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So I rented a compression tester at autozone because the one I own was giving me low reading. Upon using the tester from autozone the psi reached 205 average across all 4 cylinders. Before I was getting 135psi with my own tester. There was a slight bit of leak down like maybe 2 psi on the autozone gauge then it would hold, So I tightened the Valve core a little with my valve core tool, re did one cylinder and the result was a slow and low rise in psi (150 range). So I loosened the Valve core and reading are back to 205 range. I just don’t know what reading are correct? What should the Valve core adjustment be tight or loose? Just barely snug produces low,slow rise readings.
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If the valve core is tight it only allows so much so the gauge is not getting banged with pressure.
I would tighten it. You still getting a gauge reading. If the gauge was not reading I would say loosen
To make the pin touch.The shrader valve should be tight in the tester .It is designed to let flow one way but not the other. If the valve wasn’t there then you would see the pressure pulse up and down as you cranked the engine over. With the valve installed it holds the pressure on the gauge. As for the specifications on compression, I can look that up for you if you tell me what the year make model is. Generally 150PSI or better is good.
From the post, I was not sure if it was just trolling. 205 psi is pretty high and says it is higher with the valve loose, than tightened?
It’s a good idea before removing the spark plugs to use compressed air and blow all loose particles out of the plug well holes. Sometimes tiny particles get blown into the compression tester and can prevent the Schrader valve from closing completely.
That in turn will cause the tester to lose all or part of the pressure depending upon the size of the particle and how badly it may be caught in there.
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