I do not have an air compressor and have been wondering if i can just use my compression tester to do a leak down test? If so, then how??? If not, then why?

 

Anybody???

 

No, compression testing is one thing and leakdown is another. In compression testing, you are trying to see how much compression a cylinder has with respect to another and a known figure. Compression testing will tell you nothing as far as whether it is leaking out of the valves or rings or gasket. It will tell you that there is low cylinder pressure and that will be that. It will tell you that this one is more than 20% off the others but where it leaks, nobody knows.

You need to have valves closed and air pressured into the cylinder to tell if it is leaking from the valves, gasket or rings. There will always be a leak. Below a certain value is acceptable and above that you have problems.