I drive a 2012 E550 / M278 engine. About 2 weeks ago I had a check engine light come on. Took it to my Indy Mechanic and said it was related to one of the turbos (Garrett Turbocharger MGT1752SL Left Side or Garrett Turbocharger MGT1752MS Right Side). He could not find anything specifically wrong and so reset the codes. I've been driving since and the light has not come back on. Nothing has felt different or any change in the characteristic of how the vehicle drives so I hope it was just a fluke.

For anyone who has had a failure of the turbo before, at what mileage did it occur? I have been regular with the oil changes and other fluid changes. I am hoping my turbos last much longer but want to get a sense of the turbo reliability.

Any advice on how to increase the life of the turbos?

 

It is no doubt boost, because the car cannot tell if the turbo fails, it can only see if boost is not up to snuff.
For most people the cause is the check valve for the turbo vacuum, which will fail at some point. If you haven't changed yours, it's likely that.

Other fails can be the turbo solenoid or a bad/leaky vacuum line in there somewhere between the the check valve and turbos. I have a Rat problem and they seem to gravitate towards those vac lines so they've killed my turbos many times. So much so that I replaced some of the plastic line with steel line, and wrapped the rest with steel wool, and so far so good.

Another fail is over boost, which will kill the power to the solenoid and thus kill boost. It's not hard to over boost, the question is if the ecu will complain. For example; if the check valve is bad it'll let oil into the vac line, and if too much were in there it'll slow down the wastegate actuation. If this happens at the wrong moment; over boost. Even when everything is working right I believe it's on the edge of triggering over boost under certain conditions, so I suppose it's possible your turbos push that over the edge? Just a guess, but I'm leaning heavily towards the check valve.
If you over boost and the ECU kills the turbos, you simply restart the engine and they're back. Over boost never gave me a CEL, just a code. Under boost gives a CEL. Since you have a CEL, low vac is my #1 suspect.

The check valve is easy to check. It's on the vac pump behind the left head, can't miss it if you follow the vac line. Pull that for a visual. Somewhere here is a post on it, where the OP bought a chinese valve, which I'm against, but the post will have good info in general.

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Edit: Not the thread I was thinking of, but it has good info: https://mbworld.org/forums/w212-amg/...-repair-3.html
Fyi I would not improvise by using other valves as some there suggested, because the the oem valve barely works well enough (imo) so best to not make things worse, which the other valves will.

It looks like Prihadi (post 62) found what looks like a good valve? Hard to tell unless I had it hand, but looks better than the black chinese version. I wanted peak vacuum and was unable to find a good valve, so I bought a whole pump just to get that teeny weeny bit of rubber. No doubt cost me it's weight in Gold, but power is gold, is it not?

 

I talked to the mechanic, he told me it's underboost that caused the CEL but he also said he did test the check valve and it tested within spec. If any other theories on what could trigger underboost let me know. Thanks.

 

YOU SIR HAVE THE MIDAS TOUCH! always getting all you can out of your machine, i applaud you 👏

 

My 2014 e550 m278 c207 has a recurrent low boost condition. It has proven not fixable via check valve or solenoid replacement. I have not replaced the vac lines to wastegates however they appear intact.

I have 135k mi or so, issue appeared around 120k mi. I plan to replace turbos with gently used set from an m157.

just fyi

 

I would ask how he tested the valve. Well, I don't need to because I know he didn't check it well enough. My motto is never trust anyone who is taking your $. It's like a girl after prom trusting a guy because he said "I love you." A mechanic also has but one goal; which is make $. Want it done right? Do it yourself. I won't even trust anyone to do an oil change. Even tire changes I have to watch them, because they find every possible way to F that up too. Set before last they put one tire on backwards. They always over pressurize, and rarely is the torque anywhere near spec. Lube the bolts? Never seen it, unless I do it myself. I could go on, but the point is you will most likely need to fix this yourself, and odds are it's an easy fix, especially since you have a variety of people here that have been there.

So the valve, if he checked actual vacuum, I bet $ he did not check at rpm. So you need to take the valve apart for a visual. If you see some of the many fail pix online you'll see some broken ones may still work to some degree, maybe even most of the time, but I doubt any would make good vac at higher rpm. So unless it's been removed and verified intact, I'd assume the worst. If yours is oem I'd say it's toast, or about to be, just like if you still had the oem serpentine belt. My valve wasn't bad btw, but it was old enough that I knew it would fail at some point, likely when I have a super rare opportunity to race someone. Not just that, but the likely degraded performance as it breaks apart leaving me wondering wth? So I replaced it.

When I was having boost issues I suspected the solenoid, so I measured the vacuum after the check valve, and after the solenoid. You can plug a gauge directly into the rubber dealies on the tubing, but I made a "T" to a gauge that I ran into the car so I could watch it as I drove. The vac from the pump was excellent, which I forget exactly since it's been years, but I believe 27"? Then after the solenoid it varied drastically since it's modulated, but I think it peaked at 25" when it wants to. So that's what I'd look for, at all rpm.
Example of a fail; I replaced the solenoid with a brand new one and tested it. I think that one peaked at 15"? Whatever the # it was a hard fail. The solenoids are crude devices imo, and I'd wager they all read different. I think anyone wanting peak power should check them. For example; even with more vacuum than oem (because I have since modded it), the vacuum cannot hold the oem wastegates closed above a certain rpm. I think it was 4500 but again it's been years. Point being that any loss of vacuum whatsoever means my wastegates are open even more. If someones car came with a crappy solenoid like my new one, they could likely tune it or add bigger turbos and never make much more power than stock. So that vacuum is super important. Your wastegates might need more vacuum, maybe less, who knows?
So if this mech found nothing, and we ***-u-me he checked vac at idle, leak checked all the lines, and actuated/leak checked the diaphragms, (all of which should be a given with this issue) then you really need to do a visual of that check valve. If you've never replaced the check valve, I'd order one now. Either way I'd order one now.

Now that you've returned after ordering the check valve, per previous instructions :p
Another check you can do is look at the solenoid duty cycle. If you have an app or something to do that, if not it's ~$15 total to make it happen, I can explain if needed. Then you can see if the ecu is trying to make power but something mechanical is not cooperating, or if the ecu is pulling power. My issue was the ecu was pulling, and yes it was so bad it could trigger a CEL. I think I may be the only person on the planet with this particular issue, but I tend to have never heard of issues. Most everyone else, it seems, is because of that check valve. Then a variety of people have had a vac line pop off, or one break or crack (or Rats chew it like me), or misc other fails related to vacuum. Yes some actually had bad turbo, but I'd assume your tube is not only new, but has better bearing and wastegate so failure is low on my suspect list. Not gone, but vacuum valve is way way higher on said list.

Edit: above applies to you too Jaybird. I'd verify the actual vacuum and check the diaphragms for oil. Replacing turbos is a big job so I'd rule everything out first. Unless you just want the 157 T-bos, then this is a great excuse.

 

Wow, that Chevota post is packed with great information. I never heard about greasing wheel lugs. I suppose it could reduce the onset of oxidation, or make the lug nuts easier to loosen when changing a flat.
In any event, when I read the symptoms, of your turbo acting up, and not providing boost, I immediately thought of coking. Coking in a turbo is a result of improper cooldown. Always allow your turbo to spin down, and cool off for 2 minutes at idle. The manual may say 30 seconds, but why chance it? If you plan the last part of your errand, going into parking, just slow down early enough so that you can get into your parking spot 2 minutes after you start idling in gear. That’s what I do. If I ever get a coking problem, it won’t be from my failure to ever do a proper cooldown. It really only takes 1 time of shutting down the engine without cooling to coke the bearings. That’s also the reason I disable autostop.
Autostop won’t necessarily cause coking in a situation like stop and go driving in bumper to bumper traffic. But if you are sprinting in autostop from red light to red light, you are asking for trouble.

 

Hmmm, didn't know the M278 also suffered from this issue.

 

@Chevota

Is this the right part? Should I buy two of them, one for each turbo or is there only one vacuum for both?

 

I would get the orange one in the thread I linked. Because the black one lame imo. The orang one looks better but just a guess.

 

ibbij: I just re-read your latest post, and it only has the one check valve. It feeds one vac line that feeds the one solenoid, then after the solenoid the vac line splits to the two turbos. The lame black chinese one may be capable of stock boost, I don't know, I just know my valve is probably as good as it gets and it still can't hold the wastegates closed, but I'm asking for more than stock boost. When you said Garrett I assumed you meant aftermarket turbos, thus newer and probably with ball bearings, but yours are stock aren't they? So while I still suspect the valve, it increases the likelihood of a bad turbo. I'm waiting for mine to give up the ghost because I abuse them, but somehow they're holding up. When one turbo seizes you lose all your boost because the good turbo just dumps the air out the bad turbo. Fyi. Just had a thought; I wonder if the air pressure sensors in the air filter box could see that? I'd imagine the pressure delta would be very small, but if one drops a hair and the other rises a hair... At the very least it would interesting to see if they can pick it up.

MB2timer: Lubing the lugs is not common, and I never understood why. I remember battling lugs as a teen, and misc people breaking them, and wondering why they don't lube 'em? So I started and now removing any I've done are like butta. I usually use copper anti seize, but have used grease or motor oil when I'm lazy.
None of the Benz lugs I've had were corroded, but there were several where the tire guy thought the torque was 900ftlbs instead of 90. Maybe an exaggeration but I've had to put all my weight a breaker bar to break 'em free so I know it took >300. No I do not weigh 300, my breaker bar is ~18" long. It's usually just one bolt that's like that, and if I had to guess I think it's from tightening the first one with the impact, then as the others are tightened it puts more tension on the first? Just a theory, but if they impact all of them then what else could it be? I torque them like a normal person, or what I think a normal person should do. Hand tight using only the socket to snug the wheel flush to the hub, wriggling and centering it as I go. Then maybe half tight, then all the way. Never used a torque wrench though, because I'm a redneck.

My turbos work fine, it's the programming that's my problem, which I bypassed and prob solved
I'm not an expert on turbos but I thought coking was more or less a thing of the past thanks to syn oil and water cooling? The OP on the other hand, maybe? I've seen M278/157 turbo water lines online that were mostly, maybe totally, clogged. Who knows that does after a few years?
I don't idle after I drive because they're never really hot by the time I stop. Meaning I'm always putting before I park, plus my exhaust temp is cooler than stock at idle, as are my water/oil temps Oh, I also have the oil solenoid unplugged, so a little extra oil flow/cooling at idle. The only thing I do worry about is too much boost when the turbos are too cold, so if I do gas it cold, which is just about daily, it's just for a second. Not sure how long is safe but pretty sure one sec is fine.
I do often wonder what the water is doing when floored. Without a positive displacement pump I picture the water jacket is just a violent steam room that won't let water in, excluding enough to make more steam.

I hate that Eco stop function! HATE! I disabled Eco with that Launch X431 tool that's popular for MB. Is that what you did? I also used it to change the turn signal to old school, meaning no more automatic three blinks, which is also a pet peeve for me.


W205C43PFL: I figured any brand of car/model with that kind of valve will have that problem. After holding one in my hand to see how delicate it appears, and seeing all the destroyed pix online, I'm impressed they last as long as they do.
One thought my brain generated is to use the brake vacuum, but then I wonder why they didn't do that in the first place? My only thought is it's not as good, which I'd imagine is because it's check valve is more robust and thus less efficient. Another thought is to add a little tank to store vacuum. The diaphragms take some time to suck down so a tank could speed that up. Maybe it won't make a difference, maybe it'll cut lag in half, only one way to find out. I did reduce lag already by adjusting the duty cycle on the solenoid. That, btw, is an easy way to overboost at part throttle and the ecu will turn the solenoid off. This is why I'm so familiar with the overboost function. It only takes ~2-3 psi of boost when you shouldn't have boost to trip it. I'd turn the overboost function off but I don't know how >: |

 

Yup the engine oil also slowly disintegrate the rubber.

 

ibbij; curious if you figured it out or made any progress yet?

 

Thanks for checking back in. The CEL has not happened again after my mechanic did his check. Waiting to see if it repeats. I do have a scheduled drop off coming up and will have my indy mechanic do a thorough check. Unfortunately im not handy at all when it comes to doing work on the vehicle, I do think the indy I have is a good one and he's always been very fair so hopefully he'll diagnose further and can let me know if he notices anything.