Engine noise

[Max c230k]

Went to drive the car today for the first time in 3 weeks (the wife hogs it all the time!!) and heard a noise coming from the enging which can only be described as sounding like a frog under the cam cover.
Got the stethiscope onto it but cant really pinpoint its origin but after a bit of fiddling around it seems more like a bad bearing vibration which kicks in at about 1500rpm and goes away at about 2000rpm.
Ill be taking off the cam cover tomorrow for a proper inspection but just curious if any of you guys have experienced the same problem or know of any common faults before a go pulling my hair out over it.
cheers!!
Oh, im driving a 1999 C230 Kompressor Sport......

 

[BlackC55]

Sounds like the camshaft actuator at the front of the engine. Pull the cover off and disconnect it wit the engine running and give it a blip. If the noise has gone you know its the actuator.

 

[hmang]

hey black...camshaft actuator..? what does that do ?...just being nosey !

 

[BlackC55]

From memory...... Advances the inlet cam. Cheap version of variable cam timing.

 

[hmang]

some sort of centrifugal, bobweight affair ?

 

[BlackC55]

electro magnetic affair

 

[hmang]

i'd like to see one of those

 

[C220GJS]

Here you are,camshaft adjuster;http://www.detali.ru/cat/oem_mb2.as...GM=717.460&CT=M&cat=19K&SID=05&SGR=030&SGN=01.

 

[hmang]

interesting.
thanks guys, another thing i've learned

 

[Glenn Smith]

From memory...... Advances the inlet cam. Cheap version of variable cam timing.

Not a cheap version at all, it is variable valve timing, i believe they are prone to failure occasionaly and do rattle if affected.

 

[Glenn Smith]

works on oil pressure, the cam and cam drive sprocket are connected via a worm type drive coupling, a solenoid operates at a certain engine speed, this moves a piston using engine oil pressure, pushing the worm drive and advancing the cam timing.

 

[Max c230k]

So where is this camshaft actuator??
Went back to basics and checked for all the obvious things for noises but had no joy so took the cam cover off and the noise is definitely coming from the inlet side of the back cylinder (4).
Cant see anything obvious and all the buckets are strong under pressure.
Gave the enigine a good flush and replaced the oil but it actually seems worse than before.
It really sounds like a small end bearing noise but with 102k on the clock and a full dealer service history can my trusty merc be giving up this easily??
Any ideas guys and am i missing something before i go pulling the heart out my motor??