How to fit a dump valve?
Hi In a petrol turbo vehicle, when you let your foot off the gas to change gear, the throttle valve closes, and the boost pressure which has built up then needs somewhere to escape, which is where the dump valve comes in. It opens up under boost pressure, and allows the pressure to escape through it, hence the whooshing noise. However, your son has a CDTI, which is a diesel, and diesels don’t have throttle valves, thus nothing to block the boost pressure from escaping into the intake, hence a bog standard dump valve won’t work. He needs to buy a dump valve kit specifically for his car, which works off the vacuum set up on the engine, and which is nowhere near as effective as the petrol versions.
