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Yw, I'd recommend to confirm it even though I'm 99% sure that's what it is based on the sound it's making. I've seen close to a dozen posts on fb about this problem and they all sound the same
Yw, I'd recommend to confirm it even though I'm 99% sure that's what it is based on the sound it's making. I've seen close to a dozen posts on fb about this problem and they all sound the same
I am pretty sure you are right and that is the culprit. I remembered somewhere along the lines of pressure transducer but I couldn't find the post where it was mentioned so I was doubting myself until you chimed in (thank you) and now I found it: https://mbworld.org/forums/c450-c43-...ml#post8362324
This forum member had it replaced by the dealership and problem was resolved.
I am pretty sure you are right and that is the culprit. I remembered somewhere along the lines of pressure transducer but I couldn't find the post where it was mentioned so I was doubting myself until you chimed in (thank you) and now I found it: https://mbworld.org/forums/c450-c43-...ml#post8362324
This forum member had it replaced by the dealership and problem was resolved.
oh yea that's it, that post is exactly the same sound and problem. Luckily even if someone was out of warranty it's about $120 for the part and less than one hour to replace. That part is the wastegate solenoid which is what the ECU switches on and off to regulate boost. There's a vacuum line going into it from the vacuum pump, then one line out which splits to the two turbo wastegates.
It's odd to see so many posts about this problem, and it appears that Mercedes has changed part numbers twice
oh yea that's it, that post is exactly the same sound and problem. Luckily even if someone was out of warranty it's about $120 for the part and less than one hour to replace. That part is the wastegate solenoid which is what the ECU switches on and off to regulate boost. There's a vacuum line going into it from the vacuum pump, then one line out which splits to the two turbo wastegates.
It's odd to see so many posts about this problem, and it appears that Mercedes has changed part numbers twice
Hmmm ya especially how OP in the link I linked you has a facelift 2020. My 2017 don't have this problem... yet. Maybe I might had jinxed myself lol? Thanks again for chiming in with all this detailed information and to explain how it works and the function of it I am sure others will find this information useful. Enjoy your car!
So I should make the dealer focus on the solenoid not the coolant system or do they work together ?
thx
Some that have coolant leaking around the cap area fixed this sound by replacing the coolant cap. It is because the suspected cause was air trapped in the coolant system but then it is probably not the true fix, the pressure transducer that forum member BayAreaAMG mentioned is the true fix.
Anyways, here is the thread that I was able to find again where OP there mentioned it was fixed by a coolant cap, I am seriously curious if it came back though (OP there did mention it didn't come back since for a few days but not sure if it then reappeared but thread wasn't updated after a few weeks for example): https://mbworld.org/forums/c450-c43-...ml#post8450423
My advise since you are under warranty, get the dealership to replace that transducer for a more effective and permanent fix plus like forum member BayAreaAMG mentioned, it is a cheap and easy thing to replace even if you are actually out of warranty.
Yea the leaky coolant cap is a separate but common issue on these cars. I had leaking coolant from the main reservoir, replaced the reservoir cap and corrected the coolant levels (dealership overfilled it) and never had the problem since.
I imagine the wastegate solenoid problem can be intermittent. The solenoid is just an electromagnetically controlled actuator that act as an on/off switch for the vacuum going into to the wastegate. To me it sounds like it's becoming partially open and closed at idle when it should be closed, but not sure
Last edited by BayAreaAMG; Feb 8, 2022 at 03:37 PM.
Mine was overfilled by a decent amount, left a nice stream of coolant on my garage floor a couple days later after the service. I guess that's when the cap finally gave out.
Reviving an old thread to ask if the boost control solenoid can be defective and not throw a code? I have zero boost but car drives normal minus power and boost. No check engine light. I’m suspecting this might be the issue along with a bad vacuum pump valve.
Reviving an old thread to ask if the boost control solenoid can be defective and not throw a code? I have zero boost but car drives normal minus power and boost. No check engine light. I’m suspecting this might be the issue along with a bad vacuum pump valve.
Do you hear the goose/honking sound? Bad vacuum check valve usually results in low boost but not completely no boost but still worth checking though.
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