Q: What tools and compressed air source are needed to replace broken valve springs or defective valve stem seals without removing the cylinder heads on Lincoln Mark VII Overhead valve (OHV)engines?
A: To replace broken valve springs or defective valve stem seals without removing the cylinder heads, specific tools and compressed air are needed. Remove valve cover(s) and spark plug(s) from affected cylinder. Ensure piston is at Top Dead Center on compression stroke. Thread adapter into spark plug hole and connect air hose from compressed air source. If no air pressure, insert nylon rope into combustion chamber to prevent valve drop. Remove Rocker Arm, fulcrum, and Pushrod for affected valve. Apply compressed air to hold valves in place. Alternatively, with rope, stuff rags into cylinder head holes, use valve spring compressor to compress spring, remove keepers, and disassemble valve components. Inspect valve stem for damage, lubricate it, and install new valve guide seal. Reassemble valve components, release air pressure or rotate crankshaft, and reinstall rocker arm(s), pushrod(s), spark plug(s), and valve cover(s). Start and run engine, check for oil leaks and unusual sounds from valve cover area.
Q: What are the methods available to replace broken valve springs or defective valve stem seals without removing the cylinder heads on Lincoln Mark VII Overhead cam (OHC) engine?
A: If the broken valve spring or defective valve stem seals are to be replaced without removing the Cylinder Heads, there are two methods that can be used. In both methods of repair, compressed air is usually required but if it is not obtainable, a length of nylon rope serves as a tool to keep valves from falling into the cylinder during operation. After removing the valve cover and positioning the cylinders at TDC, compressed air or rope is utilized to maintain the valve position. In this case, special tools compress the spring by using air hence allowing for the removal of the camshaft roller follower, keepers, spring retainer, and valve spring respectively. Valve stem seals are then fitted while components are reinstalled in reverse order. Alternatively, the camshaft and roller follower may be removed using a locally available valve spring compressor after which removal/installation follows a similar sequence.