I've had my 06 for about 3 weeks. Since the day I picked it up, it has a cavitation like whining on cold starts that diminishes over a couple of minutes. You can hear it on warm starts but not near as bad. At the 1000 mile diagnostic check, I left it overnight so they could hear it in the morning. When I picked it up the next day, the service advisor told me it was the supercharger. I told him that was great news as up to the point I brought it in, it didn't have one. As he stood there silently, I asked if they had another 7 speed I could listen to as I thought it might be the tranny. Another service advisor overheard all of this and said it's a characteristic of the AMGs not the 7 speed. We proceeded to the showroom floor to listen to a CLK 55. It whined too but not as bad as mine. He said it was an oversized oil pump in the engine. I might believe that but after the supercharger comment, I'm a little light on faith with this bunch. Do any of you guys have this same noise on start?

 

I have had the same whining sound on cold start on my '05 SLK55. I never worried about it because it always disappeared after it warmed up. Don't know what causes it though. I have 6,000 miles on my SLK and I honestly haven't noticed it lately. Either I got used to it or it disappeared. Although the temperature here in L.A. had been in the triple digits for a week, so maybe that affects it. Next time I start it up cold I'll listen for it.

 

mine does that too. but just for abit after startup.. shouldnt be anything to worry about.

 

My car has over 6000 miles, too, and has always done the same. The colder the ambient temperature, the more noticeable it is. Over 75 degrees I generally don't notice it at all. When my car was on order, I drove another '55 that the dealer had in stock, and it did it to. I would describe it as sounding like a bad power steering pump.

 

i think its normal.... its the cooler fan or something maybe ?

 

Mee tooo. They said it was "normal".

 

It is true though...sounds like the supercharger on my friend's C230.

 

No, I don't think it's the cooler fan. Mine has a loud WHIRRRR as the pistons go into full blow on startup. Kinda like a second world war propeller fighter plane.

Usually the louder noise dies up within seconds, and then a lesser mechanical metallic noise dies out after 30-50 seconds as the engine gets hot enough. Seems to be a characteristic of the engine I believe.

 

i have 6800 kms on my car, it makes the same sound during a cold start. like sopme of the replies above, it is normal with this engine i was informed.

 

Thanks all. Breathing a little easier now.

 

Its the oil pump operating at high pressure at start up to protect the engine when it needs it most (cold...at start up). Someone said Supercharger? WTF? The SLK55 is a N/A powerplant . I'd whack that Service guy in the head for such an inane response.

This is a "good" noise. AMG hand builds the engines, but also designs them with long term reliability in mind. All AMG motors have whine a bit at start up (the V12 BiTurbo, the E55 blown versions, and the N/A SLK55s I have heard at least). I would imagine they all share ECU programming to ensure enhanced/high pressure oil pump operation at start up.

See ya,
-Matt

 

Hey Matt, you'll have to forgive me for being a little paranoid. I designed hydraulic power transmission systems for about 20 years and that sound is bad mojo in a HP system. I once saw a Bosch Rexroth hydrostatic transmission grenade while pumping about 400 HP due to catastrophic cavitation failure. When I took delivery of the 55 and started it for the first time I almost couldn't breathe. I'm use to it now and after the responses above truly believe that it's normal for this motor. This is my first AMG so I had no baseline.
As for the service writer, he now goes out of his way to help me. He's not wrenching it so WTF.