I did a leak down on my car yesterday. Cylinders 1-3 were all around 5% leak. When I tested cylinder 4, the leak gauge would spike to 60% then immediately drop to around 5% and stay there. The spike and drop very quick and took less than a second.Then a couple of seconds later I heard a single click from the head. The leak gauge did not change when I heard the click. I'm pretty sure that cylinder 4 was at TDC, but I did not take the valve cover off so I'm not absolutely sure. Is this something I should worry about, or is it because I was a couple of degrees off of TDC on Cylinder 4?

Additional Engine Information:
2000 Type R with the original B18C5
83000 miles
All original/stock internals
Previous owner had a turbo installed for ~10000 miles and ran 6 lbs of boost
Oil consumption is less that .25 quarts every 3000 miles.

 

you're fine. Drive it and have fun.

 

Any idea what caused the click in the head or block?

Its very difficult not to have fun driving a Type R.

 

The motor may have turned a bit and another cylinder's valves closed.

 

im going with a valve slapped shut for whatever unknown reason

 

I thought that it might have been a closing valve, but the click happened several seconds after the leak gauge dropped to less than 5%. I figured that if a valve closed it would coincide with the leak percentage dropping. I had the valves adjusted six months prior to the leak down test and everything with the springs and rocker arms looked good. Was all this caused by not being exactly at TDC on the cylinder I was testing? Could the click have been the PCV valve closing because the cylinder was between the exhaust and intake strokes and not the compression and power strokes? Is it bad if the air pressure from the leakdown test caused a valve to slap shut?