have an axe to grind

meanings:
1. You have "an axe to grind" with someone when you are angry with that person and you plan to confront them. - иметь претензии, испытывать недовольство по поводу ч-л или к-л
2. have an ulterior (hidden) motive or interest - иметь корыстные интересы, преследовать личные интересы, иметь шкурный интерес

examples: 1. Tell your brother that I have an axe to grind with him!

"I have an axe to grind with you." Answer: "Oh no; what did I do wrong?"

The student had an axe to grind with his teacher, because he received a low mark on his presentation.

2. His interest may be sincere, but I suspect he has an ax to grind.