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om605 vacuum hiss?
veg124 Offline

Posts: 8
Joined: Jan 2018
Location: scotland
om605 vacuum hiss?

I am still learning about the new to me om605 powered W202 C250. I'm curious what is causing a back up of vacuum pressure, that's the only way I can describe it. When I turn off the engine, it slowly releases but I can totally release it if I pull a vacuum line. 

Hopefully the link to this short video of it will post here. Not 100% sure about the forum rules linking to YouTube.

I am not sure how this has, or whether it has been, affecting performance. I have blocked the EGR line with a 5.5mm metal bit but otherwise the setup is stock AFAIK.

1982 240D US
1982 300TD US
1983 300SD US
1986 300SDL US
1992 300TD UK
1999 C250 TD UK
04-04-2019, 05:09 AM
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dieseltorque Offline

Posts: 4
Joined: Feb 2017
Location: latvia
RE: om605 vacuum hiss?
Hi,, I had same noise when my c250 was stock,, it comes from turbo actuator control valve. Car was running fine without any issues.
04-05-2019, 12:26 PM
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AlanMcR Offline
mind - blown

Posts: 296
Joined: May 2009
Location: USA
RE: om605 vacuum hiss?
"They all do that"
It is the noise of the vacuum slowly bleeding out through the variable vacuum valve(s). There is one for the turbo and another for the EGR. Be happy you hear this sound. If you don't, it means that you have a larger leak somewhere else.
Now, about the bird noises that I heard ...
04-05-2019, 06:04 PM
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