Join Date: Dec 2008
Location: Tyler, TX
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EGR is used to REDUCE combustion temperatures, thereby limiting the production of NOx (a pollutant).
The way it works is by mixing 0%-20% of the total intake charge as exhaust. Exhaust contains no oxygen, so it will not support combustion.
The EGR cooler reduces the temperature of that 0%-20% of the exhaust that is routed into the intake stream from approximately 600*F to 250*F by passing coolant thru the cooler.
After the exhaust leaves the EGR cooler it travels to the EGR valve, this valve meters the exact amount of exhaust that gets into the intake stream. This varies by exhaust back pressure, intake pressure (actually the pressure differential between intake and exhaust manifolds), and the amount the EGR valve is open.
By keeping the EGR valve closed, ZERO exhaust flow travels thru the EGR cooler. While the EGR cooler is physically attached to the "y" pipe, and there will be some heat transfer, it is greatly reduced because no exhaust flow moves thru the cooler with the EGR valve closed. You cannot "push" exhaust out of a welded pipe any more than you can "push" it thru a closed EGR valve. Therefore, the heat load on the EGR cooler will be dramatically less than with a fully functioning EGR system.
'93 F-250 HD, 7.3L IDI, 5spd - FARM TRUCK
I Support: Trailer brakes an every axle over the towing vehicle's GVW; CDLs for RVers; Safety inspections for ALL vehicles and 6 axle trucks (97K GVW proposal).
Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote - Benjamin Franklin
I vote for LIBERTY!