sounds like you have a blown steer clutch piston seal or two,one per side..there is a hydraulic piston behind the clutch that pushes the steer clutch in to steer..the foot pedal controls the steer valve on top of the rear housing,this valve sends trans oil to each side steer piston down inside the case to steer the loader.These seals ride on a shaft that has bearings that support the cross-shaft that the ring gear and input pinion gear from the transmission.When the bearings go bad they allow play in the shaft which takes out the steer seals and allows the steer pressure to leak past the seal and back into the case.When the oil gets cold sometimes the loader will steer due to the oil viscosity being thicker and it allows some steer pressure to the clutches then.When the oil warms up then it blows past the seals and you can't steer. You have to pull the whole back end of the machine off,(ROPS/Cab,fuel tank,operator station,hyd tank,etc) remove the top covers to the rear compartment,pull clutch packs and use the Cat hyd tooling to remove the clutch piston guide to change the seals,Better to replace the bearings too while you are in there.There was an bearing upgrade for this,we discussed it elsewhere on this page,Nige supplied the dealer upgrade info-awesome!) Anyway the piston presses on the tapered ends of the crossshaft with the Cat hyd Push/Pull tool,about 20T pressure to pull it off and reseat the piston guide back onto the shaft. Get qualified help and the proper tooling(Cat push/pull tool, and a 2-5/8"socket+drive for the shaft nut) or you will be doing it again. A 15/16 ratchet box end wrench makes getting the steer clutch mounting bolts out easy once you break em loose) My machine(977K) has the same issues I havent dug into it yet.) It sounds like your machine has the same problem.
