The so-called discharge valve of your car is a type of valve that allows the release of the pressure of the intake system of a turbocharged engine, relieving the pressure between the turbo and the intake ducts when the engine throttle is closed. As it is a safety element for the turbo and one of the most important components of the vehicle, it is essential to guarantee its correct operation and respect the manufacturer's maintenance advice to extend its useful life.
To do this, from the Loctite blog, they detail how a discharge valve works, how many types exist and the most common faults, as well as why these may cost you the life of the vehicle.
The main function of the discharge valve is to avoid faults in the turbo or engine components due to overpressure in the system and, in addition, to give stability to the operation of the engine. When accelerating, the boost pressure increases and, when changing gear and removing the foot from the accelerator, the throttle valve of the engine closes. At that moment, the turbo continues to work due to the inertia of rotation and, therefore, continues to generate pressure. It is then when the discharge valve opens to release this pressure.
If the discharge valve does not act, the rotating blades of the turbo are subjected to a great amount of stress (being able to be damaged), the turbo gets stuck and the turbocharging pressure drops, causing the vehicle to lose momentum. When the engine is at idle, the valve is subjected to the same pressure on both sides, that is, it is not necessary to release pressure.
Depending on the opening mode, two variants of discharge valves are distinguished:
– "Push" (or push) type discharge valve. In these discharge valves, the opening is actuated by a spring. This spring, tared to a certain force, tightens the piston of the valve keeping it closed. When the pressure at the inlet overcomes the force of the spring, the valve opens to allow the exit of the compressed air. The manufacturer determines what the spring tightening torque should be according to the specific configuration required by each type of valve. Incorrect adjustment could lead to overpressure in the turbo or compressed air leaks that would imply power losses.
– "Pull" type discharge valve. In the discharge discharge valves, the opening is activated by means of a membrane instead of by springs. Unlike the "push" version, these valves have the advantage that they do not need adjustment (tare), since they adapt automatically to any pressure value. It is a more sophisticated and more expensive model than the "push" type option, which allows a more optimized and smooth operation. Pull-type discharge valves ensure maximum leak-tightness at idle and do not leak under any turbo blow pressure range.
Pay special attention
The replacement of the turbo of a vehicle is a very expensive operation, even if you opt for the installation of a rebuilt turbo. For this reason, it is essential to follow the turbo maintenance regulations recommended by the manufacturer.
Although there are many causes that can cause a fault in the turbo, without a doubt, one of those causes is the failure of the discharge valve. These are rare situations, but in push-type valves, the operation of the spring could be affected and, in "pull" type valves, the membrane could be punctured.
It is important that the driver pay attention to substantial changes in the sound of the turbo whistle and the uneven blowing of the turbo (which could cause intermittent power losses). In these situations, it is important to go to the trust workshop as soon as possible. . (tagsToTranslate) recognizes (t) fault (t) valve (t) discharge (t) car