imported post
Replacing valve stem seals.
I've seen adapters built from an old spark plug and a quick disconnect for an air hose. Piston moved to TDC and combustion chamber filled with air from compressor. The pressurized combustion chamber holds the valve in place while the rocker arm, keeper, spring, and seal are removed. The new seal is installed before reassembly. I suspect this same procedure will work on a wing. If I am wrong someone please correct me! Terry