Rattle On Idle

[FunkyFez]

I'm starting to tune my ear into my C43's 'character rattles and squeaks'.
The most recent has been a rattle on idle. It's not a tappety or cam related sound, it just seems like something needs a tighten. It's not present when the car is cold i.e when the idle is slighly higher, just when it's warm.
Saw a thread on the idle pully that looks like that may be the issue, but still not quite sure. Any thoughts before i get the old girl booked into my local indy.

 

[stevesey]

Try the purge control valve (normally front right of engine bay under ABS unit on a 202 with MOT written on it) often ticks once warmed up. Grab it and you can feel the vibration. Also the noise doesn't vary with engine speed.

 

[FunkyFez]

That seems to be 1 of the sounds that i'd pinpointed, so it's 1 to tick of the (thankfully short) list.
The steel belt at the front of the engine that drives the alternator, fan and various other bits and pieces was another area that i thought i'd heard a rattle, but there seems to be little play in it. It is relative to engine speed so i think i'm looking in the right area. I can't pinpoint exactly where the noise is coming from and it's getting on my wick.
Paranoia.....don't you just love it!

 

[lynall]

My v8 E430 makes a few noises, new oil and filters etc still the same

When hot remove the rocker cover very little or no fumes equals a good motor.

The injectors themselves make a lot of ticking noises as they are fired, stick a screwdriver on one with your ear on the handle and have a listen.



Lynall

 

[Smiley]

Has this engine got the same sort of serpentine belt tensioner assembly as the in line engines? It is a shock absorber device mounted on a plate - when it wears it makes an awful noise gradually getting worse and worse - its really irritating - but quite cheap and easy to change.

 

[chatteris]

my c240 rattles sometimes I think its in the clutch on the aircon compressor its usually idling when hot when it is most noticable and usually stops if I turn aircon off

 

[FunkyFez]

Had my local indy take a peek under the bonnet and it seems to be that 2 of the drive belt tensioners have seen better days. He also reckons the water pump is noisy as hell.
Just need to wait and see what the financial damage is to put it straight.
Thanks to all for all their advice and suggestions.
Still loving the Benz!