I'm working on a Hyster H155xl S#F6A4128L. My engine is filling up with hydraulic fluid in about 1 week. It has a Perkins Diesel. Hyd. pump is run off drive shaft. The only thing connecting the engine to hydraulic system is the power steering pump. I put a new pump in about four weeks ago. After 2 weeks cust called and said it was same problem. I checked and eng. was overfull again. We figured we got a defective pump and put another new pump in. Out of curiosity I went and checked today.....overfull again. Any thoughts on what it could be???