caterpillar d6c steering clutch problems

I have a d6c serial #74a that I just bought. It had been sitting inside for several years with no use. It started right up and I roaded it home(4 miles). Steered good. Took it to a job site and pushed dirt for several hours. The steering started to get sluggish(pulled back on the steering levers and nothing would happen). I looked for oil leeks and found none. Tried it again and if I held the levers for roughly 10-15 seconds I could hear a cavitating noise and then the clutch would engage and it would steer. Parked the dozer and the next day wouldn't turn. It moves forward and reverses. Checked the pressure at the elbows of the cluches. No pressure. I seen on your sight to check the suction hose for loose connections. Have not done that yet. The dozer is a ways away so I would appreciate any other ideas I might try if that is not the problem. I also checked the clutch linkage and everything seemed o.k. Also if anybody could tell me where the transmission pressure relief valves on this machine are located so I could check them also it would be helpful.

You could check the transmission and stering cluch oil filter and the magnetic screen they could be pluged

Does this machine have an oil filter and a strainer or just a strainer.

Need to get yourself a service manual but this should get you started...

Thanks, I have one on order.