W140 clunking noise when in 3rd position of ignition.

[KLP 92]

I have just purchased a 1998 S500. I have a slight concern as when i put the key into the ignition and turn to the 3rd step (when the instrument lights light up) i hear a clunking noise twice followed by a skight whine which does not dissappear until started (well can't hear it when its started). I have looked in the engine bay and found out its coming from underneath the air filter covers. Anyway, removed those and found out that the noise is coming from below the air mass centre which is located in between the V of the engine. It appears to be sitting on the inlet vlave.
Does anyone know what the noise is? I'm having a guess it could be the inlet valve causing the clunking noise, but why???

 

[teky]

that will be the rotory idle valve and it does that its normal, it might need a spray out with some wd40 to clean it out they do get a carbon build up

 

[guydewdney]

under the MAS is the throttle - its probably setting itself

you can HEAR that from inside the car?? either you have very sensitive hearing, or im deaf.

eh?



take thew MAS off (one phillips screw / jubilee clip on the bottom - and watch the valve / throttle as someone else tuns on ign.

or go listen to another one.

 

[KLP 92]

I can only hear it outside the car. The flap underneath the MAS flaps up once and back down again when i put the key in the ignition. Its accompanied by a slight whining noise. The whine is coming from the same area.
Its just one of those things when you hear it once you just keep hearing it! I only noticed it when my blower motor wasn't working and i initally thought it was the motor making the clunking noise. Its very faint with the bonnet down but was wandering is it normal or is it something i should get seen to.

 

[guydewdney]

ill go listen to mine tomorrow...

 

[Merc600SEC]

Mine does same m8, I think its the ignition moduls, sounds just like a digital cam charging up when you switch to flash ?..I get the same clunks but only noticeable with bonnet up, still if it aint broke , dont try to fix it

 

[KLP 92]

Thanks for thst, put me at ease! Just one of those things you hear once and get paranoid about it! Thanks.