GMC 3911068 Valve Spring

To replace broken valve springs and defective Valve Stem Oil Seals without removing the cylinder head, special tools and a compressed air source are typically required. Start by taking off rocker arm cover on damaged cylinder head or, if we're changing all Valve Stem Oil Seals, take both covers away. Pull the spark plug out of the affected cylinder or remove every one of them when replacing all the seals. Make sure that the piston in the damaged cylinder is at top dead center on the compression stroke, beginning with number 1 if all seals are being replaced, and follow firing order sequence. Screw an adapter into the spark plug hole and connect it to a source of compressed air so as to keep valves closed during spring removal process from above. In case there is no compressed air, use nylon rope which is long enough so that it can fill combustion chamber through spark plug hole thereby avoiding drop valve. Afterwards, secure shop rags to above and below valves' cylinder head holes to prevent any ingress of part or tool. Use a valve spring compressor to compress the spring/damper assembly and remove keepers. Then check whether there is any damage on the valve stem and ensure it moves freely in its guide. Inspect for wear on rocker arm studs which may need machining shop replacements or threaded replacements on certain engines. Restore air pressure with respect to keeping the valve closed position; remove tape/rubber band from valve stem lubricate engine oil onto valve stem before installing new oil seal. Finally reassemble components including rocker arms, pushrods, spark plugs and rocker arm covers then start engine checking for oil leaks/abnormal noises at rocker arm cover area.