Hi guys,
I recently bought my daughter a 2007 CLK350 convertible. There are two issues I want to fix and I THINK I know the issues based on reading here, but I want to verify. Note that the car runs extremely quiet and strong at 1,000 RPM and above. No noises whatsoever.

First, this is a 272960 30 412622 engine, so I know it COULD have the balance shaft issue. It has 160k miles on the clock, so I would think at this point it was either repaired or doesn't have the issue. Can anyone confirm it should have shown up by now?

Second, it has a slight rough idle and sometimes the rpm surges in park. I can hear air (like a vacuum leak) under the hood but can't find a leak. I plan on just replacing the whole intake with a rebuilt one.

Lastly, at startup there is a rattle for a second. I suspect either the timing chain or the timing chain tensioner. Is it possible for the tensioner to just be bad and I can replace it, or does a tensioner replacement mean I need to replace the chain as well?

Pending Codes:
P0300 - Random Misfires
P0301 Cylinder 1 Misfire
P0303 Cylinder 3 Misfire
P0304 Cylinder 4 misfire
P2006 Intake Manf Runner Control Stuck Closed - Bank 1 (This I suspect is the rough idle cause)

All of these codes were before I replaced spark plugs and coil packs. I will rescan tonight.

I have a 2009 with then 85K on it and my Intake Tumbler Flaps were not working either because of a broken actuator arm. On the 272 engine there are 3 actuators in front of the Intake that run the Flaps. They get gummed up over time and become sluggish. If you're unlucky, the plastic arms on the devices break.

I replaced the entire Intake Manifold which got me new Flaps, Actuators and Flap Sensors. Hardest part of the job? removing all the connectors from the wiring harness so I had enough room to pull the manifold.

Thanks. That's what I plan on doing too. Ordered it this morning. $229 for all of it

I must have been lucky enough to get a Monday Manifold. NONE of the holes you see on top of the manifold were tapped on the new manifold. Luckily I had purchased a set of taps a while back.

Look closely at 9 o'clock and you can see the break. The rod that points downward is supposed to be attached.

I went the extra step and also bought a METAL kit to replace the plastic arms. I think it was around $18. As much trouble as it is to replace while the manifold is on the car, I wasn't going to have another one break.

Thanks for all the feedback. I got the rough idle fixed with the new intake.

I have ONE more question. Do they make a check valve for the timing chain tensioner? I have a tensioner on the way, just wanted to install the check valve too if they make one.