The responsibilities of the Certifying engineer are enshrined in law, whereas those of the engineering manager are normally only laid down by his senior managers - who are being leant on by the beancounters.
No manager would admit to the CAA/FAA/DGAC or whoever that he would pressurise a certifying engineer to let a suspect aircraft go, but in private it's a different situation.
You are entitled to be accompanied by a colleague if a manager wants to see you, so do it. If you can bring in the Quality manager, then that's even better. Like the others on this thread have stated, they can't take your ticket - but the authorities can!
When it's 3am on a rainswept ramp, it's your decision, and no-one else's. Do what is required for safe operation, and beat off the flak next day.