2016 GLC300 Turbo charger failed according to dealer just after B service and car has 48K miles.! Any suggestions on why turbo would fail just after the service? Does incorrect service could cause this problem? They are saying that Turbocharger vaccum accutator failed and they have to replace whole assembly! I can't belive that just after B service this failed. They did replace all the filters and spark plugs etc.

Is it common for this kind of part to fail a day after service? I paid $1000 for service and the next day they want me to pay for Turbocharger replacement! Such a difficult situation. Please recommend what should I do.

 

Firstly, turbo failure after 48K mi is very unlikely. Not impossible but hard to imagine. As an aside, taking your car to a dealer for service is crazy expensive with very little upside. I'd strongly recommend against it if you have options..
How was the car running before you took it in? Did you have a Check Engine Light (CEL)? How is the car running after your service? Do you have a CEL?
I would take your car to a trusted independent mechanic specializing in MB (or European) cars for a second opinion. If necessary, have your car scanned for fault codes to determine what (if anything) is going on with your car.

 

The car was serviced by the authorized RBM of Alpharetta in GA and the car was running totally fine before the B service. After the B service drove car back home and check engine light with reduced acceleration same day actually. Do Mercedes dealers back their service? How come part with less than 1% failure rate could fail just after a service? Also, I received no call from the service folks after 2 days and ended up call back and that is when they told about Turbo problem. They are saying only the vacuum part is not working but they will have to replace the whole unit!

Thank you for the quick reply!

 

Do you feel it’s hard to speed up when you are driving?

 

Firstly, this is not common after a service.
I'm a technician and this is seen periodically.

Being that you just had plugs and an air filter replacement, I would first check the vacuum line going to the actuator and make sure it didn't accidentally get damage (leaking).
When the fault occurs and the check engine lamp is illuminated, it USUALLY drives normally.

Your low mileage could actually be indicative of your problem. Rubber can dry-rot from long periods of not being used and worse so if I'm a salty environment (like near the ocean).
What usually happens is the vacuum diaphragm will develop leakage and cannot control the turbocharger's waste gate as well as it should. This deviation is noted and causes the check engine lamp to illuminate, even if deviation is minute.
The problem is that Mercedes-Benz doesn't sell the vacuum actuator separately. It would be a very simple exchange process to swap out the vacuum actuator, as long as the actuator arm didn't require adjustment.
I think Mercedes-Benz doesn't sell the actuator separately, because there could be a chance of damage to the turbocharger if the waste gate was faulty. Basically, replace the entire component and avoid a client from having more issues and needing to return for more (related) work.

Sorry for the bad news, but until there an actuator available separately, it is what we have to do.

Also, servicing your vehicle at the dealer regularly should help you get 'good will' help. There are different ways they can do this. Sometimes they'll cover the labor, sometimes the parts, and sometimes everything with the client paying a portion of it (like an insurance deductible).

 

I have a 2016 GLC 300 base, got code p299 I had the turbo rebuilt and put it back in and still have the same error. I pulled it back apart and noticed oil in the Intake tube between the airbox and turbo. I assume its coming from the crack case pressure recirculation tube. I checked the diverter valve with a volt meter and it holds 9.8 oms so I know that is working. I see the vacuum actuator moving the BOV arm so I dont know where else to look. 2 questions,
1) What should I check next on under boost issue ?
2) How do I deal with the oil situation ? Could the be linked ?

Thanks everyone !!!

 

Seeing oil there is common and you are correct that it comes from the crankcase ventilation. There's an oil separator on the left side of the engine that is commonly replaced (at least in northern states) and the oil vapors are reintroduced to the intake system right before the turbocharger. Don't be alarmed of it seems excessive, this is usually the case when the vehicle isn't driven long/ hot enough. The oil vapors will condense on the cooler plastic tubing, turning it back into liquid form. That is the lowest point before entry to the turbocharger, so that's where it will accumulate.

As far as rebuilding the turbo, it may not have needed that.
You can see the vacuum actuator linkage move and most of the time it will still move smoothly. That's where people get confused about how it can still be faulty. If the rebuilders don't know the diaphragm is faulty, they may not replace it....
Even using Xentry, the actuator will almost always pass the guided test.
So, what I do and what I recommend anyone else does, is carefully remove the vacuum hose at the actuator. Then slowly apply vacuum with a manual vacuum pump. Once the linkage fully moved, maintain the vacuum applied to it (don't add any more or release any) and watch for the linkage to move back to its original position.
That is the clear indicator that the diaphragm is leaking and the source of the concern.

This is why I stated on my previous post that it's unfortunate that we can't just get the actuator separately. Would save so much time and cost.

Additionally, if the actuator does hold vacuum and the linkage doesn't move back on it's own, then you should check for leak tightness of the charged air system (leaks between the turbocharger and intake manifold-to- block connections. Can be done by smoke testing.