why would the engine blow with no warning on a 2002 ford focus

could be a ton of things. What was the maintance like? there could of been a "weak" part, the oil pump could of got clogged. I have seen great engines go with no explaination. But it looks like you need a engine or a new car.... So to answer your question, could be many reasons. If you replace the engine, ask the mech' why the old one let go. That is normally the first thing people ask me when their engine blows, I always keep the parts to show them. Hope this helps, best of luck to you.

Agreed. I would suspect possibly a timing belt, but it could be anything from the clogged oil pump to a connecting rod that finally broke. You have 177,000 miles on a 2002 Focus? That's a LOT of heavy driving, basically 30,000+ miles per year, almost double the national average.

i also have a 2002 focus and i blew a rod at about 120000 ran great untell then it was the base like engine and now i would like to put a zetec or svt motor in it can sumone help me

I dont think it would be a timing belt. If that thing came off she would have more problems then one right now. Since the engines are interface engines that bad boy comes undone your banging pistons with valves.