Many owners of late-model Mercedes-Benz cars equipped with 3.0 and 3.5l V6 engines (M272 or M273) have lately all been experiencing a universal Mercedes Benz intake manifold problem. Generally, they all report similar problems in performance, which include poor idle, loss of power, and a check engine light with the code P2006 (and sometimes others). The Mercedes Benz intake manifold problem is caused by one of the Mercedes inlet manifold flaps breaking, causing unexpected and supremely deficient performance depending on the orientation of the flap that has broken. To thoroughly understand what is going on here, first I want to describe what the Mercedes intake system is doing and why variable-intake-runner intake manifolds are becoming such popular engine parts in modern cars.
The intake runner is the tube going into the cylinder head that the intake air travels down to get to the cylinder. As the intake valve closes, the air going into the engine hits the back of the valve and ‘bounces’ back. The pressure wave will ricochet back up into the intake manifold until it hits the back, where it will bounce back down the runner. The trick is to have the pressure wave arrive back at the cylinder right as the valve opens, achieving the densest possible air mixture passing into the combustion chamber (picture a high-pressure standing wave right behind the open intake valve). To have this effect (also known as scavenging, or if you really want to get nerdy, Helmholtz Resonance) work in the RPM range you are targeting, you can tune the intake runners to be a very precise length. Unfortunately, scavenging only works in a narrow RPM range, so most engine designers build the intake runners to achieve this in a very useable RPM range. For a road car, this is around 3-4,000 rpm, where long intake runners promote a smooth even vortex. In a race car, engineers tend to tune for max power high in the RPM range, which include shorter intake runners for max flow.
A variable length intake runner manifold can switch between two sets of intake runners with a flap built into the manifold. This way, you can have one set of intake runners optimized for when the car is idling, and picking up low RPM speed. Then if you get on the throttle and request power for sportier or more demanding driving, the flap switches over to the second set of intake runners that is optimized for the higher rpm range. Many of these intakes also have specifically shaped flaps that cause a vortex, adding even more efficiency.
The most common cause of a Mercedes Benz intake manifold problem is one of the actuators for the variable system, causing the interior flap to become disconnected. Unfortunately, as the intake gets gunked up with oil and crud that comes out of the PCV system, the flaps have to work harder and harder. Usually, the Mercedes intake manifold failure comes on as the vehicle gets on in miles. The resistance on the actuators and flaps running this system (they are maintaining an airtight seal after all, so they are constantly moving along the walls of the manifold) becomes too much, causing the weakest part to break. In this case, it’s the cam lever in the center of the whole thing. Other parts can fail as well, including the Mercedes inlet manifold flaps, the actuator mounting arms and the vacuum diaphragms.
eEuroparts.com offers special intake manifold repair kits for these Mercedes manifolds that replace the plastic actuator cam with a metal part that is exponentially stronger than the plastic parts installed at the factory. It also costs several times less than the OEM Mercedes part and requires so little labor that a DIY fix is very plausible. In fact, even the beginner do-it-yourselfer could fix this Mercedes Benz intake manifold problem. Just be wary that many of the plastic connections (typically vacuum related) can be brittle. The part number for the kit is 103K10152 and you’ll find it in our Mercedes parts online catalog. Also keep in mind that if the arm does break and you replace just the actuator arm, the manifold will still be gunked. This can lead to other Mercedes intake manifold problems since the resistance on these components against the manifold wall will continue to increase unless you thoroughly clean the manifold out.
If you’re confident that will solve your engine performance problems, you should read the DIY step-by-step guide we put together on that Mercedes intake manifold repair.
I would go out on a limb to assume this is why Mercedes-Benz does not offer a replacement actuator arm, and instead requires the replacement of the entire manifold. The worst part is if you were to have the dealer diagnose and fix your Mercedes intake manifold failure, they would charge well over $1,000 for the Mercedes manifold assembly alone, before labor. We offer the Genuine Mercedes manifold for many hundreds cheaper than our competitors.
So, if you have an engine equipped with one of these manifolds, start saving up because these Mercedes intake manifold problems could happen to you. The repair kit (103K10152) is perfect for getting you out of a bind, it’s relatively easy to DIY as well. Just make sure to clean the manifold well before reinstalling to make sure the interior components aren’t hanging up.
Once installed, make sure to keep your PCV system clean and tidy, use only the highest quality oil, and change it frequently. This will ensure your intake system will stay clean, and your various moving engine parts will move unrestricted. If not, these Mercedes intake manifold problems can happen; yes, even on a Genuine Mercedes Benz Manifold.
UPDATE: Learn more about your options to repair or replace your Mercedes Benz intake manifold and also what your check engine light code means.
Here’s a tip from Mark, who did this job and has some words of advice:
“I do have to point out one major problem I found that was totally disregarded in any of the numerous written and video tutorials about pulling and replacing the Mercedes intake manifold (All were otherwise extremely helpful) and that has to do with dirt and grime falling into the intake ports during the removal of the manifold. No matter how much you try to keep things clean, I believe the layout makes it impossible to keep engine crud from falling in there. And I’m talking small sand and pebbles included. A disaster waiting to happen if not removed. I had been vacuuming all around the engine before and after I pulled the manifold, but the vacuum would not get anything out from the ports and on the valves. What I did find that works was to take an air gun, stick it way in, and blast around each valve numerous times, both dry and with some WD40 sprayed in there.
Make sure you have a wad of paper towel stuffed in each other port that you are not blasting, and keep another big wad in your other hand positioned right over the port that you are blasting to catch most of the stuff that comes out. Especially when blasting after spraying the WD40. It can be a total mess otherwise. Again, do this multiple times until you see that the valves and ports are totally clean. The area of concern beyond that is how clean can you get the cylinder(s) that happened to have its valves open when you pulled the manifold. I blasted that twice as much as the others. Don’t know what was actually left in there, and maybe it would have been a good idea to have pulled the spark plug so the crud had another way to escape, but so far the car is running well. I’m hoping whatever went in was either blasted out or pushed out the exhaust by now. Fingers crossed.
The result of fixing the Mercedes Benz intake manifold problem, as well as replacing its coils and spark plugs is a car that idles smoother than it ever did (50.k miles since bought) and so far runs great. Thanks again for your help. Hope my experience here helps someone else as they come across the same situation.”