Clicking Noise on M111 230 Kompressor (2000)

[V8steve]

I have a 2000 CLK which has a clicking noise when you touch the throttle and there is a change in the engine speed (backing off or slightly accelerating) .

The car has also recently failed its MOT With slightly high CO emissions 40odd whereas limit is 30 so suspect this could be the cause.

After the winter when I came to put the car on the road it had a misfire that I couldn't get to the bottom of I replaced the spark plugs (NGK BKR6ES), HT Leads, tried new coil pack (swapping out each coil pack with no difference) and replaced the timing chain tensioner. The problem was solved when I changed the Mass airflow sensor (a cheap unbranded one cured the problem). At the MOT the tester noticed the clip had come loose on the MAS and could feel a misfire at around 2000rpm. The plugs have been in for approx 2000 miles but unsure how long the MAS clip was loose for and whether this has caused the air fuel mixture to be out. Bottom plug is nearest the Timing Chain.

Any help is appreciated, if you need any more details please let me know. Thanks

 

[V8steve]

Recording of the clicking fault failed to attach

 

[gurpz]

Wrong spark plugs for starters on a 2000 CLK 230 Kompressor. As you car is on the changeover year the correct NGK plugs based on exact engine code should be:

M111.973/975 - BKUR6ET-10
M111.956 - IFR6D10

 

[V8steve]

Thanks I have now found out my engine is an M111.975

When I removed the above plugs I changed them for IRF6D10 based on another recommendation for a 2000 CLK230, are these are not recommended or not compatible for my engine?

Was you able to identify possible causes of the Clicking heard in the recording?

Thanks Steve

 

[Jobsworth]

You say you replaced the timing chain tensioner. It’s very important that the correct procedure is adhered to when fitting the tensioner or the chain can be overtight. It makes some odd noises if that is the case, and it will eventually snap one of the camshafts.

 

[V8steve]

You say you replaced the timing chain tensioner. It’s very important that the correct procedure is adhered to when fitting the tensioner or the chain can be overtight. It makes some odd noises if that is the case, and it will eventually snap one of the camshafts.

Yes I followed the procedure from WIS for the tensioner and put the spring in last after fitting and torquing up tensioner body first. The clicking is when the engine speeds up or slows down, audio recording attached to 2nd post. I'm wondering if it may be something vacuum actuated or the variable valve timing or the timing chain itself (if they stretch too much that the tensioner hits its limit (the old one wasn't at its ratchet limit))

 

[gurpz]

The noise is fairy common on many M111’s its caused by a faulty camshaft adjuster. Whilst the wrong incorrect spark plugs would not cause this I would still not run the car with the incorrect plugs. Worth getting the correct NGK BKUR6ET-10 plugs at the least. The noise is documented bellow:

Camshaft adjuster problem - MBWorld.org Forums

C-Class (W203) - Camshaft adjuster problem - Hi guys, I have c230 2002 coupe(2.3 L compressor) and a problem with a camshaft adjuster. Every time when the adjuster switchings from one regime to the other I hear some rattle for about half of a second (I posted a video with this problem recently...

mbworld.org

 

[V8steve]

The noise is fairy common on many M111’s its caused by a faulty camshaft adjuster. Whilst the wrong incorrect spark plugs would not cause this I would still not run the car with the incorrect plugs. Worth getting the correct NGK BKUR6ET-10 plugs at the least. The noise is documented bellow:

Camshaft adjuster problem - MBWorld.org Forums

C-Class (W203) - Camshaft adjuster problem - Hi guys, I have c230 2002 coupe(2.3 L compressor) and a problem with a camshaft adjuster. Every time when the adjuster switchings from one regime to the other I hear some rattle for about half of a second (I posted a video with this problem recently...

mbworld.org

Thank you, eventually light at the end on the tunnel! That certainly sounds like the problem I'm experiencing. I've now put the correct plugs in it as you suggested prior.

Are you aware if this problem affects the operation of the cam adjustment which I assume could also affect the emissions or if this is just something that can be "lived with" as the last post on the thread you recommended suggests?

Is it likely to have any detrimental affect to the engine & emissions if left in the long term?

Are you aware of any timing chain stretch issues/ replacement intervals as this is something else that another mechanic suggested which led to me replacing just the tensioner as the timing chain itself looked okay to me when I had the valve cover removed? I'd heard about the hydraulic side of the tensioner getting clogged so thought this was a wise precaution but hasn't made any improvement and the old tensioner when out looked to be in very good condition however the spring had noticeably lost some tension as it was slightly shorter than the replacement.

The car was driving beautifully before I was made aware of the clicking which obviously has worried me since with whether any damage is being caused to the engine so I've kept the car off the road since.

Huge thanks Steve