EGR question

[big_keith]

Hi all,

Not your usual egr question but how exactly do they work? i know they recirculate air which has already been burnt, therefore reducing emissions. and are they water cooled by the cooling system within the diesel enginine if so can anyone explain it preferably with pics?

i am not the most mechanically minded person

cheers all

keith

 

[Dave_88]

No they aint water cooled but couldnt tell you exactly what they do. All I no is my car runs miles better now ive ripped mine out!

 

[conkerman]

Later model cars do have liquid coooled EGR systems. My Exeo looks to have a cooled EGR system.

EGR is used to dilute the incoming air and reduce the peak combustion temperatures. This reduces NOx emissions which are the current bugbear of diesel engine manufactuers.


Conks

 

[big_keith]

Cheers for the reply, any idea how we can tell how it is water cooled? engine codes or year they introduced this?

 

[conkerman]

Have a look at the EGR system and see if there are any coolant hoses attached.

I have an Exeo with the CR motor, the EGR system definately has a coolant jacket/hoses going to it.

My 56 plate Toledo with the PD motor is not water cooled.

Conks

 

[Muttley]

Briefly: the purpose of EGR is to reduce oxygen content in the inlet charge for brief periods of high demand where the combustion temperature would otherwise go high enough to burn the nitrogen in the charge and produce nitrogen oxides, NOx. The ECU has a map to control the opening of the EGR valve: it's generally closed at low revs, opens when you put your foot down in the mid-range but closes again as you approach full chat. Exhaust gas is used as it is the only ready source of a (more-or-less) oxygen-free gas in the car.

I find the very idea repulsive, putting hot smoky exhaust back in to the inlet. Especially when combined with the oil from the crankcase breather already in the inlet charge it produces a sticky sludge that chokes the inlet manifold and gums up the EGR eventually.

NOx is reckoned to be the work of the Devil by Californian legislators, and thus the world gets saddled with heavy environmental control measures that are recognised by many as of dubious value.

 

[nikstar]

I have a mk 4 Ibiza TDi 130, it had a water cooled egr, but its gone now! Race pipe fitted, The EGR on my PD engine combined, what i think is called an antishudder valve, basically a flap thats supposed to shut when you stop the engine, but mines been fine without it!