Heat, Pressure and Soot: Trouble in the Intake

Modern intake manifold modules with swirl flaps help reduce fuel consumption and emissions. At low engine speeds, closed flaps improve the mixing of air and fuel by increasing turbulence. At higher speeds, the flaps open to increase airflow through the intake system. The downside, however, is that soot particles from the exhaust gas recirculation (EGR) system can accumulate over time, clogging channels and contaminating components.

In the damage case illustrated, a defective EGR valve caused hot exhaust gases to be continuously routed back into the intake manifold. Over time, this gradually burned a hole into the manifold. Under normal conditions, the EGR valve only opens in specific engine speed ranges and load conditions, mixing exhaust gases with the intake air to lower combustion temperatures and reduce emissions. When the system is functioning correctly, modern plastic intake manifolds are designed to withstand this. Over time, however, the valve can become carbonised and may remain permanently open in the worst-case scenario. This results in a constant flow of exhaust gases into the intake system, increasing temperatures. Eventually, deposits from the EGR system can ignite in combination with oil vapours from the crankcase ventilation system inside the intake manifold.

So when the intake system finally gives in, AIC offers a wide range of intake manifolds, EGR valves, and charge air hoses with clamps. Just take a look in the online catalogue.