No compression in on of the piston

[jworks]

Hey zilvians, need some assistance. I got a friend with a KA24E, says piston #4 has 0 compression after doing a compression check. The motor can turn on but its only firing on 3 cylinders and smoke is coming from the area around piston #4. Can anyone give me a general idea of what is possibly going wrong? Thanks in advance!

[eklips3]

no compression means dead cylinder.

time for new motor

[jacobs13]

its the ring

[psychos13]

Do leakdown test and it's most likely a fried ring

[jvgos13]

u could try to do a wet compression test by squirting a couple of drops of oil in the cylinder and test for compression again, if it holds then it confirms that its the piston ring,(DONT put more than 3 squirts). smoke is the oil burning.