Assuming you mean coolant (not water), you probably have a bad head gasket or a cracked head.
Yes , engine coolant can get in an engine cylinder from a bad head gasket , a warped or cracked cylinder head , a bad intake manifold gasket etc. ( P.S. I'm not a mechanic / technician )
If you are getting white or grey smoke out of the tailpipe , especially when the engine is warmed up , you have coolant getting into an engine cylinder from a bad head gasket or warped or cracked cylinder head
THE ONLY WAY TO TELL IF THE CYLINDER HEADS ARE BAD IS BY REMOVING AND INSPECTING THEM.(NO ONE IS THAT GOOD AS TO BE ABLE TO TELL WITH OUT LOOKING) THE NORMAL PROBLEMS THAT YOU GET THAT ARE CYLINDER HEAD RELATED ARE NOT ALWAYS DUE TO A BAD CYLINDER HEAD.
I'm guessing that it's engine oil you mean. It can come from a bad oil cooler if it's got one . Could also come from a bad cylinder head gasket, leaking seals on wet type cylinder sleeves, warped cylinder head or block, a crack in either the head or block. It will take some time consuming troubleshooting.
YesYes
could be a bad head gasket or cracked head.
bad head gasket , warped or cracked head
You bet it would. That's the most common reason for oil/coolant mixing. ======================================================= A bad head gasket or a warped cylinder head would be more common than a cracked cylinder head
Your head gasket or cylinder head is cracked.
Bad cylinder head gasket or valves.
Bad head gasket , warped or cracked cylinder head