That is great. If you have no compression on this cylinder then it has clearly failed. I attached a guide of the reasons for low compression.
I would do two things from here. First, run a cylinder leakage test. This will tell you if it is a valve and which one, or if it is a head gasket, or piston rings.
The way to do this is to put air pressure in the engine with it on TDC on the compression stroke. This way, the cylinder is supposed to be sealed to build compression and if you apply air pressure you will have air escaping the source of your issue. Either the intake (intake valve), exhaust (exhaust valve), valve cover or oil fill location (piston rings), or lastly the coolant reservoir (head gasket). I would not put full air pressure to the chamber because you could close a valve if it is too high. All you need is about 15-20 PSI. If you don't hear air anywhere, then increase it 5 -10 PSI until you hear air escaping one of these places.
Second thing is to put a borescope down the spark plug hole to see if you can see any damage. If it is not making noise when it is running then you may not see anything.
Depending on where you hear air coming out, it will dictate what your next step is in repairing the vehicle.
Let me know what you find and we can go from there. Thanks
Wednesday, June 5th, 2019 AT 3:31 PM