I have a LQ4, new block, rods, pistons, and rings. I took my time and made sure everything was oriented correctly, while assembling the shortblock. I just got my head gaskets in so I put those on. I then decide to put a spark plug in each cylinder and give it a couple turns. So I turn the crank maybe a 1/4 turn when I started to feel some resistance, and then pssst!!! Air is leaking passed the rings, it scared me at first, but I figured it was because the rings haven't seated. I tried another cylinder same thing happened. I don't have a gauge so I just went by feel. Is this normal?

 

The piston rings do not create an airtight seal. At rpm the pressure does not have as much time to leak down. Normal operation

 

If the system is primed up with oil then remove the plugs and install a comp checker. Jump power to the starter and check the comp the correct way. Report back what the readings are.

 

Who knows what pre break in compression should be on his setup?

 

Any engine will have that psst sound when you turn the motor over by hand with plugs in it.

 

Combustion forces the compression ring out to seal

 

Its normal, all engines leak down about 10%.

 

Thanks for all the info.

I'll do that for sure when I get the engine back in.

 

Agreed it sounds normal, my last post was more a challenge for those say to do a test