Editing Leakdown tester homemade engine cylinder troubleshooting tool

If you have an engine cylinder that is not as strong as the rest, and you have determined that it is getting spark, here's how to make a simple tool that may aid in locating the problem.

#Take an old spark plug that fits the engine, and remove all of the porcelain and the center electrode, leaving just the outer shell.
#Braze an air fitting onto the shell.
#Turn the engine over until the piston in the suspect cylinder is at TDC on the compression stroke.
#Insert the modified plug and apply 60-80 psi air to the cylinder. Be certain not to use so much air that it turns the engine.
#With air pressure in the cylinder, listen:

*If you hear air bubbles, it may be a leaking head gasket.
*If you hear air in the exhaust, it may be a leaking exhaust valve.
*If you hear air coming up through the carb, it may be a leaking intake valve.
*If you hear a hissing noise from the oil fill tube, or the dipstick tube, it may be a piston or piston ring problem.


This simple homemade device can save a lot of time in diagnosing a problem.