low compression on cylinder no. 2!

[fame_s13]

hey guys....i was thinking about going ka-t using small t25 setup with smic.
but before i did so..i wanted to do compression test.
here are the results.
Cylinder No. 1 : 180 PSI
Cylinder No. 2 : 130 PSI
Cylinder No. 3 : 180 PSI
Cylinder No. 4 : 180 PSI

so the results were not expected..i was getting 180 on 3 cylinders but one was 130psi.
then i droped about 3 droplets of engine oil and retested it but again it was at 130 psi. So im a bit confused why i have low compression in just one cylinder. so i don't know if its the piston rings, seals? etc
overall the ka runs strong..no strange noises or any issues.
any ideas? thankss
also EGR is disabled/deleted

[Razi]

If it's still 130 psi after you dropped some oil in the cylinder, it's probably your valve seals.

[martins_240sx]

yes to reconfirm. that would suggest either a cracked head (doubtful) or one or more of the valves arent properlly seating

[kouki munster]

3 drops of oil isn't going to do anything but get the top of the piston wet, fill the cap of the oil bottle and dump it in the cylinder with low compression, then repeat the test.

[fame_s13]

^ o really? ok i c... i will try doing that tomorow and c if that increases the compression.
thanks

[Gabes13]

Probably a bent valve.

[OutToWinPAHC]

3 drops of oil isn't going to do anything but get the top of the piston wet, fill the cap of the oil bottle and dump it in the cylinder with low compression, then repeat the test.

This. If not could be head gasket, valve seal, or valve stem seals...... Any blow by?

[martins_240sx]

i can see the headgasket but can you explain to me how a valve stem seal would cause low numbers? I only ask because the valve should be closed creating a seal at the valve seat. and blow by is usaully caused by piston rings crapping out from my understanding. Im honestly running this through my head and would love to hear your insight

[OutToWinPAHC]

The back of the valves can wear down, or carbon can build on them which can cause them not to always seal. With good maintenance it's usually not an issue. Chances are it's rings.

[martins_240sx]

ok i see now. when i was running it through my head i was imagining clean parts. which adds to my could be list
could be the valve guides worn allowing the valve to wiggle and not seat.