I was checking the compression on my nailhead last weekend and after testing two cylinders, I was unable to get a reading on any of the others. While my son cranked, the gauge just fluctuated around 20-30 pounds and when he stopped, it fell to zero. When I re-tested the first two cylinders, I got the same low (20-30) pounds during cranking. I had warmed up the engine, removed all the plugs, grounded the coil wire and did it basically the same way I always do. Is a faulty gauge the only answer? Or could I have forgotten something. The little valve on the gauge moves freely and seems to be seating properly. Another question. After I checked the compression, both cylinders peaked at about 195 and slowly, the gauge continued to drop. Is this leakage from the gauge? Does this mean something was giving out on the gauge or is that normal.
Check to make sure the Gauge is operating correctly... I left the Valve out of mine once and it did the exact thing your seeing...LOL. There should be a Little Screw in valve identical to what's inside of a Tire valve stem. That could be bad or gone (like with mine).... I don't know about yours, but mine was inside the hose on the end I screwed into the cylinder. Bad gauge is the only explanation.. as if it was low compression, the pressure would hold at 30 until you hit the release on the gauge.
