Originally Posted by CMcAllister
Originally Posted by Cab_Burge
Most of the leak down meters I've seen and used call for 80 lbs., not 100 shruggy
My air compressor kicks on at 75 lbs. and shuts off at 125 lbs. so when it kicks on so I have wait until it shuts off to continue testing up
I set the pressure on every cylinder to make sure I'm getting semi accurate results, you can rock the crankshaft a couple of degrees with air pressure in the cylinders, not to many degree though tsk whistling and see a change, especially on a cold motor scope wrench grin



Yep. Single gauge tool needs to have the regulator adjusted every hole.


Two ways to do this. Set it on TDC - valves closed - and check it, or plug the hose in, bar the engine over until it hits the compression, give it an extra push and hold it steady until the gauge settles.

Seen both used by pros. One better than the other?

FAA certified A&P mechanics do it with the piston down low on the firing stroke and then use the prop to rotate the crank and piston back up to get it sealed up and read what their gauge says, not real precise but they are making the FAA happy by using that method shruggy work
I'm trying to remewmber the cutoff reading for failing the FAA guidelines, I'm thinking 70 % leakage was still flyable for another year on several cylinders(2 out of six shock) puke
I would go fly my plane for twenty + minutes before doing any engine tesing on compression, those air coll motors are really loose on the clearances shruggy

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)