From movie Titanic(1997), you can find a transcript here
Ismay: So you've not yet lit the last four boilers?
Smith: No, I don't see the need. We are making excellent time.
Ismay: The press knows the size of Titanic. Now I want them to marvel at her speed. We must give them something new to print! This maiden voyage of Titanic must make headlines!
Smith: Mr. Ismay, I would prefer not to push the engines until they've been properly run in.
Ismay: Of course, I'm just a passenger. I leave it to your good offices to decide what's best. But what a glorious end to your final crossing if we were to get to New York on Tuesday night and surprise them all! Make the morning papers. Retire with a bang, eh E.J.?
Ismay: [Smith nods reluctantly] Good man.
What's the meaning of run in here? From thefreedictionary, run in can be translated into two meanings:
- A quarrel or an argument.
- Printing Matter added to a text.
Of course, neither is suitable for the context. So how to explain "run in" here?