Homemade engine cylinder troubleshooting tool
Thread Starter
Instructor
Joined: Aug 2002
Posts: 198
Likes: 0
From: Yucaipa CA
Homemade engine cylinder troubleshooting tool
Found this on a hotrod site.
Homemade engine cylinder troubleshooting tool
From Crankshaft Coalition Wiki
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.
Homemade engine cylinder troubleshooting tool
From Crankshaft Coalition Wiki
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.
Burning Brakes
Joined: Mar 2006
Posts: 891
Likes: 18
From: Dayton Ohio
I used the pigtail of my compression gauge once to perform this test. Found a bad exhaust valve. (not on my Vette though) It is a good troubleshooting method.
The tail of most compression gauges are essentially the tool you describe.
The tail of most compression gauges are essentially the tool you describe.
