Dear NT:

You wrote:
> Are these sentences correct:
> 1-These are the tools to repair the car.
>
This makes sense and would work. You would be more precise to say “to repair the car with” or “with which to repair the car.”

> 2-I lost the tools to repair the car.
> meaning: the tools which were to be used to repair the car.
>
This makes sense colloquially, but the way you wrote your “translation” (“the tools used to repair the car”) is clearer.

> 3-Somebody stole the tools to repair the car.
> meaning: the tools which were to be used to repair the car.
> This sentence, I think, would primarily mean that he stole the tools IN
> ORDER TO repair the car. I wanted to see if it could work for the other
> meaning, ie. “He stole the tools with which we could repair the car.”
> In this case the “to clause” would postmodify the noun “tools” and won’t
> be a purpose clause.
>
You are correct. This would normally be understood to mean, “in order to repair the car.” For the other meaning we would probably simply say, “Somebody stole the car repair tools.”