Hey folks,

I have a 2011 E350 wagon with 135k miles and since I bought it 4 years ago it's made this clacking/ticking noise which comes from the (US) passenger side of the engine, at the front. From what I've read it's a pretty common issue with these engines but no one's figured out the problem or fixed it. I've never been one to leave well enough alone so I keep diving to see if I can track down the noise.

Not my car, but this is the same noise:


To recap, this noise happens once the idle drops to its lowest RPM. When you rev it just a little, the noise goes away. There aren't any known failures associated with this behavior. I've replaced the oil pump with no change and others have inspected and changed the various lifters and such in that area and found nothing remarkable.

Earlier this year I did some probing with a stethoscope and narrowed down the noise's origin to the VVT hub. I've heard of the locking pin getting stuck or its hole wearing out so I bought a Febi hub and oil control valve (2720500578) and swapped them out. Procedure went fine, but the noise persisted.

I did some testing yesterday with my Autel scanner and found a few interesting things.

• Unplugging the cam magnet and cam sensor at idle did nothing.
• I applied 12v to the magnet and confirmed it's moving freely.
• There was a fair amount of oil on the magnet's harness connector. The magnet was replaced several months ago, but the oil may(?) be left over from the prior one which was replaced about 3 years ago. I cleaned it off and will check to see if it comes back. All magnets I've used have been the updated part number (2720510177). It's had the small protection harness on it since I bought it.
• I performed the magnet actuator test via the scan tool and it worked perfectly, returning values perfectly within the range.
• I noted that this camshaft position is the only one where the magnet connector points to the side (left) instead of being vertical. Could be coincidence, but interesting.

The big thing I found, though, was the camshaft position values. Note the other camshafts never varied more than half a degree or so, very steady. The passenger exhaust camshaft, however, varied by 2 degrees and would jump all over the place, occasionally out of the allowable range (> -19*), but always only for a moment. I did get code P0014 thrown months ago which prompted the second magnet replacement so it hopping out of range lines up with that code. My guess is that 99% of the time it never goes out of range enough to trigger an actual code. I realize varying by 2* isn't a whole lot and normally nothing of note, but the fact the other three cams are so steady and this one isn't and it's the one making the clacking sound is pretty noteworthy.



This raises more questions than answers for me. What could be the cause of this behavior? The ECM having problems due to oil being wicked into it years ago is possible, but the problem didn't change when I unplugged both magnet and sensor, nor did it manifest on other cams when unplugging them. I know the official Mercedes line for the cause of the noise is "cylinder scoring/piston slap" but I've scoped the cylinders (and saw them from below with the oil pan off) and they looked great. It could possibly be an oil pressure problem where that hub has enough pressure to unlock the pin, but not enough to keep it from flopping around, but that's a guess.

Any advice on what to check or try next or ideas what could be the culprit would be appreciated!

Thanks

 

Based on rpm speed, it sounds like lower part of the engine, not upper distribution.

I am going to go with worned out piston pin. You hear it every time that piston turns around.

Use better lubricating oil and a bit more viscosity too. I'd mix some 50 within the 40 - I know we're not supposed to but choices are few

What oil was used on this engine ??

 

Did you replace the pulse wheel when you did the actuator and bolt/valve? WIS says it must be replaced every time, I'm not sure why. I also have a P0014(?) that I'm going to tackle this winter for the passenger exhaust camshaft position. 186k miles. There is a guided test in Xentry that compares all 4 cam positions with a graph (I'll post it next week) and this is the only one to fail. All magnets were replaced 2 years ago. Xentry says to replace the adjuster, however myself and some other techs think it may be the valve sticking, so I'll try the valve and pulse wheel before I replace the adjuster for $500+. (You can buy a low mileage m272 engine for $1500 or less!)
Other thoughts for you and your 2 degrees- this side of the engine has the chain tensioner. Maybe the slack and tensioner moving at idle causes the deviation your seeing. First thought would be the intake cam would also show the deviation because of it's chain driven and the exhaust runs off a gear, but think about the exhaust adjuster and the narrow spring loaded teeth section designed to take up any gear lash. Maybe it's moving back and forth itself as the chain goes in and out of tension at a low idle speed?

 

I totally agree that's what it does sound like. I checked all of the rods for looseness when I had the oil pan off, though, and everything was nice and tight. Cranking it over by hand should produce some clicks if that were the case, right? I can give that a try and see I hear anything.

I've always used Mobil 1 0w40 Euro Formula. It's occurred to me that using something a little heavier might help, but never got around to trying it for one reason or another You're saying mix some 0w50 with 0w40? If just using another oil is the solution I'm happy with that.

I did replace the pulse wheel, yes. It's because the little locating pins on it can shear off if it's reused. I'm very interested to hear how things go for you! I'd be willing to bet we have the same issue. You're right about the low mileage engines too... then of course you could end up with one that does the exact same thing

Regarding the spring-loaded teeth: I don't understand how that's supposed to work. The width of the gear is sort of sliced in two and each section is supposed to be able to move independently of each other but once the teeth are meshed with the intake hub, there should be zero situations where they would, right? The intake hub gear is solid. Unless maybe there's slop in the teeth which you would think wouldn't last long.

 

If it were the wrist pin, wouldn't the noise get worse as you rev it up? It completely disappears when you rev it up just a little.

 

that is good news!
I means low oil pressure at idle is starving the furthest away path.

I remember reading a similar story and the owner rebuilt his oil pump thinking it was worned out.
No improvement...

I think the issue is too much leakage along the way.
How old is your chain tensioner??? On M276 it built to leak pressure when extended.

Below is my favorite old engine milk, I am usually not a fan of snake oils.

I'd use only one quart bottle of this in preferably the 10w50 or 10w40 "high mileage" type.
it has anti-friction additives that engines love beside a bit of viscosity bump.
Include that within your normal engine oil. One quart is not too strong.
Results with 1K miles or less.

 

lol yeah that was me who replaced the oil pump. Oh well, the oil pan and diff needed to be resealed anyway...

Chain tensioner is new. I replaced it when I replaced the exhaust hub and valve.

Cool, I'll have to give that a try next oil change. Were you having this noise as well, or was adding a quart of that preventative?

 

I was thinking about replacing the chain tensioner, glad you already tried that with the same results. 😏

 

@atraudes - I think I have a problem very similar to yours. I would even dare to say that is the same - considering the engine specs, the things and procedures you have followed, etc. Have you managed to find the root-cause for the ticking noise yet?

 

It wouldn't surprise me, it seems to be a common issue. No, unfortunately I haven't made any headway. Life happened and I haven't had time to do much of anything on the car lately. I'll post back when I have something, though.

 

I used one quart of 10w40 high mileage that you have pictured in my last oil change and no change after a thousand miles

I'm going to get my hands on an oil pressure gauge and hook it up to the testing port on the engine. It'll be interesting to see what happens!

 

I'm back with the same problems and a check engine light which is coming on with increased frequency. I installed a new OEM pulse wheel and control valve on the RH passenger adjuster. The old valve felt notchy when pushing it by hand, so it was worth a try. Not a bad job- I've managed to get it down to 2 hours or less. However, even after clearing the faults, and re-learning the camshaft positions, I have the same fault codes.

I had access to a free 2006 260k mile m272 which had a faulty balance shaft and finally skipped and broke the chain. I took both exhaust adjusters off the motor and proceeded to take apart the LH side and inspect for damage, thinking to use the RH side on my engine, which I did, with the same results and fault codes p0014 p0015 incorrect position of the exhaust camshaft.

Some interesting things I learned so far. You CAN take these adjusters apart. I don't know what DANGER the stamped warnings refer to other than the snap ring flying off, which never happened to me. There isn't much going on inside, and my original adjuster and the 260k mile adjuster showed no obvious signs of damage. You must use a paint marker to maintain the proper position of everything. The large snap ring that tensions the thin toothed gear is difficult to reinstall. It can also be left pinned in place while removing the actuator cover. What I did notice though, is my orig. adjuster when disassembled the vanes can easily be rotated back and forth inside by hand. However, the LH 260k adjuster was "tight" and required a tool to wedge between the vanes to get them to move. Wear and debris pattern inside showed that it wasn't stuck, it was moving when on the engine.At the moment I'm working under the theory that this "loose" adjuster causes the variation of advanced/retarded camshaft timing that your scan tool sees, as well as my Xentry (DAS , really) graphs show below. The only way to prove this is to swap left and right adjusters on the same engine. I don't want to do that extra work at the moment, so I will reassemble the 260k mile "tight" LH adjuster and install on my RH bank. I will then diassemble the 260k RH adjuster and see if it's loose. I will also be looking carefully at the chain teeth on the INTAKE adjuster for excess wear.

 

Here in two of the graphs you can see the RH camshaft position shown in GREEN does move fully under command, however at a steady speed you can see it misbehaving +- of where it's commanded to be. The RED line is the commanded position and BLUE is the LH exhaust cam position. Note the LH position is very close to commanded position. I have also swapped the solenoid and position sensor as well as cleaning the plug connections and removing the sacrificial short harness to eliminate any of these as a fault. The green line going above and below (advance/retard) correlates with my intermittent P0014 and P0015 codes. The CEL seems to only illuminate after a certain fault range and number of adjustments has been exceeded. I can find little information about the camshaft adaptation values but I suspect a slightly stretched chain which is being compensated by the tensioner on the RH bank is responsible for these numbers. It seems the adjusters can be adapted by the ECU to adjust to a 0 degree initial position of the camshaft.

 

Here you can see my original RH exhaust adjuster misbehaving badly. I'd love to just install a new adjuster, but for $600 for an MB reman it's not happening just yet. I have been considering a new aftermarket adjuster, for around $100 however.

 

E55Greasemonkey: bravo! That's some excellent information to have. So what you're saying if I understand correctly is the ECM is instructing the pass. side adjuster to move certain ways, but it's not moving in the expected manner. Whereas on the driver side it's moving as instructed?

I swapped out my adjuster for a new Febi one but absolutely nothing changed, so I can't recommend it. That said, I wouldn't blame you if you wanted to try anyway. When I disassembled the old adjuster it also looked fine, no damage or weird wear.

I have a bit of a finding myself. While I was under the hood this weekend changing oxygen sensors I got a chance to check out my ECM. I've been wondering if oil getting into it via the cam adjusters is causing it to malfunction. Sure enough, the entire engine control socket had a thin layer of oil everywhere It's kind of tough to see in the picture, but the pins should be bright silver, not the dark color they are. I wiped some of them with a q-tip and it came out stained with motor oil.



So, I'm thinking the oil is causing the ECM to have trouble controlling and/or monitoring this exhaust cam. I think I'm going to buy a new engine harness and open up the ECM and spray it down with electronics cleaner the best I can and see where that gets me. Worst comes to worse I can always buy a new ECM but I know they're far from cheap. Mercedes recommends replacing all of the sensors and such that are connected to the engine harness since they'll all likely be contaminated too, so I'll probably do that too, and check things like the spark plug coils to see if they need to be done.

Thoughts? I'm curious to see what your ECM connectors look like too.

 

You may be on to something here. I did have a slight trace of oil in my camshaft position sensor for the RH exhaust cam, which I cleaned about a month ago. Last night when I saw your post, I checked my ECU and although the pins didn't look too bad, there was clearly oil residue on the connector side. You can see the comparison of the color of the black plastic on the engine side of the harness (left) vs. the body side (right.) I've saved quite a few m276 engines with this problem by cleaning the connectors and ECM pins (never needed to open the ECM) but I've never seen it on a m272. So I cleaned everything with contact cleaner and compressed air, holding the ECU upside down so no fluid would run inside of it. Cleared the code, and guess what- I drove around all day with no CEL! Prior to this, I'd get a CEL within the first 2 drive cycles. I did unfortunately get a pending (stored) p0015 code by the time I got home....however that started happening over a year ago but no CEL until this year. So something has gotten progressively worse which is also a clue to all of this! But something definitely changed since I cleaned the pins last night.. So the theory now is...either the cam is adjusting properly, but the sensor is not seeing the position correctly, or vice-versa. I'm somewhat convinced the adjuster is not the problem. The other possibility is an oil pressure issue at that adjuster, which is tricky to verify.. Next steps for me, will likely be to run new wires outside of the engine harness between the position sensor and ecu,which I'll try first since it had evidence of oil at the sensor, and then the cam magnet/solenoid and ecu, thus eliminating or proving oil contamination in the wires is causing a fault. I'll start working on a temporary harness this week.

 

I'll only need to run 1 external wire to each of the position sensor and the solenoid, as that would be the signal wire. The other wire(s) are power or ground and are shared with several other sensors so we know those are good. Here you can see a mistake in the wiring diagram showing two y49/7 exhaust adjusters when one should be a y49/6. But that's easy to figure out by looking for the wire colors on the engine. The solenoid PWM signal is controlled by the ground, which is typical. B6/7 is the RH exhaust cam position sensor.


ME9.7 pin layout

 

A quick update I'm going to scope and compare both exhaust cam position sensors at the sensor thus bypassing the engine wiring harness without having to take any wire pins apart.

 

It's really cool to hear that just cleaning the connectors made a difference! Good thinking with measuring values at the source and running temporary wires. I'm anxious to hear how things go. I think I'm going to order a new harness regardless since oil in places like that is just not kosher. I priced it out and I can get one for about $500 which isn't too bad.

I know they have protective pigtails for the cam adjuster magnets, but do they have any for the camshaft sensors? I've heard of (and seen, IIRC) those leaking into the wiring as well. Probably wouldn't be too hard to order the connectors and such and make some on my own. Doing the same for the crank sensor might not be a bad idea either...

 

Ran a new wire to the position sensor today. Initial testing looks like this won't resolve my issue. I'm learning more about the test pattern and function of the adjuster. Again looking at the green line, up is advanced down is retarded. The last peak to the far right was a quick stab of the throttle. You can see it's slow to return. On deceleration due to lower oil pressure and moving against the direction of rotation the coiled return spring inside the adjuster assists with retarding the cam position. This adjuster I believe is too tight internally or the spring is weak and you can see the pattern in the test as it's taking too long to return to position. The advance is working perfectly as seen, because of the increased oil pressure as the rpm's increase as well as the direction of rotation of the adjuster.

 

I dunno, if it was a spring problem I would've expected when I installed the new adjuster that I would have gotten some sort of change, but it was exactly the same. A new wire running to the adjuster might be worthwhile.

I have my new engine wiring harness and I'm just waiting for a few remaining sensors to arrive. I'm hoping to get that installed in the next couple of weeks, but I know better than to expect any miracles. Opening the ECM and giving it a good cleaning and inspection feels like the next step beyond that.

 

Well I ran a dedicated wire to the solenoid as well yesterday, and had the same check engine light come on today. It's either the adjuster or the oil pressure. I found a used 78k mile adjuster for $70 and will have it here in a few days to try.

 

Installed the used adjuster today, it looked to be in excellent condition, very clean, and the CEL came on within 5 miles of driving, P0015 again. Really frustrating, not sure what else the problem can be, maybe an oil pressure issue on deceleration. Even though I swapped the solenoids already, maybe I'll just try a new one. However I now suspect an oil pressure problem, my m272 has that cold start thump-thump common to these engines built before 2009. The remedy is to install tighter upper main bearing halves. Back when these cars were new MB said it wouldn't cause any problems, fast forward 15 years and 190k miles and I think differently! My engine also feels "rough" when accelerating even though I replaced the mounts. I've also got a slight crank pulley wobble that I haven't seen on 15+ other m272 I've looked at. 2 new OEM crank pulleys didn't fix the problem, I believe the crank is worn or bent. I'm not convinced a new oil pump would help either, I think the oil clearances at 190k miles is the issue. Normally I don't worry about CEL's on old cars however this one causes a 2mpg economy hit, and worse, I've had a few instances of delayed 2-3 sec throttle response when trying to pass after the CEL comes on and it's left me in some scary situations. Maybe time for a lower mileage 2010+ engine swap.... something I'm not really excited about.

 

Here is the WIS document explaining the camshaft adjustment, take note of the paragraph referencing oil pressure and temperature in regards to the exhaust camshaft adjustment:

 

I'm happy to report that my 2008 ML350 with 191k miles is now officially fixed. Although this thread was originally about a ticking noise and erratic cam position,what started for me 3 years ago as a stored code P0015 and then later progressed to a monthly, then daily check engine light has been resolved! I've been driving 3 days with no codes and passed the exhaust cam position graph test. Yesterday I installed a new OEM MB magnet on my problem RH exhaust bank. This was the final fix. I had previously replaced all 4 magnets with OEM MB parts only 3 years and 22k miles ago. I've replaced probably 200 or so of these magnets on customer's cars without a single repeat visit. For anyone reading in the future, I learned a very important lesson here. Even if you recently replaced the camshaft solenoids (magnets) DO NOT assume they are still good. Also, swapping the magnets from intake to exhaust to see if the fault moves DOES NOT prove the magnet as good or bad as I found out. I suspect the intake cam actuator moves differently, so a magnet that is bad on the exhaust side WILL WORK fine on the intake side.

What I have learned:
I was able to re-pin the Ebay adjuster teeth without disassembling it. It requires two people and a very large pair of snap ring pliers (18" long), along with a metal pin to hold the initial spacing before inserting the lock pin.
My original RH exhaust camshaft adjuster was bad. It became "loose" over time causing a rapid fluctuation between advance/retard as seen in my previous post. This caused two codes; p0014 and p0015. My adjuster oil control valve (bolt) felt notchy and was the first thing I replaced alone with a new OEM part.
The used 260k adjuster was too "tight" You can see the lag in the graph previously posted where it was advancing but not retarding. This caused only one code; p0015; p0014 never returned.
The used 70k miles adjuster was just right; however p0015 continued but the graph was looking much better.
Installing a new magnet eliminated the p0015 and now the graph looks good when compared to a known good ML350 with 90k miles.
Disassembling the magnet showed no failures. I found some sludge inside, but the pin still moved freely back and forth.

The final graphs below are the same test but run for different lengths of time. You can see the blue and green (LH and RH exhaust) are now synced; the red is commanded position by the ecu, there is some lag displayed between command and movement, this is normal.