penguinjohn

hi we have a 1970 mustang the power steering is intermittent the steering box has been replaced with a new flaming river one and the pump has also been replaced with new but the power steering works sometimes and not others. there are no leaks from the system and the control valve is not leaking. Any ideas? the pulley on the new pump is smaller than that of the old one. everything works fine sometimes then it just stops

kingstrider

That sounds dangerous. If no leaks I would suspect the pump or control valve is faulty. Sometimes leaks are so small they don't really show but can introduce air into the system. Also the choice of fluid is paramount, I've heard you can ruin a new pump by using the wrong fluid.

penguinjohn

many thanks i have the correct fluid in and there are no leaks just can't get to the bottom of it everything works fine then it just stops working