I'm having trouble with my D4C Series 3 SN 6YL21xx. When I try to turn left, sometimes the right track will stop pulling. I've changed the cams, rollers, pins, and plungers(spools) in the valve bodies and adjusted the linkages according to the book but it's still not working right. It did work right when it was cold but when it warmed up it started doing it again. I can only think that the piston that releases the steering clutch on the right side is getting pressurized oil when it shouldn't causing it to release?
Did you check the stem and plunger springs? Seems you have some leakage from the control valve.
Yes, put new stems and o-rings in the control valves. It worked good until it warmed up, then started doing the same thing so we knew we had a leakage problem. We dug deeper today and it looks like one of the pistons that releases the steering clutch has a problem as they are not in the same position. We'll get them pulled off and see which one is right and which one is wrong. We're picking up the stuff to rebuild them tomorrow.
I don't have the right manual to look at. Does that unit use the cylinder and piston pushing the release yoke like the D3's or is it incorporated into the steering clutch itself?
Yes, like the D3. I found the problem today. The right side steering clutch pack is worn out causing the release yoke travel to bottom out against the piston which keeps the clutches slightly loose causing them to slip. We bought all new discs from Cat today. We're pulling that clutch pack tomorrow. Got everything except the flange bolts pulled this evening. I do need the minimum thickness specs on the discs and the clutch pack total minimum thickness specs.
Yes, that all makes sense. Sorry I don't have the thickness specs on that late a tractor.