speed doc

Hi Guys, new to the forum. I just picked up my new 2008 sl55 today from the dealer and the car is simply awesome. My question is I hear a constant hissing sound from behind the seats. Its just loud enough to be annoying. Any thoughts or wisdom on what this is. Thanks in advance guys.

Cyrusx7

A snake?

Haha, jk.. Seriously though, my best guess would be its something with ur stereo. There are two small speakers in the bar under the rollbar. Listen carefully and see if its coming from there. Adjust the volume up and down to see if it makes a difference, maybe its some sort of interference.

speed doc

I thought about that but I don't think its the radio. Its still there when the radio is off. I'l call the dealer today. I'll keep things posted. Thanks for the input.

theboogers

ventilated seats have fans blowing in them.

speed doc

Seats vents are off. It sounds like its coming from behind the rear straps/ storage area. I can barely hear it outside the car. Are the feul pumps loud in these cars? Just a thought.

speed6

I was looking at a 2008 sl55 myself and did a test drive at the dealer and noticed the exact same thing. I don't have much experience with these cars though so thought it was normal because the car is brand new after all but agree was a little bit annoying.

Chris-W

It's the fuel pump... I heard ti the other day on an 08 and went exploring...

JackStraw

There is also a pneumatic pump in the trunk that feeds the dynamic seats, the door locks and probably other mechanisms as well. It could be this.

Eurosport

+1
"some are louder than others" per techs

speed doc

The shop forman "thinks" it may be a vacum leak. Needs to remove some panels and "try" to find out what it is. Oh and by the way the top rattles like a childs toy. There is 100 miles on car. This will most likely be the first and last mercedes I will ever own. I just came out of a 2006 porsche that was like a rock and ran like a rolex. So far this has been the worst experience I have ever had with a new car.

JackStraw

I had a cracked vacuum line and it ultimately burned out the pump. The door locks stopped working as did some of the seat controls. It was a big job, but was taken care of under warranty. I don't think your problem is as serious, but you should still investigate.

speed doc

They have the car now in service. I just didn't expect this from a 140,000 dollar car. I had it a grand total of a day, now they said it will be a week. I wish I had just bought a turbo and called it a day. Maybe I'm just whining, but I am a car nut and this just ruins my taste for the car.

speed6

I told my salesman about the hissing noise and he had service check it out and came back that everything was fine. So I went in for another test drive and didn't hear it this time. The car sounded fine. Very strange.

JackStraw

Stuff happens, even in expensive cars. Hopefully this is the last of your problems. My cracked vacuum line was discovered early and I have had no other problems to speak of.

DFW01E55

Yes, you're whining. Even the 997TT has the odd lemon now and again, just check 6 speed.
I hope they find and fix the problem quickly.

speed doc

All is fixed and all is well. The dealer when out of their way to make sure the car was perfect. It was a vacum issue. The car is awesome, and I miss my porsche less and less every day. The low end torque is as addicting as cocaine.

bltserv

Good to hear you got everything fixed. These are after all very complicated cars with lots of systems. Once you get the couple little bugs worked out you should be fine. Just a little patience goes a long way when dealing with your SA / Dealer. Keep an eye on that roof. Normally once its adjusted right
it will not make any noise except on larger "bumps".

Enjoy