Originally Posted by Bashby
Why go past tdc? Both valves should be closed, right? I've used a leakdown tester once, but couldnt justify buying one. I take the schraeder valve out of my compression gauge and hook the quick coupler directly to shop air at TDC. I have an adapter since the coupler on the compression tester is different than the one I use for my air tools. I have used a rubber tipped blow gun before when I didnt have the adapter available. I cant figure peercentage of leakdown, but I can tell where the leak is and how bad by how much air is flowing.
Hey, that works! I've used the ol' blowgun trick many times! Either way, ya gotta get past the point where the ACR is holding one of the valves open.
Usually you have to bring the piston PAST top dead center by about a quarter inch or so. On OHV units, you can check the rockers for play and go with that.