Noise from turbo wastegate actuator

[Quantumguy]

Hi guys,

I've got a C200 W205 2016. Two days ago, it started a whistling noise in the bonnet. I did some research and apparently, it could be a vacuum leak. While looking for a garage in the area to have a look, I heard a weird noise coming from the turbo wastegate actuator ONLY at very low rpms, near idle. I could not find the exact part number. I'm a DIYer, so I'm hoping you could help me with the part number. And also I'm open to hearing any suggestions you might have. Hopefully, I do not have to replace the entire turbo!

Cheers

 

[Botus]

you don't say what the new noise you don't like sounds like ? the VGT actuator on my fathers rattles about with the throttle

do you get a whistle or a whoosh and does it come as you accelerate or ? not unheard of for boost hoses to split - keep going they get worse till quite obvious

 

[Quantumguy]

you don't say what the new noise you don't like sounds like ? the VGT actuator on my fathers rattles about with the throttle

do you get a whistle or a whoosh and does it come as you accelerate or ? not unheard of for boost hoses to split - keep going they get worse till quite obvious

Thanks mate. Yes, I get an obvious whistle/whoosh when accelerating at about 1500 rpm which is getting louder. There is no sensible loss of power, no engine lights, and no errors on the dash. I've bought the actuator to replace it. I suspect that the most. Can you elaborate on boost hose splitting? I haven't heard of it.

 

[Larkone]

The rubber boost hoses split over time - splits hard to see so best found with smoke machine, though you can sometimes see oil mist around a split. If they are split it will run better when fixed.

 

[Botus]

on a turbo exhaust energy spins up an impeller in a rusty bit designed to get hot... 4 inches beside it is another aluminium bit with another impeller joined by the same shaft - the air filter feeds air into the end of the aluminium bit and that impeller builds up pressure (higher than atmospheric pressure) - this is how you get a performance improvement from a turbo

but squashing the air to make the boost pressure, makes the air really hot and there's a lot of it... so we route it usually via an inter-cooler, thus this pressurised air is inside large 2" or more diameter pipes going all over the place ... then because the engine wobbles about they have to be flexible hoses in places to allow for movement... the heat, pressure and movement wears the hoses out in the end and they can split... and all the effort in building pressure to make it go faster leaks out...

an inter-cooler is a bit like a radiator but its full of air not water - on a petrol engined car this air under max boost can hit 800C !!! when cool air is best for performance

 

[EmilysDad]

.....

an inter-cooler is a bit like a radiator but its full of air not water - ....

it is water on some cars

 

[Botus]

yep, but the bit that matters is still full or air...

 

[Quantumguy]

OK - I checked the wastegate and it's working (I could even actuate sucking the air by mouth, so its diaphragm is not torn). Interestingly, at idle, when I removed the vacuum line there was no noise and the car would run smoothly. But, when connected, the noise was back. There is also no visible oil or ash traces. Then I took the car to a turbo specialist. They said it's the turbo making the noise only when the actuator opens up, increasing the turbo speed - most likely a bearing is worn. Once its removed, we will know what's exactly going on. It's weird, as I got only ~60k on the clock! Bad oil, maybe.

 

[Botus]

they get hot and few allow them to cool whilst the oil is still circulating
if you then use cheap oils of don't change often enough, it escalates

I was reading a bit then saw on-line, the bit that matters with both impellers the shaft and the bearings is available as a unit - the housings are seldom trashed, its half the price to just slip in the middle bit... $250 us

 

[ajlsl600]

That's cartridge replacement. Sometimes even they can be a buggxx small diffs in casting and cany get cartridge into exhaust side casing all good if exact as origional. If not, reccomend get whole thing, sometimes a service exch pt?

 

[Quantumguy]

I haven't got the car back yet. But apparently the issue was a clogged DPF, that overheated the turbo by not allowing the excess gas through. I'll get to speak to my guy and see what they actually changed in the turbo. I assume the whole impeller, shaft, and bearings.