EGR operation

[darrenjane]

Hi
I’m just trying to understand how the egr valve/ cooler operates and would be grateful if somebody could answer my queries. I see there is a butterfly type valve inside the egr cooler operated by vacuum - what’s the purpose of this and how does this vary from the main solenoid egr valve?

I’ve a 2011 180 on 51k miles and have recently had my original (no suffix) egr valve and cooler replaced with a D suffix after it failed. The solenoid valve was seized with soot as was the butterfly valve. I believe the butterfly was seized closed - Is this better or worse than open? I had my oil changed at the same time and am now monitoring oil usage to check if there has been any damage to the cylinders.

Thanks

 

[VW Guru]

High the purpose of the butterfly valve is to direct the flow of exhaust gas either through the whole cooler for maximum cooling effect or bypass the cooler and direct flow the gas into the engine it all depends on the engine load/temperature/rpm. As to how much flow of exhaust gas is required and how much it needs to be cooled.

 

[Volkywagen]

It doesn’t just effect these vans, we have a fleet of Volvo excavators and it effects every one of them. Some of them have had them replaced three times in 6 months. Ongoing technology I think.
I know that lots of ticking over/low revs/ low temp exhaust gas doesn’t do them any good at all

 

[darrenjane]

Thanks for the explanation - now I understand better....