This weekend I put togheter a simple leakdown tester from standard air toolcomponents. The meters are interconnected by a1 mmair passage.The principle is simple; the left meter shows a reference value e.g. 100 PSI and the right meter shows the outgoing pressure.If it reads 94 PSI the leakage is 6 percent. A race engine should only have a very few percent of leakage. I normal car engine may have 5 to 10 percent and more than this showes something is wrong.



[IMG]local://upfiles/4562/5551C6FB26D446B89924513E9EC05D38.jpg[/IMG]


[IMG]local://upfiles/4562/B240681EA95349EDA0384C543033E450.jpg[/IMG]

 

Am i correct in assuming that the hose plugs into the spark plug hole ? Like a compression tester tool ?

What causes the leakage ?

 

Leakage by the piston rings, or by the valves, or through the headgasket.