How to tell if you have a cracked head
To check for a cracked head, it would have to come off of the engine and manga-fluxed to show up a crack. More than likely you have a bad head gasket. Does the oil rise on the dip-stick? That would be a good indication of oil leaking into the oil. Milky looking oil is cause by moister, which the PCV Valve and breather element could cause if they are plugged. The crankcase needs proper ventilation.
...coolant leaking into the oil.
99 tahoe, if it's a 5.7 there is a chance it's just your intake gasket. If it's a 5.3 or 4.8 then your going to be looking at a head gasket/ cracked head for sure.
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