How to Exhaust Through the Exhaust Valve?
2 Answers
Exhausting through the exhaust valve involves the following steps: 1. The exhaust process can be divided into two stages. The first stage occurs when the piston descends during the expansion stroke but has not yet reached the bottom dead center; the exhaust valve opens at this point. The pressure inside the cylinder is approximately 4 kg/cm² (when the carburetor throttle is fully open), which is much higher than atmospheric pressure. The exhaust gases rush out at an extremely high speed (about 400-500 m/s), creating a loud noise. 2. The second stage is the piston-driven exhaust phase, where the piston moves upward from the bottom dead center to push out the exhaust gases. After the piston passes the top dead center, the exhaust valve remains open to allow the exhaust gases to continue flowing out due to their inertia. The exhaust valve closes only after the piston has descended a certain distance (equivalent to a crankshaft rotation of 10-20 degrees), and the exhaust process stops. Therefore, the period from the start of the piston's upward movement to its completion is the piston-driven exhaust phase.
As a seasoned car repair veteran, bleeding the brake system through the bleeder valves is typically done to remove air bubbles. The steps are: first, park the car on level ground and turn off the engine; locate the bleeder valve on each wheel, loosen it with a wrench but don't remove it completely; attach a hose to the valve outlet with the other end in an empty bottle or container to collect old brake fluid; have an assistant sit in the driver's seat, start the engine (required for some systems), then instruct them to gently press the brake pedal; while the pedal is depressed, I open the valve to release air, and immediately tighten it once bubbles stop appearing; repeat this process several times until the fluid runs clear and bubble-free. After completion, check the fluid level and top up with new fluid. Safety is crucial—wear gloves and goggles to prevent fluid splashes; if the valve is rusted and hard to open, try applying some lubricant. Regular bleeding prevents spongy brakes and extends the system's lifespan.
