Recently aquired 97 Taurus GL power steering fluid smells burned and appears ugly brown. First time I opened the hood I noticed that the top of the power steering pump cap was full of fluid as if somone had poured fluid on top of the cap. Fluid was a little low. I suspect that there was a vapour lock in the system and the fluid burped out through the little breather hole in the cap. What is the best wa to flush the system and replace the fluid without getting another vapour lock?