Broken valve springs and defective valve stem seals can be replaced without removing the cylinder heads, typically requiring special tools and a compressed air source. Begin by removing the valve cover and the spark plug from the affected cylinder, or all spark plugs if replacing all valve stem seals. Turn the crankshaft until the piston is at Top Dead Center on the compression stroke, and if replacing all seals, start with cylinder number one, following the firing order. Thread an adapter into the spark plug hole and connect an air hose from a compressed air source. For SOHC engines, remove the rocker arm shafts, while for DOHC engines, remove the camshafts and lifters. Apply compressed air to the cylinder to hold the valves in place, then use a valve spring compressor to compress the spring and remove the valve keepers. After releasing the pressure, remove the spring and retainer, and take off the valve seal from the valve guide. If air pressure fails to hold the valve closed, it may indicate damage requiring cylinder head removal. To prevent the valve from falling into the combustion chamber, wrap a rubber band or tape around the top of the valve stem before releasing the air pressure. Inspect the valve stem for damage, ensuring it moves freely in the guide. Reapply air pressure to retain the valve in the closed position, lubricate the valve stem with engine oil, and install a new guide seal. Position the spring and retainer over the valve, compress the spring, and carefully place the valve keepers in the groove, using grease if necessary to hold them in place. Remove the pressure from the compressor, ensuring the keepers are seated, then disconnect the air hose and remove the adapter. Reinstall the rocker arm shafts or camshafts and lifters, followed by the spark plug(s) and wire(s), and finally the valve cover. Start the engine and check for oil leaks and unusual sounds from the valve cover area.
Posted by HyundaiPartsDeal Specialist 
