leakdown tests

[christians]

what is an acceptable amount of leakage for a 80 thousdand miles flat six. and how much difference between cylinders is normal?

cheers s

[sportsandclassic]

hi

i would be looking for no more than 20% leakage on cylinders and a maximum of 10% difference between cylinders.

thats only my own preference...normally more than 30% leakage and youve got some issues to deal with.

[GreenV8S]

Should normally be around 5% for a healthy production engine, anything over 10% indicates a significant problem.

Edited to add: but the expected value does depend on the size of the restrictor in the leakdown tester versus the cylinder capacity. The figure of 5% is about right for a 1mm restriction with a 500cc cylinder.

>> Edited by GreenV8S on Sunday 19th February 20:05

[Henry-F]

Be very careful on this one. There is a massive variation in the way cylinder leakage is quantified. 2 of the specialists we use give their figures in a way thats differs wildly, one of them for instance uses a figure of around 15-25% as acceptable or "normal" so be carefull you don`t start comparing absolute numbers unless they were tested by the same garage.

Henry