Signs of a Cracked Cylinder Head
A noticeable loss in engine power may be the first symptom you may notice, if there is a crack in your cylinder head. A loss of compression, when air and fuel are escaping from the cylinder head, is a good indication there is something wrong. You will notice that you can't travel as fast, the engine runs slower and it may sound 'rough' or it may stop. This is because the air/fuel mixture is not contained in the combustion chamber, cause its escaped, so it can't be ignited to keep your engine running.
Low oil pressure and it is putting the oil light on, the oil is escaping from where it is supposed to be, a symptom of a blown head gasket, but also a symptom of a crack in your cylinder head. This could cause oil to spill out over the body of your engine or internally where it shouldn't be.
Depending on where your cylinder head is cracked, you may also have a coolant leak. This can cause coolant to enter inside the cylinder bore, in turn causing your engine to overheat by creating steam. In any case, the coolant will be lost and possibly causing head gasket failure.
White smoke can be seen from the exhaust if it is a large crack allowing the coolant to enter the cylinder bore and turning into a sweet smelling smoke, however, a blue smoke can be seen if it is oil leaking into the bore onto hot engine components. In rare cases, exhaust gases can escape from the engine unit.