I have a 409E with about 8,000 hours which suddenly went slow in all modes. The problem was no more than 2,000 PSI from main pump. Removed main pump for internal inspection by hydraulics shop, no issue found. During 4 months of searching, Replaced: 1. Main Pump solenoids. 2. Angle sensor 3. DP Sensor 4. Fuel filter 5. Cleaned hydraulic filters, air filters 6. Replaced PVC 7. Cleaned all connections 8. Service Tech finally showed up and found a broken spring in one of the main pump solenoids. Replaced that solenoid. Max main pressure then 3,800. 9. Tech returned and said engine injector pump was not meeting specs. Removed and had engine injector pump overhauled with no improvement noted. Tech says no issue with PVC or its sensors per his computer. 10. Overhauled the system main relief valve and replaced the surge relief valve with new. This allowed adjustment of surge and main pressure specifications. Thinking I had solved the problem, I attempted to return the machine to service. Functions are weaker and slower than before with the engine wanting to stall. Operating temperature soon rose to near red line. The hydraulic oil was so hot steam came off the bucket cylinder when digging in water. I believe I have a hydraulic by pass somewhere. My question is how do I find it? Is it trial and error, or is there a methodical way to find it? Any and all experiences and/or suggestions, short of throwing a match on, it would be appreciated.
One thing you haven't listed is pilot pressure and flow. If that is low then the main control spulls won't open fully and will create heat and make the engine labour.
Those 2 pump solenoids control pump output-- 1 strokes pump for more output, the other de-strokes the pump-- they sort of fight each other while running to keep pump where it needs to be--normally you hear a clicking/pulsing when running at low speed and stand next to it. Does it sound like its under a load when you first start it? With all those parts thrown at it, could it be as simple as someone connected the 2 solenoids incorrectly and its trying to put out oil when its not asking for oil? They both have the same connectors. Also there are adjustments that need to be made to the angle sensor as well as the D/P sensor-- also if engine speed sensor isn't reading, it can do odd things as well.
I agree with Jon. If you have a volt meter you can set the pump angle sensor and the dp sensor .W.e had a jumper or break out connector but you can make your own.Make a tee connection at the red/yellow wire going to the pump angle sensor and another tee at the black wire.Disconnect the 2 pump solenoids ,start machine at an idle and wait 3 or 4 minutes .You should hear the engine start to labor as the pump goes to full stroke.With the volt meter hooked in loosen the 2 screws on the angle sensor (leave snug) and adjust until you read 4.5 volts.Tighten the screws and recheck.It is a very sensitive adjustment so fiddle with it until you get 4.5. Hope fully that will solve your problem.If that adjustment is off the pump doesn't know to stroke or de stroke witch will account for the low pressure and the heat.Another useful tool to get is a temp sensor.Point it at the control valve and check what is the hottest.That should narrow down your search for what is bypassing.
Thanks for your inputs. Joe, my manual says 4.40 V on the angle sensor which is where it is set. The DP is set where found at 1.14V. The Tech recommended 1.0V on the DP. I installed a new DP set at the minimum manual recommendation of 0.5V and it made no difference. I read in the manual that turning the DP down slows the machine operating speeds. The pressures on the pilot circuit is according to manual. With the PVC and all sensors functioning correctly according to the computer, i believe the problem is internal leaks pass one or more relief valves, with the dumped pressure creating the heat. I read in another post on this site which offered, "I would suggest you look at the small solenoid valve box and reseal it. That is what did the trick for us in the end. I can't remember exactly what but think it had to do with how the valve box affects the load on the DP sensor. So too much pilot oil makes the DP sensor think more flow is needed and maxes out the pump and ends up being dumped as excess heat." That seems to be the situation with my machine, that is, pressure is being dumped creating excessive heat. Yesterday I ordered all the seals for the small solenoid box just behind the cab. They will arrive tomorrow and we will go through it. There are a total of 10 valves in the housing, so we will go through them all resealing, reset the pilot pressures and try it again. I have purchased the harness from JD for use in setting the A sensor and the DP sensor ($135). I also have a temperature sensor gun accurate to 0.5 degrees. I also have the gauges and connectors to monitor and adjust the main and pilot pump pressures. I will reseal that solenoid assembly first and if that does not work, I will bring out the temperature measuring gun. There are so many relief's in the system, finding the internal system leak is a real pain. 4 months of searching, adjusting and repairing, two technician service calls, thousands in parts, and the machine is still not returnable to service.
Sounds like you have been through the ringer with this machine.As I remember the biggest problem with the 490E was the relief valve getting contaminated and those pump solenoids calving.Since you have a manual, check #7 check valve and the unloading valve.Be sure to put a vacuum on the tank before removing unloading valve . Other than that I cannot think of another thing that would dump that pressure. The settings on the angle sensor and 0.8V on the DP sensor came from JD Detac.They also suggested cranking the pilot pressure up 100 psi. Good luck
Thanks again Joe for your reply and continued interest. These problems only started after my operator slid the machine into the pond we were digging. He was frantic to get the machine out of the water and I believe he overheated and/or overloaded the hydraulic system in the process. That one pull out cost me $750 for a very large wrecker. The machine has had problems since then, but for the past several years before that has performed reliably, just blowing a hose now or then. Additionally, in the past both track tensioner springs have been broken and replaced. We have replaced the pins and shims in the arm and bucket, installed new bosses on the bucket and painted the machine. Right after getting the machine 7 years ago, I pulled the pivot motor and replaced the main shaft seal to stop a major leak there (that is why the prior owner sold it). I also found the prior owner had removed the screen on the hydraulic oil return in the tank. Then the computer went south due to an angle sensor failure and the fact that the prior owner had installed a 5 amp fuse in the 1 amp slot for the computer. I do not blame the machine for problems caused by poor maintenance. I have put a couple of thousand hours on it largely trouble free until now. Tomorrow we will get into those valves. Considering the machine is 22 years old, new seals can't hurt.
Yesterday we pumped 15 gallons of hydraulic oil out of the tank and into new clean hydraulic oil buckets for reuse and to prevent loses while we removed and completely overhauled the pilot solenoid valve body. We found one broken O-ring, but all were hard. Each and every one was replaced with new and and the valve body has been reinstalled. Today we are attempting to remove and overhaul the number 7 shuttle valve in the main valve body. The parts diagram shows only one O-ring, but it has a screen inside the valve body which I would like to inspect. Removing the shuttle valve cap was no major issue, but now we are having problems in determining how to get the valve body out without damaging it. All that we have tried does not work. Does anyone know how to get the valve body out without damaging it? ANY and ALL suggestions would be appreciated.
After further inspection, we found that the valve is threaded on the inside to allow insertion of a screw for removal. Full of hydraulic fluid, it was not easy to see. Careful on removal, once it broke free it went flying. Inspection of the valve body internal screen showed it was nearly blocked with fine particles of what appeared to be o-ring material. Would that cause problems with the DP sensor signal or cause a by-pass contributing to the overheating problem? We are now reinstalling the cleaned and resealed number 7 shuttle valve, then onto pilot pressure adjustments. I will post the outcome of this work.
You may have found the problem.#7 shuttle valve sees highest work port pressure which is called load sense .That oil works on the DP sensor which tells the pumps to stroke or de stroke.It also works on the top of the unloader valve which dumps pressure relief oil back to tank.Since you have all the oil out of the tank it would be a good idea to pull the unloading valve spool and make sure it moves freely and the spring is in good shape.I think you are making some progress. The E series was Hitachi first stab at computerization and were a steep learning curve for us old school mechanics. They went back to the dash 1 system in the dash 5 with a little more finess.One thing you have to say about the Japanese is that they learn from their mistakes.North Americans not so much.
Gentlemen; We completed the overhaul of the complete solenoid valve system. I increased the shims 0.10 attempting to achieve Joe's recommendation for 100 PSI on the pressure regulator. Only got an 80 PSI increase. The flow control valve after overhaul was erratic from 200 to 600 PSI, so I replaced it with new from JD. Now it is in the manual's range. We ran the machine for about an hour and still had the overheating problem with the hydraulic's. Using the heat gun, I looked for the source of the heat and found the arm control valve was hottest at 175 F. My question now is should I replace the relief valve for that function, overhaul the control valve for that function, both, or do them all? Scanning the hydraulic oil cooler, I had 134 F on the input, and 132 F on the output tubes. The auxiliary valve and the boom valves were about 7 degrees cooler, so I contributed that to heat bleed over. It appears the arm control valve is the source of the heat, so how should I address it? All advice will be sincerely appreciated.
Ok ,I have a few questions.Did the pressure come up and the speed return? Did you pull the unloader valve? Is the machine functional now except for the heat?Does the arm drift or hesitate when you pull it in?What is the temp at the cylinder?Have you pulled the return filter and looked for contamination? The 490E and the 790E have the same system and are prone to weird problems if you have any contamination.Since you pulled this machine out of the swamp you may have bent the arm cylinder (seen it happen).You can pull the shuttle valve for the arm the same way you pulled # 7 shuttle valve.Since you did find contamination in #7 chances are you will find it in the arm shuttle as well.If you have had any contamination producing event ( cylinder piling up ,propel or swing motor producing metal etc..)You can chase those little gremlins forever.I don't mean to dishearten you but for every problem there is a cause and you have to look back to where this problem started.
Joe, Yes the performance of the machine has returned. The first thing we did was remove and inspect the hydraulic filters, as well as the tank. No issue was found there. The problem now is the heat. Today we ran it some more (dug up a stump), and searched all over for the source of the heat again. We found that the flow control valve behind the cab is the heat source. It is returning the hot fluid to the solenoid valve body, heating it. The cylinders are cool, but the flow control valve body will burn you, particularly on the forward side. We are now removing hydraulic fluid again so we can remove that valve body and overhaul it. The infra red heat gun has been a valuable resource. It will be next week before we get'r done, but hopefully and prayerfully, this should finally solve the over heating issue. Today we should get the flow control valve removed, disassembled, inspected and get the parts ordered. I do sincerely appreciate your advice and assistance to date. I will advise of the success (or failure) of this effort.
Today we removed the flow control valve, disassembled, inspected and cleaned it. No issues were found there. It was reassembled and returned to service. Tomorrow I will remove and disassemble the left pilot control valve. That is where the hottest line was coming from. It is delivering hot hydraulic oil to the flow control valve. I will advise on the results. Continuing with the hydraulic over heating is not an option.
Yesterday I removed, disassembled, and inspected the left pilot control. I could not find any diagrams of the assembly or its internal parts listings. JD wanted $1,750 for a re-manufactured unit. The internals of the unit are fairly simple with a standard o-ring sealing in each control valve (replaced from my stock), and held in by the top plate. Unscrewing the control handle releases the plate Each valve is simply a piston with smaller internal end inserted slide valves actuated by a spring. The pistons are manufactured with one small (about 0.010 ) passages drilled through one side of each piston above the internal pin. Inspection revealed that three of the four piston's vent holes were blocked with black looking debris. I used a fine wire and acetone to reopen the vent passages and cleaned them and the housing thoroughly, then reassembled the unit. Each of the valves have a wiper seal on the exterior side of the operating plunger. Since none of mine were leaking, they were returned to service. Does anyone know if the blockage of those vent holes would cause an over pressure situation leading to heat generation?
I don't think your heating problem is coming from the pilot control valve .If its not leaking leave it alone(they can be a bit of a bear if you have never done one before )If you do take it apart make sure all the plungers go back in the same holes and the little metering pistons go in the right way (small end up) From the temps you are getting at the inlet and outlet of the hydraulic oil I would guess it was plugged(low air flow) There is also the cooler bypass valve that sticks sometimes but your main heating problem is not coming from the pilot circuit .I would say there is something in the main control valve heating the oil>
Just read your last post while I was typing mine.Those little vent holes control your ability to meter a function as do the internal pins.The pilot system is open centre meaning that all the oil being pumped by the pilot pump has to flow back to tank.Have you checked the pilot filter? Is the machine a little jerky to operate?Hard to say where black looking debris is coming from but the pilot side is completely separate from high pressure side .
Joe; Again thanks for your reply. Yes the pilot filter has been checked with no issue there. I did not even know there was flow control valves in the oil cooler piping, but the low temperature differential across the oil cooler does seriously bring those valves and the cooler's operation into question. We have before externally pressure washed the oil cooler coil itself and it appears to be clear. Because of the heat, I have had the radiator boiled out and rodded. That made no difference either. I removed the engine thermostat and ran the machine with it out. Again no change in operating temperature. I will definitely get into that hydraulic flow control tomorrow. I see two hydraulic control valves in the system, one from the main valve control body at the tank and another in the cooler piping. What is the purpose of those valves? The left pilot control valve has been out before (apparently by the prior owner), as indicated by markings on all the ports. I slowly went through it making certain everything went back as it came out. The operator reported he was getting feed back through that control. The hottest areas we could find with the heat gun were at the regulator valve body feeding back from the left pilot control, that is why it was investigated. We have not found metal anywhere in the system, just very small bits of what appears to be o-ring material. It could have been burned bits filling the pilot piston vents, but it was hard stuff. I intend to chase this rabbit until it is found!
In your first post you mention that you overhauled the main system relief valve. What did this include? The reason I ask is that years and years ago I had a Deere 490 excavator (no letter suffix, just straight 490, no computer, no pilot hydraulics) that developed a problem where in hard digging the functions would slow way down coming out of the hole and swinging, but release the controls for an instant and it would return to normal until the next cycle. And when it was doing this the hydraulic temperature went crazy. Dealer thought it needed a new pump, but it turned out to be a/the main relief valve. I think it was pilot operated relief, but can't remember as it was a long time ago. Anyway, there was a small cone shaped poppet that had a very slight annular groove worn into it by the seat. Slight, like visible but barely perceptible to a fingernail. I polished it out by chucking it in an air drill and dressing with a diamond file. Problem solved. I think what was happening was in a hard dig the relief valve would open and then not seat completely until the pressure dropped enough, which would happen each cycle when the bucket was dumping. I don't know if this has any relevance to your problem, but thought I would mention it as it kind of sounds like you have oil bypassing somewhere.
There are two bypass valves in the return section.One is used to create a back pressure to prevent cavitation at the swing motor.The other works when the oil is cold or the cooler plugs up and opens a straight return to tank,kind of like a thermostat in the engine (which you should never run without)The optimum temp for the hydraulic oil is 120 degrees F plus or minus 10 degrees. This depends on a lot of factors.Oil viscosity is a big one and should not be overlooked.Ambient temp is another one.In the Southern US where the temp stays in the higher range than it does up in Canada ( it sometimes gets too hot up here and igloos melt and homeless eskimos become a problem)sorry bad joke. ,A higher viscosity(thicker) oil would be recommended. If your speed and pressure came back after you cleaned up shuttle valve#7 than you were probably heating your oil through the unloader valve. If it stays in the 125 to 130 F range then you should be alright. Deere recommended hydraulic oil be changed every 2000 hrs and if running a high heat producing attachment like a hammer then change it every 1000 hrs.When the oil becomes oxidized with heat and age it creates a whole new set of problems.Waxing is one of them that makes all your cylinders leak and all your valves get sticky. I know that you have already spent a lot of money on this machine but changing out the hydraulic oil will benefit you in the long run. A semi synthetic oil has a lot of advantages as it does not oxidize as readily as a straight mineral oil.And don't chase that rabbit down the hole ,thats how Alice got in all that trouble.
Not familiar with the machine , but the temp difference across the oil cooler seems very small like Joeblow said . If the oil cooler bypass valve was at fault the temp difference would be higher, not low like this . Could the oil cooler have internal baffles ? Next time it is running check the temp all the way down along the middle of the cooler . Are the fan belts up to the job ? Some hitachi models have suffered from poor bonnet design , not leaving enough air to the rad .
Thanks to all! Yesterday we removed the valves in the return oil system, operated them and inspected them. No issues found. We also removed and resealed all the main control solenoid valves. Today we ran the machine for about 3 hours (40-50F outside) in hard digging before the machine ran hot hydraulically. Measuring hydraulic oil temps showed near 200F in the oil return lines, but the oil cooler and reservoir remained cool. I continue to try to determine why the heat is not getting to the reservoir and the cooler. The valve condition mentioned by Bryan does not exist in this machine. Something is stopping the flow to the cooler and the reservoir.
Volvo, We have resealed the compartment and between the oil cooler and the radiator. Fan belts are tight and in good condition. The heat is simply not getting to the cooler or the reservoir.
Gentlemen; Today we took the cue from Brian and Joe to look harder at the main pressure relief valve. We removed it again, visual inspection of the valve internals revealed nothing. It has been resealed with the parts from JD. I put the cone Brian referred to in a drill and turned it against a flat honing stone. There was a significant land on the cone, not apparent to the eye. Honing it off in a drill took about 30 minutes. The valve was reinstalled and pressure reset at 5,000 PSI. In setting the pressure, it was noted the piping to the bucket cylinder was quite hot to the touch. (bucket over relief is the instructions for pressure setting) I do not know if this is normal or not when going over pressure relief. Testing the machine afterwards, it continues to run hot hydraulically. Needless to say, I am frustrated and annoyed in trying to find this hydraulic overheating problem. Any and all suggestions as to a cure will be sincerely appreciated. I cannot recall a situation that has been so difficult to solve. If it needs a new pressure relief valve, I am willing, but I would like to know if it will solve the problem. I went to a recommended independent repair shop today and discussed the situation with the owner. He wanted no part of it, saying I may or may not ever solve it. Obviously I need some help or advice from someone who knows more than I do, and more than he does. PLEASE?
Have you checked the circuit reliefs ? If the main relief and the circuits are set too close together than it will heat the machine hydraulics.Remember that there is another relief on the bottom of control valve called the surge relief and it must be set to spec as well. It is a puzzle that the reservoir and the cooler remain cool but the hydraulics heat up.That oil has to return to the tank . Is the oil foamy in the tank ?Try removing the cooler bypass valve and see what happens to the hydraulic temp .Also check case drain at the swing motor.Oil bypassing at the valve plate will make the swing noticeably weak but also heat the oil. If there is a JD dealer near you then ask him to put a search on the Detac system.If he is a good guy then he should help you.For all the parts you bought off him he should be your best friend.Dont lose heart ,I think you are almost there.
Joe; Thanks again for another clue. The JD dealer mechanic has made two service calls on the machine already with a 30 year experienced mechanic. On the last one he recommended overhauling the engine injector pump which was of no benefit. The swing motor is working fine and temps there are well below the others. The surge relief was replaced with new from JD and set to as I recall to 5,300 PSI. The main relief is set to 5,000. The oil cooler bypass valve to remove is the upper one correct? The machine works fine in all modes but working it just generates heat in the hydraulics. Four months of working on it would frustrate most anyone. We will do as you recommend. Today I leave for Boston with my wife for two weeks to keep our three grandchildren there while the parents go to a wedding in Florida. Maybe the break will help, but to me it is a constant puzzle which I must solve.
I love a good puzzle.I like it a lot more when I am sitting my fat ass behind a computer screen with lots of time on my hands rather than standing in a muddy ditch with rain pouring down the back of my neck and an irate customer wondering when his machine is going to be fixed. So let us summarize here .The machine is up and working again ,pump solenoids replaced ,angle sensor and Dp sensor replaced and set up,new main and surge reliefs,new pump valve controller,new injection pump,resealed pilot valve and controller and hydraulics still over heat yet oil cooler and reservoir stay cool. And it does not heat right away but will after 3 hours of heavy digging. I would try removing that cooler bypass valve (at the top of the cooler )and see what happens. Did you ever look at that unloading valve and the spring?If the spring gets weak or the passages in the unloader spool get plugged then it might allow the oil to bypass and heat.It is an extreme long shot but you have come this far and short of a bad circuit relief or a rag stuck in the cooler line ,that is the only other thing I can think of.
What is the reservoir temp ? How does the machine operate when hot ? Are the cylinders running at similar temperatures when working hard ? How hot are they ?
After all we have done, yesterday we ran the machine until it reached red line on the temperature gauge. The outside air temp was 61 degrees Fahrenheit. These are the readings I recorded using a infrared heat gun after hitting red line: Bucket cylinder 110 F Arm cylinder 113 F Boom Cylinder Left 122 F Boom Cylinder Right 123 F Rotating motor 168 F Drive Motor Right 91 F Drive motor Left 78 F Inlet to oil cooler 165 F Outlet of Oil Cooler 136 F Pilot Pump 176 F Main Pump 180 F Hydraulic reservoir 166 F Pilot Control Block 155 F Main Control Valve Block 171 F Reservoir Return oil line 162 F Reservoir Supply Oil Line 162 My internet search results say, "Hydraulic fluid temperatures above 180°F (82°C) damage most seal compounds and accelerate degradation of the oil. While the operation of any hydraulic system at temperatures above 180°F should be avoided, fluid temperature is too high when viscosity falls below the optimum value for the hydraulic system’s components." I have exclusively used JDM-J20C specification Hy-Gard Hydraulic fluid as recommended by my dealer, with manual specified OAT of -4 F to 122 F. The manual also allows Mobile DTE 25 with a specified operating range of 14 F to 122 F OAT. Any and all suggestions would be appreciated! Normal hydraulic system temperatures should be in the 120 F range. Could it be that the hydraulic fluid viscosity is too low for the outside air temperature? We rarely see 32 F in our area of operation, with summers reaching as high as 110 F. Would switching to Mobile DTE 25 possibly lower the hydraulic system's operating temperature?
Does it make a whining noise when you swing? And did you remove the bypass check valve at the cooler? From the temps you describe it the over heating could be a bad crossover on the swing.
Joe; We removed the bypass in both the cooler return line and cooler supply line individually, tested the machine in operation with no change noted for either valve. They were cleaned, inspected and returned to service. No whining noise is apparent on the swing. I also continue to wonder why anyone would remove the return filter screen in the hydraulic reservoir as was found when I got this machine. What would be the definitive test on the swing cross over? I see a leak test in the test manual for the machine's swing motor. Would that test be definitive?
Joe & All; I found the crossover relief valve test and adjustment procedure in TM 1504. What you are saying makes good sense to me. We will perform that procedure ASAP. Will advise of results. But, if those relief valves are set below current system operating pressure they could well be the source of the hydraulic heat we are experiencing. Many thanks for your suggestion!
Today I attempted the cross over relief valve test and adjustment. Initially the pressure was 4,200 left and right with the main relief valve and surge valve full in. I removed and resealed the swing valves with new o rings and adjusted them full in getting only 4,400 psi. It appears the pressure is going somewhere else. Any and all suggestions would be sincerely appreciated
Did you check the swing motor case drain? (swing motor leakage test)
Joe & Mike: I did not perform the leakage test, but will certainly do so. It is puzzling to me that the main pressure and surge pressure can be set to specs, but with those regulating valves fully closed, and the swing regulating valves set fully closed, the swing system will not come up to spec. I am guessing the swing motor leakage test will show if is going through the swing motor or somewhere else.
If high pressure oil leaks past the valve plate (thrust plate) in the swing motor then you will get excessive leakage.And wherever you have high pressure oil trying to get past a small area then you will get heat but I think you already know that.Its the cross over reliefs that stop the swing and not the brake but if you had that much leakage to create that much heat then the swing would be noticeably weak.Your temp check was very telling in that the swing was the hottest circuit you had. Another quick diagnostic check is cycle times .It is very important though that your W.O.T (high idle is correct) I think we are finally getting somewhere.
Today I performed the leakage test on the swing motor per the manual. Got less than 2 gallons total pushing against the ditch bank at stall for 1 minute left and 1 minute right. Swinging right and left for a minute gave me less than 1 gallon total, so it passes the swing motor leak test (and made me dizzy). We now know the swing motor is not the problem, but there is a problem in that system. What next?
I am trying to understand what is going on within this high pressure system. Considering I can adjust the main relief and surge relief to specs per the manual, but with them both screwed full in, I can only get 4,400 on the swing cross over reliefs (with both of those screwed full in), it leaves me puzzled. I ran the swing leak test with them all 4 screwed full in, thinking that would provide the highest pressure at the swing cross over reliefs and hence the most leakage. Was that a mistake? Tomorrow, I plan to go through both control systems again. I will first test all the pilot control solenoids electrically looking for the 10 to 50 Ohm specification from the manual on each, then readjust each pilot control circuit pressure per the manual, then readjust the main pressure circuit for each, then try the cross over relief settings again. The by-passing fluid is creating excessive heat and the source must be found. Any ideas or suggestions from other experiences will be appreciated.
The crossovers are separate to the swing as the circuit reliefs are separate to their respective circuits.The only place for that pressure to be lost is through the swing motor or the valve spool(very very rare).Since the highest heat you measured is coming from the swing motor ,I would do a few more checks on that.In the O&T book there are a few operational checks you can try,dynamic braking etc.. If you look at the hydraulic schematic you can trace each circuit as to where you could be loosing that pressure. Deere writes a hell of a good manual as far as theory of operation goes. I don’t know your mechanical background but feel before you are done you will know everything there is to know about a 490e.Remember you are looking for horses not zebras.
Joe; Again thanks for the reply. I am a retired professional consulting engineer, land surveyor and general contractor. My father was a diesel and automotive mechanic with his own shop for his whole life, as was his father. I tore down and cleaned parts for his operation for many years. I have built multiple cars and airplanes as a hobby. Yesterday I sold my last car, a 1967 Cobra replica custom I built from the ground up to a collector in Florida. He said it was the best of the 60 he had in his collection. I was an assault helicopter pilot in Vietnam. I bought this excavator from a contractor I knew to dig a 15 acre lake on my property. I also have a JD front end loaded with three yard bucket and two other tractors. This hydraulic heat problem on this machine has cut my ass and apparently many other experienced mechanics as well. There has to be a solution and I intend to find it. I have a man working for me who has done a lot of the work on this machine to date. I have given him sections of the O & T manual to follow. Tomorrow I will go behind every setting, control valve, load sensing valve and relief valve to make the system as correct as I can get it. I have too much invested to back away now. I will let you know what I find and if I find it.
I started my mechanical career at dads gas station and got my HD red seal in 1981 in Alberta ,Canada.I worked in the oil patch for a bit and was lucky enough to be employed at dealerships (Cat,Case, and International)finishing up with 22 years as a field mechanic at Deere. I was asked to fill in for a teaching position at a local trades college for 3 months and ended up staying for 4 years full time.I retired a couple of years ago but I still teach part time .When I started teaching I thought how hard could it be.So far it’s been the hardest thing I have done but by far the most satisfying. One thing that I learned working for dealerships is that they don’t make machines one at a time.There are problems inherent with any design and the 490/790E had quite a few.You learned after a while the quickest way to diagnose a problem was to check the technical service bulletins and parts inventory to see how many parts had been sold for a particular machine. I still have some contacts that work for Deere and I will pick their brains to see if they have any solutions that relate to your overheating problem.This has got me damn curious and I am trying to think anything you missed.I might work up a case study for my students next time I teach hydraulics . You sound like you have had an interesting life and I admire your dogged determination.Most guys would have lit a match to this thing a long time ago. Keep me posted!
I would be more concerned with the reservoir temp than the swing motor . When the cooler temp was measured was the machine at full throttle with pumps at full flow ? Do you normally run the machine at full throttle ? Is there a hyd oil temp guage in the machine ? How is the engine temp ?
Volvo; The machine is normally run in service at full power. I have previously had the radiator boiled and rodded. I resealed with new foam between the hydraulic oil cooler, radiator and frame. The fan belt is good and tight. I initially believed the heat source was the engine, but when I lock the pilot system the machine temperature drops very quickly. There is not an independent hydraulic temperature gauge. The reported temps were measured immediately after the machine temp gauge hit red line. The machine has always had a tendency to run on the warmer side but recently began hitting the red line after a couple hours of operation. Yesterday I tested the pilot control solenoids electrically. They have already been removed, inspected and resealed. One propel solenoid was out of specification reading high at 65 ohms, the others read 24 to 25 ohms each (Spec is 10 -50), so I ordered a new solenoid and a new main pressure control valve. The old main pressure control valve would only screw in a third of a turn before bottoming out, so I thought maybe the spring in it had become weak. Today I am adjusting each of the good pilot solenoid circuits to obtain specified pressures on each. I will then reset all main pressure circuits to specifications. I have read in the manual the pilot control pressures are used by the PVC to adjust the main pump demand responses, particularly during combined usages, so they are being done first. Once the pilot circuits and the main circuits each meet pressure specifications, I will revisit the swing motor. When I cranked the machine yesterday to move it to my shop (while cold) the swing motor was whining but the swing reliefs were still full in.
No joy today on the pilot control pressure settings. I did not have the correct fittings. In my last post I made a mistake in identifying the pilot control solenoid which had failed. Instead of the propel, it was a swing brake solenoid, which leaves me with the question: Could the failure of the pilot control brake solenoid make the swing motor have to fight it? In other words, could the pilot control brake solenoid be positioned so as to make the swing motor have to work harder against it, hence creating the heat? I do not know how the brake solenoid system works, but if it is fighting the swing rotating motor, it could be the source of my problem. Any input from knowledgeable experience will be appreciated!
Today I installed the gauge for the swing pilot solenoid system pressure test. The results I got were puzzling to me. At I (idle), the pilot system had 440 PSI, at L still 440 PSI, at E it dropped to 230 PSI and at P to 200 PSI. The manual calls for the setting at P to be 427 PSI. Are these readings typical or is there something else going on? Should I proceed to attempt to set the swing pilot solenoid at 427 @ P?
I attempted to get the pilot control solenoid for the swing adjusted to 427 PSI @P. With the solenoid adjustment screw full in, the most I could get at P was 300 PSI. How should this failure to reach full adjustment of the swing pilot pressure be corrected? Should this fault be treated as a failure of the pilot control solenoid, the swing main control valve, or what? The pilot pressure regulator valve and pilot pressure relief valve previously tested good in pressure. Yesterday I had a round with my local JD dealer. The swing brake solenoid ordered arrived Thursday, and upon visual inspection it was not the swing brake solenoid for my machine, so I returned it. The second one arrived yesterday, passed visual inspection, but before installing it, I checked the ohm reading which was 62 ohms. My old one was 65 ohms, so both the old and the new were outside the 10 to 50 ohms specified by the manual. I called the dealer who said he would have to initiate a defective part claim. When he called back about 2 hours later, he said the solenoid I received was from Hitachi, although it was received in a John Deere Box with JD part number, and because it was an aftermarket part, it did not meet the John Deere manual resistance spec, but I should go ahead and install it. Mindful of the $450 just spent for the replacement valve and only 3 ohms different from the valve I had, I ask him how I was suppose to know if the solenoid I had was not previously replaced so as to not meet the JD spec? Then I ask if he would pay $450 for a valve having only 3 ohms difference, when the reason for ordering the replacement was the high ohm reading? He said he would call the factory again. Has anyone dealt with this issue before?
Did you take a reading of pilot pressure before you adjusted it up 80 psi? The reading you are getting at the solenoids comes from the pilot pressure reducing valve and if you change the main pilot pressure you change that as well.As for the resistance in the coils I would send the new coil back and go with the original.Every coil has some resistance and it will change with temperature. The parts guy you talked to may not realize that the machine is an Hitachi but painted yellow with a Deere engine.It is not an after market part!! As for the swing brake not releasing there is an operational test in the manual that will rule out problems with the swing.The swing motor will over power the swing brake and it should release whenever you use a pilot function. The problem with diagnosing a problem like this is that sometimes you lose sight of the forest because of all the trees.Also check your pilot pressure switches. They tell the PVC to release the swing brake.
Joe, you have been a stalwart adviser to me on this machine and I do sincerely appreciate it. This morning I was back in the manual and found the specific test for the swing brake solenoid on page 9015-10-84. The swing brake solenoid electrical specification is different than the other pilot control solenoids. The manual specification is 59.7 plus or minus 10 ohms, so the one I had and the new one are both in specification electrically. The flow chart said 10 to 50 Ohms on the plot control solenoids, all tested 24-25, so as you said, it is hard to see the forest for all the trees. The learning curve for me is steep on this machine. Progress on the program to reset and test everything has been delayed due to a flat tire and a hose replacement on my loader. The sheath on the main hydraulic hose on this ex was found separated with rusting wire underneath. Since the failure of that hose would have soon emptied the hydraulic reservoir, we got a new hose. The radius on the new hose ends were not equal to the original ones. The original ones are no longer available, so it caused routing problems and delays. My plan to methodically go through everything keeps getting delayed. If you would contact me at [email protected] , I have something to send you.
The overheating problem has been found and corrected. It was the pilot control system. Neither the regulating or reducing valve met pressure specifications, so they were replaced with new. In the process I blew the pilot return filter into 4 pieces. The regulating valve would not meet pressure specs (giving me 10 PSI for 0.010 shim, where the manual says it should be 20 PSI), so I kept increasing shims till the pressure regulation valve locked, blowing up the pilot filter housing. The main spring in the new valve was 3/8 inches longer than the old one. I suppose it failed due to heat and fatigue. Once the regulating valve was replaced, I found the reducing valve was in like condition. The individual pilot control solenoid adjustment screws are not pressure regulating valves as the manual indicates but rather pressure balancing valves and must be set while the controls are active. The manual is silent on this issue. Once the regulating valve and reducing valve pressures were to specs, the solenoids which had been resealed were re-balanced. Then we readjusted all the circuit relief valves to specifications. Operation is back to normal and the heat problem is gone. Since I read that dead heading of the pilot control pump could cut the head of the pilot pump, I replaced it as well. I do not know how the pilot pressures caused the PVC to increase flow, but it obviously did and blew that flow through the relief valves creating the heat. Along the way, two experienced mechanic's suggested that I sell the machine because I might not ever find the over heating problem. The control system is very complicated with multiple reliefs on every circuit, but I have too much invested in the machine to sell it without getting the work from it for which it was bought. This was a six month project, but I refused to let it beat me. Along the way I resealed and replaced many parts which were not defective, looking for the heat cause. I hope others can learn from my experiences.
@Knivens894 - Sounds like you need to make a trip down to Louisiana to give me a hand with my Hitachi EX120-2.
The problem can be solved, but it takes tenacity. I have been through about every system on this machine looking for the problem, started with having the radiator boiled and cleaned, resealed around the radiator and the oil cooler, removed the thermostat and checked it in a pot of water, it opened at specs. Pressure cleaned both radiator and hydraulic cooler externally. Been through the hydraulic oil cooling system, looking for some type of blockage at the valves, none found. The JD tech said it was the engine injector pump so I had it overhauled, no change. Then it was the swing brake, it was chattering at "L" so the manual said it was not releasing. Found the O-rings had scuff marks, resealed it and the chattering stopped. No excessive heat change. Checked the main relief pressure and reset it. No change. Checked the surge relief and reset it, no change. Checked the swing pressure control valves and reset them. No change. Checked the swing pump for excessive leakage, none found. When I got to the pilot pressure system, it was in shambles. Neither the pilot regulating valve nor the pilot pressure reducing valve were in pressure specs. I resealed the solenoids first, thinking that might be the problem, no change. I had to do that one twice because I did not read the manual and orient the sleeves properly so the ports discharged to the ports in the valve body. Resealing did not bring the pressure pilot pressure regulator or pilot pressure reducing valve into pressure specs. I increase the pilot regulator shims until I locked it trying to get the specified pressure and blew up the pilot filter body (4 pieces). Then I had to buy a new pilot pump because I read the dead heading of the pilot pump could cup the head of the pilot pump, causing up to a 40% loss in capacity. The main spring in the pilot regulator valve was bad. It was 3/8 inches less in length than the new valve. Once it was installed and set, I found the pilot pressure regulating valve was in a similar state, so I replaced it. Resealing the pilot control valves caused issues of their own. The manual says the valves should be adjusted for pressure, but is silent on how that should be done. Some said it was static controls, I tried that, with no joy. Then I learned the pilot solenoid adjustments were not pressure control valves, but rather pressure balancing valves and must be set with controls dynamic. Basically the pilot control regulating and reducing valves set the pressures for that system. The individual solenoids are adjustable to balance that circuit's solenoid system. Go too far one way, it reduces the pressure the other way. They are intended to be balanced. An unbalanced solenoid will cause the auto idle to stop functioning. I have studied the hydraulic system diagrams and do not understand why the pilot control pressure being low would cause the PVC to call for more flow, but it does. The excess flow from the main pump blows through the reliefs causing heat. Once we got the pilot control system adjusted, we moved on to the individual system relief valve adjustments. The end result was the problem was solved. I had two mechanics tell me to sell it, because I might never find the problem. That is BS because it is mechanical and electrical. I refuse to let a machine beat me. It took me six months and more parts than I call recall, but the machine is working better than today than since I have owned it.
Congratulations, and thanks for the final outcome. It's always appreciated.
Ditto, not many people would have spent that much time and money finding and fixing the problem.
I am a brand new member on this site because I am hard-headed and like to figure things out myself but I got to tell you this information you just gave me has been so helpful I have done basically all the same things that you have done on my 1998 Hitachi 200-3.. computers, wiring harness, DP sensor, angle sensor and a constant hissing from the hydraulic cooling pipes.. I have not pinpointed the issue but in this post when you mentioned the pilot control system that's where all the heat seems to be coming from mine right at the solenoid valve Bank with the directional valves and the proportional valves. I am going to look into the power system tomorrow morning!
Do you think the spring tension has something to do with the reducing valve for the pilot system and the pressure valve? I wish I had the measurements for those Springs I have been looking on forums on my specific machine never thought the look at the John Deere 490 so happy I found this forum and thread I have been at least four months messing with this machine
Welcome to HEF Eric ! Beautiful area there in Southwest Harbor. I rented a place once in Tremont. Loved it there. Maybe start a new thread of your own rather than piggybacking off this one.
The more we know, the more we know we do not know. I had the machine working great, no stalling and no overheating, then it went south AGAIN. I have found that the exposure to oil and hydraulic fluid leaches the elasticizers out of the PVC insulation on the wire conductors. As a result, the insulation cracks and spalls off of the conductors. Older machines have been through repeated baths of hydraulic fluid as a result of hoses popping. On the machine I have it will now have to be rewired. I confirmed this using a megger meter. (high voltage, very low current). Disconnect the computers and check the insulation of the wires to ground. I have many wires that have completely failed and others which were severely compromised. Now in the process of completely rewiring the machine, and that is a tedious job.
It is a very nice spot grow up here up my whole life! I apologize I've never joined a forum group new at this I don't even know how to start my own thread!!
I appreciate the information so much I have the solenoid valve Bank off right now I'm in the process of cleaning it I have replaced the outer wiring harness with a new PVC and engine control computer I found two wires backwards in the new harness that went to the to high-speed solenoids the blue with red stripe wire was backwards with a solid yellow wire now I am kind of skeptical on the rest of the wiring harness whether I should trust everything is pinned out correctly♂️
Or, better still ................ HeavyEquipmentForums
Thank you!!
Thank you for the information i appreciate it!!