2. You have a leak between the water jacket and the cylinder wall (cracked block/cylinder wall).
3. You have a leak between the cylinder head water jacket and the combustion chamber (cracked head).
Depending upon how bad the crack or leak is, a compression check may or may not indicate a low compression. But it's still worth a try. A leak in only one cylinder won't show up in an adjacent cylinder unless you have water in that cylinder, too. I don't see how bad piston rings can cause water in a cylinder.
You want to check for water in the oil to see if the leak manifested itself into the lubrication system.
Your description of the actual symptom isn't too clear. Is the water actually IN the cylinder or accumulated around the spark plug (without removing the spark plug)? If the water is actually IN the cylinder, see my 1, 2 & 3 above. If it just accumulated around the spark plug, you may have a cracked head. Look to see if you have a leaking radiator hose or heater hose that is routed near that cylinder. More troubleshooting would be needed before you consider tearing down the engine.
Hello!
Is it water for sure, or coolant? If it's water for sure, check your other cylinders, most likely the spark plug wasn't tightened down properly and allowed water to enter through the threads.
If it's coolant, check your oil, and radiator for signs of either or. Do a compression check on all the cylinders, noting the pressure of each cylinder. If the compression is low, then most likely the beginning of a head gasket issue. And also if the pressure between cylinders is +/- 14 psi difference, most likely head gasket or piston rings. Hope that helps. Good luck!
blown head gasket, or possibly a cracked cylinder
Good asking... I also need to know about this...
Could be Intake Manifold gasket on some engines. On GM V8s it would be cyl 1, 4, 5, & 8, where the waterpassage is close to the cyl.
An inexpensive *cooling system pressure test will tell you if there are any internal or external cooling system leaks.If an internal leak is found a cylinder leak down test will show exactly where the internal leak is found.
These two tests must be done before thinking of tearing the engine apart.
Cylinders rarely crack in hot weather. When an internal leak is found it's normally in the hottest part of the engine which means a head-gasket, or cracked cylinder head in the combustion chamber. If the cylinder heads have to be removed an automotive engine machine shop will test them for cracks and check them for flatness. If they're not perfectly flat they are re-machined till they're flat before replacing the head-gaskets.
That you likely have a very badly blown head gasket . . . if not, a cracked block or head.
