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Hitachi EX200-3 weird tracking fault

scottish

Active Member
Joined
Jan 21, 2013
Messages
33
Location
scotland
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/
 

Shimmy1

Senior Member
Joined
Aug 14, 2014
Messages
4,260
Location
North Dakota
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.
 

Outasite

Well-Known Member
Joined
Nov 10, 2013
Messages
185
Location
Mi
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.
 

GregD1

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Joined
Oct 6, 2013
Messages
221
Location
Tonopah, Az.
Occupation
Equipment for a paving contractor
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 ?
 

scottish

Active Member
Joined
Jan 21, 2013
Messages
33
Location
scotland
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
 

joeblow

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Joined
Jan 13, 2013
Messages
238
Location
Victoria B.C.
Occupation
Retired
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?
 

scottish

Active Member
Joined
Jan 21, 2013
Messages
33
Location
scotland
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...!
 

joeblow

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Jan 13, 2013
Messages
238
Location
Victoria B.C.
Occupation
Retired
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
 

scottish

Active Member
Joined
Jan 21, 2013
Messages
33
Location
scotland
£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
 

Outasite

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Joined
Nov 10, 2013
Messages
185
Location
Mi
Labor rates around here run in the $110/$115 range plus drive time, plus mileage, plus, plus, plus!
 

joeblow

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Jan 13, 2013
Messages
238
Location
Victoria B.C.
Occupation
Retired
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.
 

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scottish

Active Member
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Jan 21, 2013
Messages
33
Location
scotland
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??!!
 

joeblow

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Jan 13, 2013
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Victoria B.C.
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Retired
Why isn't everyone a mechanic out there? I could give you a list. I personally like a good puzzle.
 

mclean

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Joined
Mar 13, 2013
Messages
63
Location
Beautiful Washington
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..
 

wabco

Active Member
Joined
Aug 26, 2013
Messages
27
Location
australia
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.
thakyou
 

scottish

Active Member
Joined
Jan 21, 2013
Messages
33
Location
scotland
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
 

wabco

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Aug 26, 2013
Messages
27
Location
australia
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
 

joeblow

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Jan 13, 2013
Messages
238
Location
Victoria B.C.
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Retired
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?
 

wabco

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Aug 26, 2013
Messages
27
Location
australia
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
 

wabco

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Aug 26, 2013
Messages
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Location
australia
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
 
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