I have a D8N 9TC02252 that we have put about 25 hours on since buying it. Changed all fluids and cut all filters open and everything looked great. Has run like a top all along. Today the blade circuit acted up in that it will not raise the blade or lift the front of the cat when dropping the blade. It will raise and lower only until the slop is out of the pins and the load comes on the cylinders. It is acting like there is a couple hundred psi in that circuit. The blade tilt and steering both are acting fine. The issue showed up suddenly mid push; not a gradual worsening. I did a search here and found mention of the quick drop valves on the cylinders acting up. I pulled the caps on the front of the valves and the plungers and they slid smoothly in the bore and no material restricting their travel. The hoses to the cylinders do not jump when the lift circuit is activated so I don't believe there to be flow to them. Haven't checked the flow or pressure on the blade circuit as I was doing this in the dark and finally called it a day. I'm thinking the issue is in the control valve. I pulled the floorboard and verified the linkage is working. I'm printing parts diagrams to take with me tomorrow. Just wondering if the great minds at HEF had any ideas or if I'm overlooking something simple? Thanks
Check your lift cylinders. Bob
Hi Bluox. Are you meaning to see if the piston came off the rod or? Thanks.
Take the hose off the stem end of the cyl. and block the hose. Then put pressure on the other end of the cyl. ,if oil comes out of cyl. it is bad. Bob
I unhooked and checked the pressures on the lines to the blade manifold in front of the rad and only have ~300 psi on either line. It appears in the parts diagram that each valve section has its own relief valve. I'm thinking that the spring failed in the relief valve?
Or the seal rings disappeared ,pull them out and see just don't mix them up. If they are alright pull the spool. Bob
I pulled the relief valve (# 18) and the springs and seat looked good. I'll try the spool next. Which seal rings are you referring to? Thanks.
Sorry brain fart, meant seat ring. Bob
Turns out spring #28 was bent and not allowing valve #10 to open. Not sure how it bent like that? Managed to find a similar one and cut him down to length and that cured it. Will order the right one to have on hand in case he acts up again. Dad's nearly done recorking it and should be rolling today. Thanks Bluox.