BostonSLK350

I have an 05 SLK that recently had belt squeal issues, fiarly minor. However the last couple days i noticed that if durring accelleration of increasing the throttle the car makes a strange vibration sounding noise. It has happened several time. The sound is more plastic on plastic vibration than a metalic sound but I am not sure what it could be. It also seems to happen when its a situation where maybe the transmission should downshift cause the engine boggs a little then once it shifts or the rpms come back up a bit the vibration and noise go away. Anyone have any ideas?

I read somewhere that the 350 engine has a variable intake of some sorts could this have anything to do with it? Sometimes this noise can be quite loud in the compartment.

quaidorsay

I've got a similar noise. My SLK350 is May 2006 build.

This is really strange, it started happening recently when I was given free fuel but octane 91. It was only 10 litres and I filled up the rest with Octane 95 and all it does is make this humming noise. Like as if the engine is electric hybrid or something. It rivals the sound of the exhaust at low speed/low accelleration.

I'm concerned. I am now trying to burn all the fuel in the tank that I have 3/4 full damn it, by driving around randomly.

I need to know if anyone starts hearing this noise.

Normally you'd hear this exact noise when you are in sport mode and accellerate hard and slow down/brake quickly, leaving the engine jumping revs down....

Now it sounds like a bloody robot.

Please advise.

Joey

Vodil

All we get here in California is 91 Octane. It could be a fuel pump noise caused by dirty fuel, but 91 Octane does not cause it to make that noise.

quaidorsay

91-93 in North America is like 98+ here.

In Australia we use RON like Europe, in North America you use, (RON+MON)/2 Which is a better measurement.

So putting in 91-93 means you are putting in some very high octane fuel.

I on the other hand got 10 liters of 85-89 (RON+MON)/2 in the system and so far it has had a hugely negative effect.

Hopefully I can burn it all off in the next couple of days, but so far after lots of driving it still hasn't gone away which makes me worry that it may have an engine coking problem.

Joey

quaidorsay

It was the idle pulley.

Remove belt, remove idle pulley, replace idle pulley, re-insert belt. SUCCESS!

No more sound, more power, just like new, all under warranty.

joey~!