have an ax to grind
US /hæv ən æks tuː ɡraɪnd/
UK /hæv ən æks tuː ɡraɪnd/

1.
tener cuentas pendientes, tener motivos ocultos
to have a private reason for doing or being involved in something, especially a selfish one
:
•
He seems to have an ax to grind with the company, always criticizing their policies.
Parece que tiene cuentas pendientes con la empresa, siempre criticando sus políticas.
•
I don't have an ax to grind; I'm just stating the facts.
No tengo motivos ocultos; solo estoy exponiendo los hechos.