2. With the engine warm and idling, remove the valve stem together with the hose from the boot on the cylinder head cover (see photo).
3. Plug the hole in the valve with your finger. If there is no vacuum, check the cleanliness of the hose, the hole in the manifold, or the valve itself. Replace the dirty or broken part.
4. Stop the engine and shake the valve. If no knocking is heard, replace the valve. To do this, disconnect the hose and put it on the new valve. When purchasing a valve, take into account that the new valve exactly matches the make of the car and engine (compare the new valve with the one being replaced).
5. Check the condition of the valve stem rubber boot. If any tears or hardening are found, replace the boot.
6. Insert the valve core with the hose into place.