THE CAUSE
The good news is that 90% of blown head gaskets are preventable. The bad news is, if you are reading this you probably already have one.
They are usually caused by an engine overheating. When the cylinder head gets too hot it warps. When this happens, it can’t hold even pressure on the head gasket and the combustion pressure, combined with the extra heat blows a hole in the gasket. This can be a time consuming and expensive job, but it is very important to get it right the first time!
THE SOLUTION
In any case, the first thing we need to find out is WHY did the head gasket blow? Most times we will find a cause of overheating. Maybe a coolant leak, maybe a faulty cooling fan or blocked radiator, maybe a stuck thermostat. Whatever it is, the WHY is always the first question.
Once we know why, we need to figure out how much damage has been done. Unfortunately, the only way to do this is to remove the cylinder head and have it tested. This can take anywhere from 2-3 hours on a simple 4 cylinder car, up to a day or more for something more complicated. We get it tested for hardness, straightness, cracks and leaks. We check out the block condition, cylinder bores and pistons.
At this point we can usually give you an accurate quote for the repairs. Each engine is different. Some are quite hardy and just need a quick machining of the head and it all goes back together with new bolts and gaskets. Some heads can crack from the heat, which then require a completely new cylinder head. This is also a great time to look at replacing things like your timing belt/chain, water pump and thermostat to ensure reliability in the future.