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15
Exhaust-gas recirculation cooler
A lower combustion temperature is required to reduce nitrogen oxide (NOx) emissions. This was achieved by
using a variable, water-cooled exhaust gas recirculation cooler.
The exhaust gas recirculation cooler has a bypass valve, which is opened when the engine is cold. This allows
the recycled exhaust gases to bypass the cooler and reach the intake end of the engine uncooled. As a result,
the catalytic converter reaches its operating temperature more quickly. The valve is closed when the engine
temperature exceeds 35°C, and the exhaust gases flow via the cooler.
The bypass valve is controlled by a solenoid valve via a vacuum box, whereby the valve is closed when the
solenoid is de-energised and the exhaust gases flow via the cooler.
343_017
Exhaust ducting when the engine is cold
Exhaust gas flow
Coolant
Vacuum box
Coolant outlet
Exhaust ducting when the engine is hot
Exhaust manifold connection
Coolant inlet
Exhaust gas flow
Coolant
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