Got another wee intermittent fault on my '96 dash 3 ex200 which I would be grateful for any advice on; The machine tracks along perfect from cold start up and under light operating conditions, each of the 3 tracking speeds function correctly, tracks run at same speed, tracking power is normal etc - all good. However, when digging/working hard and the hydraulic oil gets really hot, and you go to re-position the machine, sometimes the tracking goes dead slow, ie slower than the tortoise speed. Pulling the boom up simultaneously, or another arm function, tends to cure the fault, ie she will be tracking dead slow, you boom up, and suddenly she's off again at normal speed. Both tracks are affected identically, it occurs irrespective of which speed mode is set, and she tracks straight and true whilst affected and otherwise. The oil cooler is newish and the oil doesn't seem to be getting too hot. Someone suggested the oil might be bypassing a bad seal in the rotary manifold (or it could have a crack) once really hot and returning to tank, because this is one of the only elements of the two track systems which is common to both sides? Any and all bright ideas would be very welcome indeed, cheers in advance. Nb, you can also buy her if you like! http://www.argyllauctions.co.uk/product/20-ton-hitachi-excavator/
Sounds like a priority valve (if it has one) or maybe the stroke control for pump? Not familiar with a Hitachi but if pulling the boom function kicks it in don't think problem could be anything after the control valves.
A leaking seal in the rotary joint can cause your issue.If you have a service manual,look to see if the arm function oil is next to the travel oil flow,as it goes through the joint.A cross leak there will do strange things.
When you activte a front function while traveling, it activates the flow combiner valve. Normal travel circuit is ine pump dedicated to each track. So when you use a front function it shifts one pump to both tracks and allows one pump to supply the circuit selected. Why is the hydraulic oil getting hot and how do you know it is hot ? What is the oil temp running at ?
Thanks for the responses so far - the hydraulic oil isn't getting excessively hot, but it does get hotter the harder you work her - as with all machines I have used (my komatsu has a hyd oil temp gauge). The problem only manifests itself when the hyd oil is at 'full' hot operating temp, not when you are just tinkering around with her. Cheers
The dash 3 does not have a flow combiner valve (dash 1 did).The dash 1 was a bullet proof machine and easy to diagnose as it had 2 separate pumps with 2 separate swash plates.The dash 3 was the first to come out with a computer controlled system and they really had their heads up their butts when they designed it.It has 2 pumps but only one swash plate and has closed centre valves .There are 7 double check valves that control the load sense system (load sense tells the pump to start pumping when you use a function)They take the highest work port pressure and send load sense oil to the differential pressure sensor which tells the computer to tell the pump solenoids to put the pumps into stroke.The one most important check valve is # 7 which separates the propel from the dig.If it gets stuck then you won't have any load sense oil going to the DPS from the propel side and the pump will not pump.It is located on the hyd control Valve side closest to the engine between the 2 main pressure ports coming from the pump.There is a tin panel you can take off beside the engine which makes it easier to get at .It is a plug and check valve.It is about the easiest thing to check.Is the swing slow as well?
Joeblow - cheers for the good advice, this makes sense to me and although I'm inexperienced, it does feel more like a control/pump/flow issue, rather than a case of gradually increasing oil pressure loss from a leaking/cracked rotary manifold. My reasoning for this is that the fault is either 'on' or 'off' - ie it doesn't get progressively worse/slower, the tracking is either perfect speed, or dead slow (something suddenly sticking when the hyd oil is fully hot). From memory the swing is not slow as well at the same time - will check this. Would that reinforce your thinking that check valve 7 might be at fault? Someone locally I spoke to suggested that, based on a previous experience on a similar -3 machine, the pump solenoids are not telling the pump to spool up - which could presumably be caused by the sticking check valve 7 as you describe? Any further thoughts gratefully received - prior to bracing myself for a round of £35/hr fitter charges fault finding...!
hey scottish 35 pounds is dirt cheap for a field mechanic where i am from. To save yourself a lot of money it would be wise to invest in a service manual.Deere writes a great manual for that machine (790e operations and tests) which explains the system with colour schematics ,theory of operations etc.Then go find a mechanic that can read a hydraulic schematic.For the cost of a manual (they are not cheap) it will save you thousands in diagnostic time.You have no chance of repairing something without first knowing how it works. The dash 2 was a grey market machine and the dash 3 got hitachi competitive with everyone else that was producing an electronically controlled excavator. They were a steep learning curve for us old guys that were used to the old hydraulic systems.First thing to remember is not to let the smoke out of the box (computer )Don't use a test light,only use a high impedance multimeter. Then find out if your problem is electrical or hydraulic .I have repaired many machines by just repairing a bad connection or a ground. Your problem does sound like that check valve because when the propel does work it does not misstrack.That is the only thing downstream that is common to both sides. The rotary manifold problem will effect either one side or the other. Good Luck
£35 would be real cheap.....if he ever fixed anything! Bear in mind that's $56/hr in your money - what's the going rate in Victoria/BC? I hear you re a service manual - will check with HM Plant (hitachi's uk parts subsidiary), in the past they've adopted a confused silence whenever an EX model prefix is mentioned... Is there a simple way to test the check valve #7 or determine whether it's functioning correctly? Cheers for all advice
Labor rates around here run in the $110/$115 range plus drive time, plus mileage, plus, plus, plus!
Hey scottish I found a manual on amazon for $475 US ( like I said,they aren't cheap)but it works out to about 4 hrs labour plus travel for some poor mechanic to stand there and guess. Grab a set of spanners and just pop the check valve out and look at it.
Thanks for the schematic Joeblow - your help is really appreciated. Will pull that valve between the two pump inlets and take a look and report back asap. $110/hr ~ $1000/day? Why isn't everyone a mechanic out there??!!
Why isn't everyone a mechanic out there? I could give you a list. I personally like a good puzzle.
Its the mechanic to parts cost curve.. More you spend on the mechanic, less you waste on unneeded parts.. At least thats how its supposed to work. You can find "mechanics" from $18 an hr up to 100+. Trick is finding the right guy for the right job..
thakyou
Hi all, Was just browsing and saw this thread become active again - update - I never did cure the dash3 gremlins on this machine, although it never actually stopped her working for me, and I ended up getting a lot of use out of the machine. She is now (I assume) still plugging away on a job site in Pakistan. Sold for £10k last year at roughly 16k hours to an exporter who told me she went in a container the following week (I paid £14k for her, plus prob £6k in maintenance and breakdowns), so I'm pretty happy with that for 5 yrs work... I have fond memories despite all the problems and all subsequent machines being much more trouble free (so far). Thanks to all for valuable advice here
yeh got the urge to have a look at the hitachi again thought i had it halve working pulled num 7 check valve that improved it alot still wasnt quite on the money so i pulled the other check valves cleaned them now its hopless again i cant understand how anything whith 6000 hrs on cant work again icouldnt give it away so ill just have to keep wasting time on it any tips would be gratefull apreicated thanks wabco
how did the check valves look when you pulled them and I cannot remember if you can swap them but if you can try that. Also look at the harness for the differential pressure sensor. You can swap the pump solenoids as well. Are you getting any codes?
yep its been awhile since i had given up on it last time so i got to start again we rplaced the wiring and solienions it was getting their then something i have done has made it worse i moved the angle sensor i now got it back in the shed so ill have to put some gauges on and start reading again how to set the angle sensor set thanks wabco
no codes idont think the lights just seem to flash to gether
the check valves were all tight to get out after i freed num7 it seem to work better still wasnt quite their so i pulled the others which were tight then that made it worse thaen istarted carrying on sily and altered the agle sensor then give up
bit of a discovery the hose that runs from the pressure reducing valve on the solenoid valve assembly to the main control bank when it is blocked of the machine seems to respond i had it blocked before i did the check valves when i put it back on the machine wont respond if iblock it it sort of works
Ah Yes the pump angle sensor. If you can make a break out connector on the harness to the angle sensor or just bare the wires ( black and red with yellow stripe) and put a volt meter on them you can set up the sensor.Start by switching the connectors between the 2 pump solenoids one for the other.This will put the pumps into full swash.You can just disconnect the 2 connectors and it will eventually go to full swash but this way is quicker.Then loosen the 2 allen head screws on the sensor until they are just snug.Turn they angle sensor until your volt meter reading says 4.5 volts then tighten the bolts and recheck.It may change the volt reading so fiddle with it until you can get exactly 4.5 volts.Reconnect the 2 pump solenoids and you are done. You can also set the pilot pressure up 100 psi from spec and it will make the hydraulics a little more responsive. Do not lose hope .These dash 3s can be frustrating as hell but when they work good they really work good.
Do the above PAS adjustment with the machine running at idle.
more trouble joe blow i hadnt pulled check valve out of auxzillary valve num 6 when i did i only got halve out do you think i could put it back to gether and leave it in thankyou for response the hose that runs from the control bank to top of pilot pressure reducing valve i put a gauge in it nothing on pilot side but 500 to 2000 psi when you take a function to end of stroke out of control bank does that sound right thanks wabco
if # 6 check valve sticks then it will dump load sense oil to tank .Sounds like you may have found the problem.
thankyou thankyou joeblow for pionting me in the right track iam all keen to try it again but cant get num 6 slug out hitachi isnt my main gig so i can only attack it when i get the urge i had just about given up till isaw your post hoping to be able to keep in touch thanks wabco
joe blow got the check valves out all pretty tight and dry i think ill have to chek them again i some times think iam getting closer to fixing this little devil what ihave noticed is when ever the pump destrokes if you hold your hand on the pilot pressure line it feels like it unloads then at the same time the solieniond works same when you pull on the lever and it up strokes you can feel it in the lever when it unloads you see the solioniond light flash do you think i shoud check the pressure in the accumulator on the pilot just trying to think which way to make my next move thanks wabco
Kindly give information on how to get this service manual written by Deere, appreciate your response.
I need a service manual that can guide on Fiat-Hitachi FH200E-3 control valve spools installation and arrangement.