1997 D6M Ser# 9ZM00457 We are having a issue with our D6M Hydraulics getting hot. It Started with the left angle blade cylinder bleeding off while pushing a heavy load. Sometimes at idle you can hear a faint squeal in the hydraulics, you can make it stop by moving the blade. I original thought it was just a plugged radiator, but we had a fire engine stop by and flush it out very nicely. I'm now under the assumption now that the heat is being caused by bypassing in the control block somewhere. where should I start? This is a powershift machine, only thing the hydraulics run is the blade. Other Coolant & Trans run perfectly normal. According to my temp gun its getting to a little above 200*F and setting off the warning light. This takes about 6-7 hrs of moderate work. we let idle on half throttle and it comes right down, so the radiator is working great.
IN A D 5 H HYD VALVE THEY ARE SEALS ON WHAT THEY CALL A RESOLER VALVE THEY WILL BLOW AND THE 5H WILL NOT HAVE FULL PRESSER TO LIFT YOU COULD PULL WITHOUT PULLING VALVE BUT IS ON BACK AND METAL PLATE VALVE BOLTS TO IS IN WAY YOU CAN TELL IF THIS IT THE CAUSE ON STRIGHT BLADE BY WORKING TILT WITH LIFT WILL HAVE PRESSER NEVER HAD HOT ISSUE BUT THEN ONLY BYPASS WHEN YOU LIFT
We made it safely off the fire line, the next job we had it on the main hydraulic line from pump to control block blew! While I was bummed we had a failure I sure was happy to not be next to a active forest fire. We now have some time to properly diagnose this issue, It definitely happens more when its warmed up the left side angle will collapse under load. sometimes if you jiggle and mess with the blade controller you can make a normal push without anything bleeding back. Does this sound like the "resolver valve" ?
Angle cylinder bypassing internally?
I originally thought that exact thing, I had it rebuilt to find out that both rams are connected together. So fluid goes to plus side of one, while pulling from the negative of the other. They said the packing was good but the went ahead and rebuilt it. this leads me back to the control valve somewhere, I'm thinking i'll start with this Resolver valve and just start replacing stuff till it goes away...
A laser temp gun would be your friend here
That 4T-4525 Resolver Valve is nothing more than a shuttle valve to give it the correct title. All it has in it is a ball that moves from one end to the other depending on which way the oil is flowing. See the illustration below. Take it out, give it a good clean, then rattle it. Does the ball move with a distinct "click" from one end of the valve to the other..? If the answer is yes then my money would be on something else being the issue.
Swap the items labelled #25 with each other they are the circuit relief valves and see if that makes a difference
Forgot to add photo
in the grouve in resolver there is a hard o ring, part no 23 in picture , in d5h it will blow in lift side an not give full power to lift. if you work both lift and tilt you can make it lift better have replaced it twice on my machine,and you can hear it bypassing,never had it get hot but fixed to get power back. wish i could put circle around it but found the seal number 23 in brake down.
A good suggestion, and if you're going in there for a look-see I'd change O-Ring #22 as well.
Excellent, thanks for the ideas, I have a valve and o-rings on order with Cat. I'll give it a go and let you know
Bad resolvers usually result in weak hydraulics. Does it have a cooler? Neither the parts book or shematic show one. My money is on excessive case drain in the pump or a sticking swashplate or compensator valve keeping the pump upstroked and standby pressure too high. The 2nd makes the most sense in my head. When you hear the "squeal" and move the blade you're giving that pump flow a place to go. If there's any way you could get a gauge connected to the pump output that would be helpful.
Finally got the ol girl in the shop, decided to give her some paint while in there. The Resolver valve had very worn o-rings, the new resolver came completely assembled w/ orings and they were substantially in better shape. Hoping this will fix the problem, cant really test it though as we still have 4-5' of snow. Am planning on changing the oil and both filters since it did get hot enough to set off alarm
Another issue I've been trying to figure out is the Transmission filter light and alarm will come on randomly. When it first happened I immediately dumped the oil and changed filter. This lasted for a little while, it happened again and I changed the perfectly clean filter. Which lasted a couple hours. Now ive found it is a intermittent thing and if its beeping upon start up I can toggle key off-on and it will stay out. The sensor is $150 bucks, is there a way to test this before I replace? or any other ideas? Thanks
Do you have any Diagnostic Codes, either Active or Logged..? By the sounds of it there is a possibility of a bad harness connector somewhere. Electrical Schematic on the way. not so sure it's the temp sensor, more likely to be the filter bypass switch. It might pay you to check/clean all the major wiring harness connectors between the powertrain temp sensor/filter switch and the control, including the connector on the control itself. Also check the filter switch itself, because that's what is putting the warning light on. Have a look inside the transmission filter head where the switch screws in. There should be a spool (8) and a spring (9) in there. Switch is not shown in the illustration. Spool stuck.? Spring broke/damaged.?
Thanks for the schematic, I'll have a look at the connectors. Is die electric grease a good idea? or just inspect for corrosion and make sure they are pressed together tight? I'll pull the switch out as well and take a looksie at spring as well. Would it be a closed or open connection that turns on the buzzer/alarm? It does not have a screen for codes. I guess I need to make a click box if going further on that path. It is#5 in the picture (top right)
I see it is a "Normally closed switch that will open with an increase of a specific condition." Thanks Electrical Schematic. Maybe I can get it to re-create in the shop and wiggle around till it goes out. That stuff never seems to fowl up when you want it though!
Look at Grid A-8. There is a plugged filter switch and a temperature switch wired in series to ground and to the Monitor via vire 426-BR. The way that works is that even if the filter bypass opens when the oil is cold there will be no alarm because the temperature-dependent switch will be closed. As soon as the oil warms up above 52 DegC that switch will open. So if the filter goes into bypass (9X-7781 switch opens) after that point the Monitor is then no longer connected to ground and the plugged filter warning light comes on. The other power train switch in Grid E-1 is a temperature switch. It connects to the Monitor via wire 424-GY. It displays as "Power Train Temperature" in the top LH warning light. So if the oil temp rises above 107 DegC that light will come on and stay on until the temperature drops below 93 DegC.
Thanks for explaining how it works, hard to get my head around the schematics sometimes. So if the machine is dead cold and below 52*C it shouldn't be able to illuminate the light and alarm correct? (which it intermittently does) I inspected the wiring to switch on the filter housing (power train filter switch) and followed it down to the (power train filter bypass switch) and everything looks good working order. I tried to get the light to illuminate with key switch on by jiggling wires to no avail. I then unscrewed and disconnected the wires going to the power train filter switch (23) and jumped them together. Still nothing, But I guess if the "Power train bypass switch (19)" was not up to 52*C it would not come on. I then unplugged the harness near the component "Conn 2" and this created the light to come on. This all sound normal to you? Anything else I can try?
Correct. With a trans oil temp of less than 52 DegC the plugged filter light should never illimunate. Try this. Remove the 3E-9350 filter bypass switch and measure the resistance across the terminals of the 2-pin connector - it should be zero indicating that the switch is closed. Put the switch in some water (your wife's stove will do fine for this) and gradually increase the temperature. When the water temp gets to 52 or thereabouts the switch should go from closed (0 ohms) to open circuit (OL or similar) on your DMM.
here is some info that may be of use
It works 98% of the time, so my luck the times I'd test it, it would work normally. What I'm contemplating is how toggling the key switch would fix it. Is there a transmission ground strap? Is it possible the transmission isnt getting good ground, or at least intermittent ground? Thanks for the files Mark!
Based on the articles Mark posted you might be advised to remove the switch, clean the threads both on the switch body and in the housing it screws into, and reinstall it. Note the comment in the article about NOT using PTFE tape to seal threads (buggers up the resistance) I would've thought there ought to be ground straps both from the engine and the cab to the chassis. There's certainly a ground connection for the cab wiring right below the circuit breaker box.
my light problem was the short harnes that lays right on filter base not more than4 inch long that goes to switch looked like a rub and heat
Definitely wont hurt to clean up the grounds. I imagine the temperature switch sits in the oil pan. Unfortunately I don’t have any oil to put back in if I lose some. We are currently “locked down”
Yes, I saw that one, I will re-inspect again, throw some zip ties on it. Thanks for suggestion
Correct. Just remember as soon as the control sees ground the light will come on. So if the insulation of a wire is rubbed through, that's your culprit. However ......... your symptoms of being able to "reset" it with a key switch Off->On cycle seems to suggest more of a poor connection somewhere. Although, as if to counteract my own argument, it could be nothing less than engine vibration (or a lack of it) that either causes a wire either to rub against something structural when the engine is running, or not, when the engine is stopped. It could be that a good clean down in the Hell Hole might well reveal something rubbing if your photo above is anything to go by. If you're locked down maybe an idea to drop the belly guards and have a look up from underneath..? The switch BTW is located on the RH side of the transmission - Ref #24 in the illustration.
Well I dropped the bellypan and wiggled the wires all way back up through the main harness to no avail. I went ahead and put loom around the wires by filter housing and secured them. I disconnected and cleaned the lower filter temp light and was able to tighten the threads a very little bit. I cleaned all the grounds by the fuses. The main connection at bottom of “hell hole” where Master switch negative also bolts up wasn’t loose, but also wasn’t very tight. Got everything cleaned up and bolted backdown. Not super conclusive but maybe enough to fix a intermittent problem. Time will tell! Thanks again for the help and suggestions
Looks like it would benefit from a good dose of the pressure washer while you have the guards down.
Got her finished up!, sure do like new paint! Anyway, got it out and started plowing snow. Trans filter light stayed out.. for now. The blade bleeding off issue unfortunately was not resolved with the new resolver Still likes to bleed off (Angle Left) under heavy load. Things I've done - Rebuilt Left Cylinder, I understand they are both connected together, could the right one be bad as well? Cylinder place said the seals didnt look to be bypassing, but they rebuilt it anyway. -Swapped Pressure reliefs from top to bottom on the Angle control block - No change -Replaced resolver with new from CAT, old one looked to be worn, but no obvious damage or o-rings missing. -Changed hydraulic oil since it got hot this summer, cut open filters, Did find a small piece of rubber, half moon shaped about 3/8" possible o-ring. When I was running today I was trying to notice anything I could to help diagnose. I thought a few times it could have been bleeding off to the Right side as well, not nearly as fast, but I did have to straiten up the blade a couple times. But it wasn't extreme like the left side. What else can I try, Diagnose, Ideas? I'm open for suggestions! Thanks!
Are you saying that the hydraulic overheat problem is solved, and that you only have the blade angle changing under load?
Hello Mark, I believe the hydraulic overheat problem is the connected to the blade bleeding off issue. I think its bypassing somewhere and generating heat, eventually creating the overheating issue. I only ran it for about a hr clearing snow. It didn't over heat in that time frame. Today I was explaining the problem to one of our guys and he reminded me we did blow a hose a couple years ago on the left side when he hooked a frozen rock. Not sure if it could be helpful information. But its been a progressive issue, slowly getting worse. Thanks, Sam
Could it be a small piece of steel lodged in the left angle valving? Should I take this valving apart in the handle and inspect or is there a way to test if its seating properly?
*Update* I angled the blade fully to left, then took off the forward line on left ram and capped hose. I then dead headed it and fluid came out of the ram! I tested the other side that had been re-sealed and it did not leak. So I pulled right ram apart and low and behold she's been bypassing. I was disappointed but happy I've found the issue! Now im on the hunt for a new cylinder, $$$ ,ouch. Thanks for all the suggestions and ideas!
I was under the impression that you had both angle cylinders checked and resealed There have been a number of issues with these cylinders and they were changed out years ago. There are some mods you can do your self Check out this service bulletin from cat
So what is the piece of steel at the bottom of the barrel which damaged the piston. Where did that piece come from?
I just had the cylinder on the side it was leaking on resealed had a 50% chance! knowing how the system works now, i should have tested both long ago, hindsight! Interesting about the bulletin, I tried to get the piston nut off with 175psi and 1" ingersol impact and 36" pipe wrench to no avail. I cleaned everything up and ordered a new seal kit. But it just looks too deeply grooved, I'm sure it would be better, but for how long? A rebuilt cylinder looks to be about $2k which I dont like, but is probably the safest way to go. Not sure about that, I originally thought it was a keyway that met up with the piston rod checkvalve thing. But after closer inspection its balled up metal! best I can tell is its just galled up metal from the bore, bunched and smashed into a ball. Or someone left a ball bearing in there.
I've seen lumps of metal from that piston check valve make marks like that before. IMO the check valve fell apart and one of the loose pieces dropped to the bottom of the cylinder where the piston smashed it against the head a few times, encrusting it into the piston (I've also see it a couple of times where the loose piece was embedded into the head of the cylinder). At that point it also mushroomed the piston slightly and that's what then gouged lumps out of the cylinder barrel.
Looking at the pictures I thought the piston unloader or check valve looked intact. Maybe not it is looking a little off Center.
To me it looks as though the spool is sitting on the bottom of the outside collar which is usually the result of one of the seats falling apart. To the OP - I hope you are aware that unless you fix that check valve in the piston that the cylinder will still bypass..? In fact that’s most likely where it was bypassing when you tested it before removing the cylinder from the tractor.
Not sure what that is supposed to look like, but it moves around quite freely and the little shaft going through is independent from one side to the other. My book doesn't show a break down of this. Thanks, I have a new/rebuilt cylinder on the way. Glad I didn't try to re-seal and salvage this one!
This is not necessarily your cylinder but it's the best illustration I could find to show the relief valve in the piston. Note that there is a spring (# 3B) in it. The spool of the valve is not supposed to move...........
Well hell, Got the $2k cylinder put it on there. Went out plowing snow and it worked great for about 20 minutes. Then the problem returned!!!!!!!!!!!! So I started pushing some snow and gravel in a slot in the pit and it folded to the left every pass down. I then thought I would video it.. Well it went away! I did get it to do it several more times. But the fact that it can be intermittent and not constant makes me wonder even more! This thing is driving me nuts! Once parked I was messing around with the blade control. I found a detent in the blade lift control that I dont believe should be there. With the weight of the machine on it, it stays in this detent mode and the pump just growls. With no weight on the blade, it slowly lifts the blade. Is it possible that the angle control block could be bypassing into the lift block? What else can I try? At a loss at this point, shes a beautiful turd. Here's the video of the blade
I think it might be worthwhile to get into the control valve. The operating mechnism is 100% manual so whatever resistance you are feeling ought to be coming from the inside of the valve itself. Maybe try disconnecting the linkage somewhere in the red circle and then see if the lever moves freely..? If it does you know the resistance you are feeling when the linkage is connected must be internal to the valve.
Thanks for the suggestion Nige, I went out there last night and took the cover off. The up and down function's heim joints are definitely wore out. Wont hurt to replace them. It appears that the piston returns to center each time. I cound feel no indication of that "detent, stickyness" I was feeling in the video. I fired it up and performed the same test in the video and it would not re-create. I'm guessing, something, once warm, swells up and becomes un-happy. I plan on running it until acts up and take a video of the functions. Maybe the lift isn't returning to zero? Thanks for staying with me on this, I'll post findings.
Do you need the Parts Listing for the controls that the above illustration was taken from.?
Thanks, I found it in the parts book
Okay! I finally got to run it and do some testing! I changed all the lift hiem joints. Unfortunately that didn’t change my problem, but definitely needed to be done. I was pushing dirt and when it started bleeding left. Sometimes it can be intermittent so I was determined to find out what was being done, I tried lots of combinations and came upon a fix! If you fully angle right, then left, then back to center it will be rock solid! Till you angle left again, then it starts all over. Does this help narrow it down, I hope!? It’s like something in there that tells it to change flow paths isn’t closing. I changed the primary resolver, could it be the secondary?
Any Ideas?
Seems to me you have a problem with oil bypassing back to tank when the blade is loaded, which makes me think of a problem in the control valve 6E-4954 . Looking at SIS for that model tractor, the control valve for the angle has two relief valves in the control valve. Relief valve part number 6E-0772. You could swap the relief valves around and see if the problem swaps sides. That is where I would be looking, in the control valve bank. If the problem was only in one cylinder the other cylinder would still be locked
Also looking at SIS it shows a piston hydraulic pump. Which to me means a closed centre hydraulic system. If it is a closed centre system, and there is an internal oil leak somewhere, then the hydraulic pump is going to be pumping all the time, leading to heating problems. Closed hydraulic systems is the system is always at full pressure and the pump varies it's capacity output based on demand. Open centre like on much older machines, the pump pumps the same amount of oil all the time and the pressure varies on demand. So when you put the blade down there is a pause until the pressure builds to get down pressure.
Interesting, I have wondered about the delay on older machines. Unfortunately I did swap the reliefs when this whole thing started and it didn't change sides. I agree it is most likely in that control valve somewhere
*Update * finally fixed! It was the relief valve in the end of the piston. I had this off already and explained the problem to a hydraulic shop, they said everything looked good and they put new seals in it. Almost a year later we tore into it to fine the check valve do-dad was stuck in end of piston. Works like a champ now! Thanks everyone for all your help. Also my mechanic friend who swapped cylinders from side to side to pin point the problem. I’m ready for the next problem
Obviously not much of a hydraulic shop if they didn't verify correct operation of the piston check valve while they had the cylinder disassembled. My opinion (*other opinions may be available)
Yes I completely agree, they are super nice people but do terrible work! I've had pins (2) lathed out of round. Track chains that were ordered 3 links to small, A cylinder that took a month to rebuild that turned out it was mixed up and not even my cylinder. They stood behind everything but unfortunately this will be the last straw.
I know lots of nice people but there are certain of them that I wouldn't let them within a country mile of anything hydraulic. Nice does not equal competent in my book......... Look how much pain this has caused you (and the time taken to sort it out) simply because the shop didn't do their job correctly when they disassembled and resealed the first angling cylinder. The assumption all along was that the resealed cylinder was "good" simply because a hydraulic shop had overhauled it and any normal person would've thought that they would have checked and verified the operation of the check valve during that overhaul.
I have been told a thermal imaging camera can be used to diagnose an internal leaking cylinder.
It can indeed. I don't know how well it would work on one with a piston check valve though.