There is a project team of about dozen of people. Whole development stuff is done by a team (7 people) led by a manager who is responsible for this part of the project. The manager organizes tasks, share the workload among developers, verify quality of their work, etc.
The problem is he doesn't raise any project issues, e.g. even when he believes deadlines are too tight for his team he doesn't communicate it and just get people working until someone else realizes that there will be slip. No matter whether the problem is solvable or whether anyone else is aware of it he doesn't let PM (or others) know until it's too late.
Simple solutions, like explicitly asking him to communicate about problems or trying to get him involved in risk management doesn't work. The manager himself and his team can't be replaced with another group.
How to improve the way he communicates project-related issues?