On my Thomas Pro Tough 1700 skid steer the loader arms will go up, but not down. The cable from the foot pedal is operational. I then checked the solenoid that locks out the spool and it works. I re-greased the detent assembly thinking it was hanging up. Nothing worked so I took the spool out of the valve body. I had to pry it up with a board to get it unstuck. It seems like hydraulic pressure was keeping it frozen. I took it out expecting it to be galled or damaged, but it looks like new with no scratches or burrs. I ran a strong magnet up and down the bore of the valve body and there is no metal in it. I reassembled it and it moves freely up and down with the machine off. The o-rings on either end are in good shape. The neutral return spring assembly is working fine. Before starting the machine I could move the spool up and down, and could also get the float detent to catch. After starting the machine I lifted the loader up and then pushed the control down. It will not lower and the spool will only move to the neutral and up position. Again I had to pry it with a lever to get it to lower. What am I missing? Does this type of spool have to be timed with the valve body? Notice in the pictures there are a series of drilled holes and notches. I did rotate the spool in several positions to see it the would work and it did not. The manual does no mention anything about timing the spool. I have no idea what to check next. Steve
Is this an electric solenoid, I'm not familiar with your machine? it might be the solenoid is weak on the down side. Might have to check resistance, with ohm meter. also may be something freakishly different, like a deteriorating hose in the down pressure side, causing a flap of rubber to close off flow, on the down stroke. also might be bent cyl rod, too...
Thus is a year 2000 machine. It is all manual controls with a cable to the foot pedals. While trouble-shooting I'm pulling and pushing directly on the yoke on the end of the spool. The solenoid lock is tied to the seat presence switch and the belt buckle. I currently have this removed from the valve. The bucket tilt and auxiliary circuits work ok. Steve
Is it possible to switch the hoses around at either the cylinder or the valve block to reverse the up/down pressure lines?
Is the cable stretched, or out of adjustment?
X2 That would give you a good indication if you have a problem in the circuit or cylinders as opposed to the valve itself
Im gonna bet this has a pilot operated load holding check valve and that its part of your troubles.
Mike, I have definitely isolated it to the spool. Currently all the hardware(springs, detent, locking solenoid) is off the spool. When there is no hydraulic pressure I can move the spool by hand up and down in the valve body. It does not hang up. If I lower the bucket first that direction works. After I raise the bucket and then try to lower it the spool won't move in that direction. With the machine off I can manually stroke the spool to the up position then to the neutral position, but it will not budge in the other direction. The manual says it's a "series type" control valve. Oil is ported from one spool to the other to allow simultaneous functions. It has "load check valves" between the ports of each spool circuit. The function of the load check valve is to hold the boom or bucket in position during spool movement. Could this mechanism cause a hydraulic lock, freezing the spool in one direction? Steve
No, load check is there to support boom + or - until you have sufficient pressure in circuit to keep it from dropping like a rock when you shift spool. All that said. You've not truly isolated anything except to prove you have trapped oil in the spool/valve . How are you lowering the implement when it is "stuck" in the air?
I have to lever it up with wood board. Hand pushing won't release it.
When you had that school out and observe though small orifices bit between the lands were you able to blow through them
Yes. I ran a wire threw each hole and out the other side and blew it out with compressed air. Also I did not notice any nicks or burrs on the spool. Looked in great shape.
My next action would be to flip A& B change your plus sides to the negative side and vice versa that would eliminate the possibility of having a flapper in your line
So flip the two hoses on the valve body so up is down and vise versa?
Yep
How are things?
Unfortunately, I won't have time until Tuesday or Wednesday to work on it. I did find out the valve is made by Walvoil in Italy. It's considered a mono block valve. Steve
A pilot operated check valve is just that. A one way diode that can return to two way traffic if pilot pressure unseats the check ball or poppet. Say port A extends the boom cylinder. When you push fluid up into cylinder from port A it will unseat the check (they can be in the valve, inline or in the cylinder) and extend the ram. then fluid is blocked from returning back down port A until pressure from port B has unseated the check and allows oil to be forced back to valve and the cylinder to collapse. If the check is rusted shut or the orifice that supplies pilot pressure is blocked by trash or a bulged/torn seal or something youll get trouble. A flapper is a piece of delaminated hose inside an otherwise good enough looking hose. They form their own accidental check valves and trying the port swap is a great idea. You can chase lot of tail over those.
I unhooked the hoses to swap them around as suggested. One was too short to reach. But then I though that since all of the pressure was released in the system the spool should be free to travel. Again it was stuck in one direction only. I took it apart like the last time, but it was much tighter getting it out of the valve body. When it came out I was sick to my stomach. The spool is full of magnetic debris. After looking at it closely the best I can figure out is it is steel wire around .005-.006 inches in diameter. The longest piece is around .125". I have no idea where it came from! The inside of a hydraulic hose? Part of my pre-filter(suction screen) in the hydraulic tank? I can't remember if the pre-filter is wire mesh or not. I'm not sure if the pump chewed a longer wire into smaller pieces or not. Very frustrating to not know the source. I'm at a loss as to what the source is. It's not vandalism since I'm the original owner and do all of my own maintenance. No one has access to the machine as tanks are locked up. Last summer I did extensive maintenance on the entire machine. I flushed out the entire hydraulic system(drained cylinders, oil cooler, shot auxiliary hydraulics into a bucket) with fresh oil, cleaned out the reservoir(removed access panel) then flushed it out with solvent. I ran a magnet in the tank to pick up some steel flakes(welding splatter) that was there from day one. Replaced all filters, etc. I'm like hospital clean about my work. Everything gets covered(duct tape, rags, steel caps for hoses, etc). When I put fresh oil in I use a pump with a 5 micron filter. Oil never goes into the machine unfiltered. I highly doubt I introduced this debris into the machine. I did not use a wire wheel or brush. My wire brush has a much thicker bristle(.012" diameter). How do I fix it? Where do I start? All I know is it's going to be a massive undertaking... Steve .
Since the oil is common, why not start with the neighboring spool. Pull your tilt out. If there is no material, i would pull the rods out of the lift cylinders. Make sure they are straight. Check pistons for shedding material. Being unfamiliar with your specific machine, i would also remove the return oil filter. See what kinda junk you see there. Lets hope this is still a localized problem. Cuz that spool didn't look like that the other day.
Funwithfuel, The next spool is the auxiliary circuit, then the tilt. So there is a good chance it went down stream to the lift cylinders? Being a machinist I am confident this material is wire and not galled material or chips. I looked at it with a powerful tool grinding magnifier. Should I still take the cylinders apart? Should I take the valve off and go threw it at this point? The only good news is the closed loop hydrostatic system is protected by the main filter. I will cut the filter open as you suggested. Steve
I think youre gonna need to see the charge pump innards. If the pump has an aluminum body it may have been eaten pretty good. Excellent news that its magnetic, atleast thats one benefit in your favor. You can tape magnets to the easiest collection sites like filter, hose ends, dangling into tank on a string etc. Im thinking you have a gear charge pump, not a vane? Could this solvent have delaminated a hose? I would look close at the section hose feeding the charge pump. Maybe it had a loose braid get sucked into the pump or something crazy. Otherwise id think wire mesh from a suction screen. Cant think of much else. Definitely a bummer
Mike, I only rinsed out the steel tank. The solvent did not go into the system. Yes it's a gear pump with an aluminum body.
Your Only concern up to this point was lift cylinders getting stuck in the air I would start there I would disassemble the cylinders I would remove the hoses and completely inspect everything in that circuit before moving forward. I am a little old fashioned in that i try to find point of origination from point of discovery. I move out from there upstream towards pump. We dont yet know where its coming from. We do know we have presence in valve at lift/lower spool. You could remove the remaining valve assembly and remove each spool carefully to see if material has found its way into adjoining circuits. Of course it may be present at "P" and "T" but you're gonna want to know if it is in A&B of your tilt and aux circuits.
It's looking like the wire is from the pre-filter. The vendor said it is made of wire. Sometime this week I'll drain the tank and pull the filter to inspect. Does the vendor have any liability if the filter came apart?
Depends how good your lawyer is. Everyones liable for everything these days. Id think filter manufacturer, not retailer. Cut the main filter pleat, look for aluminum. If theres a bunch its probably the pump sideplates.
The source of the mystery wire continues. I got the valve off of the machine, but not disassembled. I cut open the main hydraulic filter and it was spotless except for one small piece of wire(circled in red). I did not find any aluminum from the pump. The suction filter had a minimal amount of debris, but no wire. I don't think the wire could pass through it either. Also, the suction filter is not the source of the wire because the wire is stainless steel and non-magnetic. I looked at some more pieces of the wire and I was able to unravel one section and it is probably closer to one inch long. My guess is these strands were much longer to begin with and got pulverized going through the system. My plan is to completely break down the mono block valve and inspect it for more wire and see if the bores are damaged. Is hydraulic hose wire braiding magnetic and around 5-6 thousandths of an inch in diameter? My hoses are all original and about 18 years old. Some are starting to show signs of cracking, but overall they seem in good shape. There are no bulges on the hoses and no leaks on this machine. Now what should be my next tasks? Do I need to take apart all of the cylinders? What about the hydraulic pump? I'm concerned since I don't know the source of the wire that if I don't go completely through the hydraulic system that it could happen again. The wire is so sharp that I'm also concerned it could get embedded in the lining of a hydraulic hose and then dislodge and cause havoc at a later date. Thanks for the advise, Steve
Im confused, are you still thinking this was from a "pre-filter" or no? Can you find the item that disintegrated? Sounds like sump screen or steel wool maybe.
Mike, The pre-filter is stainless steel and not magnetic so it's not the cause. I don't know the source. I didn't use steel wool and it's too stiff to be steel wool. I was wondering if it could be the steel reinforcement of a hydraulic hose? At this point I'm clueless as to where it came from. I would find it hard to believe it's been in the system since day one and just now became dislodged.
Any chance of sabotage? Crazy ex.. Grandkid playing hide the screen in the hole?
That there is none in the main filter suggests that the valve caught it
I think I would take funwithfuel's recommendation and start with the lift cylinders and hoses.
I have seen crud get left in hoses when we had some built.... usually rubber and tiny bits of abrasive/steel wire. most hose shops I've been at only appear to blow the finished hose out whith osha air so unless the crud is very loose inside it may stay stuck. Like others have said though I think it would be a good idea to work backward from the block and try to find more.
I don't think it's sabotage. No kids around and I'm the only user. The diesel and hydraulic oil caps are kept locked. There is one hose from the pump to the valve. I will inspect it. I do remember months ago when I was wrapping this particular hose with masking paper(painted the machine) I cut my finger on a strand of wire protruding out on the surface of the hose. I thought then it was weird because the hose did not appear damaged.
Hydraulic hose wire is magnetic, and an antique 1/2" hose, and slightly newer one, both measured 0.010" but they could vary for a newer hose, or a 3/8" hose. I'd sure start with that hose that poked you. For a skid steer, I think I'd run it if you find the wire came from the hose.
I doubt that makin a hose would make that kinda shaving, the cutter wheel they use is a smooth one, not like an abrasive one. Sides, I would think that any debris from cuttin, would likely show some evidence of heating. I'm still thinkin deterioratin hose. I'd look at any with wire showin, or a sharp bend. Might also be a case of contamination, from an attachment that came in in the aux lines...
I make hydraulic hoses. I cut with abrasive chop saw and there are never shards. The ends are always gonna show some purple, but never jar pieces loose. Maybe some rubber fluff but not wire. What im seeing is loose wire that got sheared by hardened pump gears like a wood chipper. Question is where that strand get in from.
Anybody consider that maybe the piston/nut is backing off the rod and perhaps starting to shed material. I'd have pulled the lift rods out by now, worse case scenario, you need a cylinder, best case you repack yours.
He says it's a long piece of wire, he looked at it closer than I have, and he says it's not swarf. It could come from a cylinder, but given what he's said, I say the hose is the most likely place, especially considering a hose stuck him already. Not original cutting debris, but the hose got twisted/torqued/whatever.
Agreed, but i would think the wire core of the hose would have held up longer than the vinyl/rubber inside jacket would have shown up in the filter. There should have been evidence is all I'm saying. The man has been diligent in his work. He's already ruled out suction strainer, there really is no pilot circuits as it's cable/linkage controlled. I have my way of doing things, just like everyone else. Not knockin anybody. I just get tunnel vision from time to time
MYSTERY SOLVED! The source of the wire that has contaminated my entire system(hydraulic and hydrostatic) is a brand new NAPA hydraulic filter part #1494. I fished out a longer wire in the control valve that still has the coating on the wire(look at picture). The single strand on the left is out of my valve. The small patch is a piece I cut off of the filter. I'm beyond pissed that the filter that was supposed to protect my hydraulic system has done extensive damage to it. This is going to be a huge undertaking to rid my system of the filter wire. I'm also pretty sure the wire damaged the bore to my valve. I really need some guidance as to how I should proceed. Immediately after this filter is a "T". One hose goes to the gear pump and the lift system and the other hose goes to the two hydrostatic motors and then on to the geroler motors. This a closed loop system that gets a small supply of oil to replace the case drain leakage. Do I have any recourse with NAPA? Steve
Wow. Looks like their "welded" wire mesh has a plastic/paint on it that does as much to hold the mesh together as the "welds". There's usually loose wires at the cut ends also, from the shear knocking the welds loose. I think I'd carefully take that filter apart and see if you can find where the wires came from and if it was one, two or several wires that were likely missing. Definitely take apart the hoses and inspect, maybe there's a screen at the inlet to the hydro's. You can certainly try to get recourse from NAPA, they might realize $$ to compensate your damage is better than the bad press and more cases of damage being recognized from the story. On the other hand, in court you have to pay "experts" to prove your damage and you won't come out ahead. And if Napa paid everybody that claimed a napa filter killed their engine, then they'd be bankrupt the first day.
I'm not an engineer or mechanic by trade, but do you think if the wire went into the hydrostatic side it would have damaged it already? It seems OK. The "T" right out of the filter goes straight across to a check valve then to a bigger hose to feed the oil cooler, then the reservoir. The other end of the "T" points straight down and goes to a smaller hose that replenishes the case drain. What are the odds that the velocity and the main flow of hydraulic oil carried the wire pieces across to the loader hydraulics instead of down to the closed loop hydrostatic system? Obviously the hydrostatic system is the most expensive to repair. Do I need to just take it all apart also? I don't see any other screens in the parts manual unfortunately. What would be an estimate of costs for a repair shop to do this big of a job? Basically to go through the entire system and hunt down all of this wire? I need to have some talking points when I speak to the manager at NAPA. Steve
Glad you found it. Sorry it was supposed to prevent this sort of thing. Most hydrostat systems are closed loop, meaning very little oil returns to tank. The charge pump(integral to your hydrostat) feeds pressurised oil to the system for cooling/lube/make up oil. Usually between 40 and 70 psi. My guess is the volume of oil used by equipment pump overruled the demand for the charge pump. That would be a big plus for you. You could remove your hydro system for teardown and inspection, but I would think your damage would be limited to your equipment pump, control valve and working hydraulics. I remember reading on another site that a fella serviced a high end mercedes using a Napa filter. Long story short, it was mfd by wix for napa , came apart and choked all oil flow to engine. Months of litigation and the guy got his customers engine cost recovered. I try to stick to oem or Donaldson. Just what has worked for me.
IMHO it would be a big gamble not to tear down the hydrostat system for 2 reasons. 1, if there is debris in it you risk stuffing the drive motors completely. 2, if you have any recourse it's better to find the total amount of damage rather than trying to claim somthing later which may more expensive than the rest of the damage combined.
And you sir are absolutely correct.
OK. A few more questions so I can wrap my brain around this: What would be the cost for a shop to do this? About how many hours of labor for the above? Should I rebuild EVERYTHING with new seal kits? Hydraulic hoses are original and 18 years old, should they be replaced? Keep using the low pressure return lines(last longer than pressure side)? If the two hydrostatic pumps are clean do I need to take the torque motors down stream apart?
There IS another solution, get it working, and SELL...J/K, LOL!
It would be near impossible to get past the hydrostatic pump to the drive motors without harm to the pump. That said, it is not impossible. If you're attached to the machine. It would be a worthwhile investment to replace every piece of rubber hose. As Tones stated , it's better to lawyer up and perform a conclusive disassembly inspection and reassembly. I would also propably let a dealer or some other trusted 3rd party perform the service. The challenge is going be on you to prove regular routine maintenance was performed and that there was never any chance that the debris originated somewhere else. Its gonna be a rough challenge. Good luck
If I was dealing with this I would start small and at the beginning. If you don't find anything at the pump inlet I would just reassemble and put on a new filter (obviously from a different brand) Of course if you do find that debris have entered the pumps and motors it would be a different story.
Funwithfuel- Any guess as to the man hours on a job like this? Jacobd- Unfortunately it originated at the filter. It possibly contaminated the hydrostatic system too. Take a look at the drawing above and start at the 10 micron filter above to see the oil path.
The problem with your hydrostats is they're closed circuit, they only bypass a small fraction of the total oil, AND they're the most sensitive part of the system by FAR. Any debris in there is going to grenade quickly. On the other hand, this is not a $100k excavator, it's a used skid steer with a limited value. You're not going to come out ahead having this stuff rebuilt at a dealer vs taking the chance that it didn't get into the hydrostatic pumps. Also the wire is soft, as opposed to the hydraulic wire which is much harder and would be much worse for the valves and gear pump. I'd bypass the motors and put a filter in line. Run that side and examine for debris. Repeat for the other side. (Or put the filter in line with the motor and jack up that side) Call it good and present a reasonable case to Napa for reimbursement. I wouldn't worry about the gear pump, control valves, or cylinders. Unless or until debris shows up on a magnet or filter that suggests wire is still in there. Just economic probability, it's not worth tearing the whole thing apart IMHO, at this point.
I dont know your particular machine. I couldnt guess.. If i were doing similar job on a new holland or older case, i would guess to R&R pump assembly , adjust all linkage and change some rubber hoses, probably between 10-14 hours. Benchwork on the pump, no idea. I DO strongly agree with Delmer. You've got to weigh cost . Napa and/or their mfr is not going to overhaul your hydraulic system even though their part was defective. Progressive failure is hard to prove. The box usually states that your recourse is a replacement filter or your money back.
NAPA filters has a twitter account and none of these companies like bad press on twitter. I'm thinking if you posted a tweet telling them you had a bad filter they might DM you with a number to call. @NAPAFilters Might just ignore you too, never know. lol
Another thought just hit... See the smoke? Anyway, since the debris amount is small, and magnetic, take the drain plug out, and drill a short hole, in it, fer a small magnet, like they use in the plastic thumbtack magnets. It should catch some, if not most of the debris, in the tank. Might also be able to mount a microwave's magnet, on a line, somewhere too, like the bottom of the new filter...
After looking at the diagram I think you're probably right and the much larger flow through the spool valve and gear pump circuit carried most, if not all, the debris with it. Undo each fitting between the filter and drive pumps one at a time to see if you find anything. If not you're probably in the clear. Also, if you can, fish around in the reservoir with a magnet and see what you pull out. Check out the 100 micron filter too while you're at it. I'm betting most of the trash settled to the bottom of the tank.
My drain plug has a magnet on the end of the plug from the factory. Also there is a big magnet on the end of the suction filter. I going to buy some high powered Neodymium magnets and epoxy them to a couple of different lengths of fish tape. That way after I clean everything up with solvent and compressed air I'll make sure no steel is left behind. Took the hydraulic pump apart and it looks in good shape. Light scratches in the middle section where the outside diameter of the gears ride. Probably from the wire passing through. Bushings, shafts, etc are within Eaton tolerances. Going to get a a seal kit and put it back together. I did not find any wire in the pump, so I'm happy about that.
There are some small burrs I need to remove on the spool and the corresponding valve bore. I plan on using a fine diamond file on the spool edge(mounted on a lathe). But how should I do the bore? I am thinking of using a fine 600 grit ball hone for a couple of passes? My concern is I don't want to damage or change the close tolerance of this assembly. Please advise.
I'd go with a brake master cylinder hone, turn it by hand, don;t over do it, here...
Most grits on these types of hones are around 120 to 240 grit. Isn't that pretty rough for a hydraulic valve bore? My spools have a ground mirror finish. I'm guessing the bores have a similar finish?
Yeah, thats way too rough. I wouldn't polish the entire bore. I would needle file any high spots by hand. Any more than that, you're gonna have a drift issue, if you don't already
Wear it in by hand. Grab the spool with a vice grips or bolt a handle to it and rotate it in the tight spots until it moves smoother. i wouldn't use any hone, maybe sandpaper on the spool if it's bad enough that it won't go in.
You could allus wrap the stones, in fine sandpaper or emory cloth, to get the finish desired... I'd use oil, too...
I'm with delmer on this one, would definitely not start using power grinders and such on it... a little scraping goes a long way, some quality x-acto tools make for fine precision scrapers.