Leak Down Test

This involves pumping high pressure air into the cylinder and noting how quickly it leaks out on a gauge. The leakage rate should be very low if the rings etc are in good condition. Most garages have leak down testers and it might be worth having this done if the compression test shows a problem but you aren't sure where it lies. During the leak down test you can also listen for where the air is escaping and this can pinpoint the problem to a valve, gasket or ring fault. If the leakdown test shows no fault but the cranking pressures are low then it must be a cam lobe or cam timing type of issue