Hi

i think the head gaskets gone, well a mechanic is saying that, just want your opinion on what might you think it is.
basically the thermostat housing is leaking, was supposed to be fixed today. the car failed to start and it only did after turning the ignition a load of times. the leak is so bad that a full tank of coolant/water was gone in a day. now i can clearly see the leak but he was saying that the cylinder is flooded and is misfiring. would that be from the head gasket or the faulty thermostat housing?
hoping its not the HG seeing that it will cost way more money to fix. also there is white smoke coming from the exhaust.

if anyone has any ideas, i'd appreciate it.
Thanks