expect

[Heidi]

Dear teachers,

- I don't expect him to stay so long.

Does this sentence mean that I think that he will not stay so long?

Thank you!

[SirGod]

* Not a teacher

You could say either

I don't expect him to stay too long. - This means that you think he will not stay too long. This one is what you want. (future)

or

I didn't expect him to stay so long. - Use this if he stayed too long. (past)

[Heidi]

* Not a teacher

You could say either

I don't expect him to stay too long. - This means that you think he will not stay too long. This one is what you want. (future)

I don't quite get it. 'You think he will not stay too long' and 'you don't want him to stay too long', can both meaning be included in one sentence?

- I don't expect to see you before Monday.

Does this sentence imply that I don't want to see you before Monday?

Thank you!

[Raymott]

Dear teachers,

- I don't expect him to stay so long.

Does this sentence mean that I think that he will not stay so long?

Thank you!

Yes it does.
But it would be more common to say, "I don't expect him to stay long", unless you have put 'so' there for a reason.