hello to all… i’ve come here to ask about turbo noise on the om642 engine (Gl350.) I just want to confirm if this is normal or not… When in park, and giving it some revs, it sounds like the compressor of the turbo surging when i let off the throttle after giving it some gas… but when i do it again, it sounds like a blowoff valve… just releasing the pressure into the atmosphere, and won’t do compressor surge again… I notice the compressor surge alottt when driving low speeds and building boost for like 5 seconds, then letting off. To me, I don’t like the sound… I know it’s normal for some turbo cars, as i know why it does it, and how it works… but i bothers me sometimes because…
Questions:
1. Is the compressor surge normal on these…
2. What is the reason for it to sometimes surge, or blow off
3. And do these even have Blow Off Valves?

Ive attached a video of someone recreating the compressor surge sound when in parked. I can never get it to do it on camera. This is not my video and the credits go to wherever and whoever i got this from…

 

Hi, yeah I would check your turbo actuator. Little black box attached to turbo. It controls the waste gate which doesn't seem to be working in this video. Fairly easy fix, just replace it.
Cheers

 

Thanks for the reply. To be honest, i did think it was that, but that’s weird. I don’t think it causes damage, but i wonder… do you need to calibrate them? We had to replace the turbo and we got a junkyard turbo, good shape just had no actuator. We exchanged our actuator to the used turbo, and since then we have been hearing it wayy often

 

Sorry been busy, did not calibrate mine, don't think it's necessary or possible. I just bought a cheap one from China, works fine.

Don't think it does damage, the noise is from the air breaking the sound barrier as if forces its way backwards out around the turbine blading as it has nowhere to go IIRC.

 

Personally, I think it sounds cool. Like a rally car or something (turbo flutter)

But how would a bad wastegate cause this sound? Sounds like the excess boost isn't venting properly. I'd look in that direction.

 

Hey, looks like we are on the same boat.
I have a w211 om642 . I had a turbo faliture and i was obligated to change the turbo .

got a used one, and it made only one day this flutter noise same as yours in the video. This turbo had an other issue (air leak and hissing noise ) so i had to get an other one.

Next turbo everything went smoth for 1month then i started hearing the same noise as you . My mechanic told me that maybe it was doing a DPF regen . I went for a drive 3k rpm for 15miutes. It seems like the noise was gone. Next day i was still able to hear it , but a little less.

Then my mechanic said it may be that is the Westgate of turbo . But not sure since i heard the same noise from 2 diffeent turbos. The one the car had when i bought it wasn't doing any flutter at all


I just want to know if you have solved this issue , bc I dont like the idea of getting a 4th turbo 😅.

 

Hi. So i ended up selling the car like that. It was burning too much oil, like crazy amount of oil. I woukd fill to max and in about 900km it would drop to min and take about 4L to fill back up. I then got engine light for Regen too frequent. I checked data and it said it was regening every i think 22km, which is HORRIBLE.

I had the original turbo in the car, and it rarely made that noise, but it was quiet. It did burn a little bit of oil even in the original turbo (not sure how much but it gave us low level after 3months of lots of driving) Then the turbo completely grenaded its self while in boost, and made us replace the turbo. We bought a used one from a junk yard for a ridiculous deal, and since then it had been making that noise a lot more often and burned a lot of oil. I do think i was able to hear it a lot more because of new air filters when we changed the turbo, because i was able to hear the turbo spooling a lottt more with new air filters. the old ones were so disgusting i don’t even wanna post it here, and i think that caused something to enter the turbine and kill the original one.

But, why it’s causing this noise. This noise is called Turbo Surging. Basically when you’re off the throttle, and it closes the throttle body, the remaining boost pressure has no where to go, and thus, the air reverses into the turbine, and creating that noise. kinda like it’s chopping the air. These om642’s make about 33psi when in boost, so it’s a lot of boost pressure. although the terminology seems correct, i really don’t feel like it’s SUPPOSED to do that. i don’t think tbey have any kind of blow off valve or some kind that reliefs the pressure in the intake, because i never saw one. i had taken off the pipes from the turbo to the intake manifold because i had to clean out the intercooler when the original went kaput.

I really don’t have an answer for you other then to try eliminating the turbo actuator. i know xentry had a testing procedure for the actuator but i don’t know if it would catch that as a fault. Good luck and let me know if you figure it out!

 

Mine has made that same noise since after the AEM was performed. Been to the dealer numerous times for it and they tell me nothing is wrong. I can't find my thread/response I posted.

 

IIRC there is no throttle body on a diesel. Gas engines have throttle bodies.

 

are you sure. i saw some kind of opening and closing plate that looks exactly like a throttle body after the intercooler

 

Swirl flaps?

 

Thank you for the quick response.Much appreciated!

No its not supposed to do that noise ( The chopping air noise ) i think i will dig one more time into that , or just sell the car .

I hope that i may have a boost leak somewhere. If no boost leak its most likely the VNT ( turbo geometry) .
The funny part is that i may had bad luck with 2 Turbos having bad VNT.
A good start would be the turbo actuator even if mine seems to work fine ( testing ignition ,idle , and reving)

Regards

 

This is a video, when the choping air noise can be heard on the end of the video ( when i second rev the car ) first Rev i hear whooshing sound only . This Whoshin sound doesn't bother me . But that chopping air that is what I dont like.

 

Sorry , i didn't get what's an AEM ?

Thanks

 

Swirl flaps are inside intake manifold.

 

Yeah the whoshin is completely normal. But that’s what i don’t understand. Why would it randomly do the surging? Hard diagnosis tbh

 

An other thread suggested getting a new Garrett Turbo
which in this case i will stick with the flutter/surge sound 🤣.Since you have already sold the car i may reply in the future just for curiosity if i manage to solve it .

All the best

 

Haha thank you please let me know if you do solve this.
I obviously know it’s not normal and it started doing this after i changed for a used turbo. I obviously kept the fluttering as it does sound cool Lollll