Major water leak
 

Starting from the beginning, a few weeks back I was doing about 60-70 mph the heating stopped working and sudden lose of oil pressure. When I pulled over there was smoke everywhere and oil all over the right side of the rear engine and under the car. I had it towed home and after some research we figured out the oil air separated had fail sending oil through the engine. We have replaced the parts cleaned the oil as best we could. Changed oil filter an o-ring and filled with new oil. When topping up the water/coolant it has stated leaking from the underside of the left monifold (hope this makes sense) and is pouring out. I can't find anything online to say why hope someone can help only had it a week when it happened.
Many thanks

Additional information would be helpful. Year and model. Is it leaking water, oil or both? Is there intermix, coolant and oil? Have you checked the new oil cooler to make sure it is sealed properly? Have you done any other trouble shooting? Pictures are also very helpful.

Sorry it's a 1997 Boxster, just water leaking no oil, don't think there is a mix but haven't check but no sign of oil anywhere and the water is coming from the opposite side from where we have worked on an it immediately comes out when filling up. Haven't taken any photos but can try tomorrow just the water is coming from many areas on the rear passengers side. Someone mention it could be a cracked head but just don't think it is. Not started it yet since doing all the work either.
Many thanks
Nicola

The coolant expansion tank often cracks. Check under trunk carpet. Common failure. Also check if newest coolant cap. Should be blue.