Tight turning problems 99 Expedition

When turning right or left, wheel bog down, don't turn; growling sound. Had power steering fluid checked and OK. Only happens on hard rights or lefts. What might this be? Thanks. 1999 Ford Expedition.

Could be a power steering pump. Listen under the hood while someone turns the wheels for you.

try going in gravel and turning, loose gravel, if it doesn't bog down when you turn and bogs down when you turn on dry pavement then you are stuck in 4 wheel drive other than that i don't know