I am another one of those "lurkers" of HEF for some time. I have found a wealth of information here. I have a case 850k that the blade angle will not hold. You can restore the angle at any time but soon as you let go you lose the angle. This is the case for either side. The problem started after I popped a hydraulic hose to one angle cylinder. I replaced the hose but had the problem. I rebuilt both angle cylinders and the spool for the angle cylinders on the control valve. The only visible oil seepage is at the control valve on the lift valve, not on the angle valve. The service manual says the angle cylinders can't be checked by pulling a hose off and angling the blade. They have a bypass built in. Is there any thing else in the angle circuit I need to be looking at? The 850k is a good machine, plenty of power, handles easily and has done a variety of jobs here on the farm but the angle problem drives me nuts. If any body has any ideas I would really appreciate it. Any help at all would be great.
Not sure where you seen that you cant check the angle cylinders by pulling off hose and angling the blade. That would be where I would start. There is no bypass in the cylinder that I know of. What series of machine is this? Does it have a ripper? Does the blade angle move on its own, or just drifts any direction? I have seen the valve sections get cracks in them before. You would have to remove and check the valve section with crack check.
Thanks for the reply GaryHoff. This is a 2005 850K series 2 WT. No ripper. If blade is angled, it will stay put until pressure is applied on either side angled forward. If you are pushing with equal resistance on both sides of blade, angle stays where you put it. If more pressure is applied to forward angled side of blade, it starts returning to straight. The more pressure applied the faster it returns straight. You can correct angle at any time, with hand control, and it works with plenty of pressure. As soon as you release the hand control the blade starts returning to straight again. I had read here on HEF to check cylinders, pull hose, angle blade to see if oil leaks past the piston. The Case service manual gives the same procedure (p. 8002-12) but it also gives this note: "The following procedure applies to all hydraulic cylinders except the angle cylinders. The angle cylinders are designed with a by-pass that allows leakage past the cylinder packing when the angle cylinder is extended. To check cylinder packing in the angle cylinder, disassemble the angle cylinder according to instructions in section 8006." A crack in one of the valve sections is a possibility as the control valve stays wet with hydraulic oil.
No problem. Later, I also found a where it said there was a bypass in the cylinder. Your angle cylinders need to be checked in the retracted position, as should most cylinders. There was a bulletin from case on this in regards to the angle cylinders. All the cylinders I checked, I had always done in the retracted position, as sometimes the bolt comes loose on the piston, and can re-seat itself in the extended position. Start by checking the cylinders. Maybe a seal got pinched on assembly. There was a fix as fails warranty extension on the angle cylinders for the piston bolt/washer failing, but you would have seen that when rebuilding them. The next thing is possibly the anti-cav valve is bad. I think you can switch that with the load check from the tilt section or lift section, just for testing. If you had a 4th valve section (ripper section), then you could also test using its reliefs. Since your control valve is leaking, check the tie bolts, they need to be torqued to 28-34ft/lbs.
Thanks, I will check cylinders retracted first.
I would bet money that at least one of the piston bolts came loose on one of the angle cylinders. We have seen this ALOT. Hate to be the harbinger of bad news, but usually when this happens it destroys the barrel....
I checked the cylinders. The RH cylinder has minimal seepage. The LH cylinder shot a stream as soon as the engine was cranked. I tore it down and found the piston seal (an o-ring) had 2 chips out of it. When I rebuilt the cylinders a few months back I used an aftermarket kit and the O-rings came as seals. When I tore them down for that rebuild it had O-rings in it. Don't know if it was factory or if someone else used an aftermarket kit also. Diagram on Case website and also service manual show seals. I don't know if it is common to use O-rings in place of seals. Anyway, I ordered 2 seals from Case this time and expect them in Tuesday. inthedirt, appreciate your reply and certainly appreciate your info. Maybe this time we are lucky. I haven't opened up the RH cylinder yet but it only had a small drip. Hopefully the piston bolt stayed put.
Good to hear you found it. Hope you have better luck with the Case seal kit.
GaryHoff, the problem is indeed solved. We got the cylinders back together today and the blade angle works perfect. I wouldn't have found the problem yet if not for your help. I appreciate not only your knowledge but also your willingness to share it. Thanks again.