud. It's the fact that the cooling fans (attached to the radiator) go into hyper-speed when the AC is on the "Max Cool" setting.

I don't think the cooling fans should go into full high speed unless the engine's temperature is above a certain threshold. The other morning I started my car when it was only 70 degrees F outside. But the AC went on Max Cool because it was like 80 degrees inside the car and even though the engine was very cool, the cooling fans hit warp speed and sounded like something was about to exit dramatically through the hood.

CLEK500

my wife asked me " did you modify your cars again???, how come it so loud, my co-worker ask me if the car have problem", and I were like " nooo" lol

vettdvr

Loud Yes. sound like a jet,, nope

When your legs are quivering holding the brakes with both feet, and you are at mil power, then move the throttles to MAX afterburner and release the brakes,, Nope not, No Mercedes sounds or feels like Full Afterburner take off and 90 seconds after takeoff cruise at 30,000' and .9 Mach. The jet is really smooooth cruising. But night flying at 45,000' solo in a Mach 1 fighter sorta makes you feel really small and alone.

But my E500 is also really noisy with loud fans. Louder than any car if have owned, however inside the noise level during start up is acceptable.

lkchris

If you're still under warranty, you can have for free a DTB procedure that installs a different hose to the SBC pump that's supposed to quiet things a bit. It's a subtle improvement IMHO.

If you're not under warranty, you can pay for it.

DTB = P-B-42.46/27e