1989 BMW 750 il

Low compression, misfire, water out the exhaust pipe (or steam) - do not confuse with early morning cold starts. Water being pumped out the rad overflow, milky looking oil (increase in oil level if you haven't put any in (re milky looking oil), Super clean spark plugs (if blow in the water jacket area).

Come on guys there must be at least another 20 signs

Sir Hugh of Bognor

Oil in the water, characteristic gas escape sound from leaking area (similar to exhaust blow), mayonaise around oil filler cap, reduced power, excessive water and / oil cosumption.

As this is a V12, very different exhaust sound and colour on each side.