Hitachi EX200-3 pump noise

[scottish]

Hi Guys,

Any info/suggestions on this problem would be hugely appreciated - if you can view/copy and paste the links below you should get to two youtube videos of my EX200 pump at idle;

http://www.youtube.com/watch?v=wL3Y74JS8Bs

http://www.youtube.com/watch?v=QXjIYnx6Zfo

What the heck is that intermittent rattling noise? It's been a feature for the whole of my ownership (2 years ish) but is now getting more frequent/slightly louder and I am concerned for the pump failing. She still has plenty power and is tight despite high hours. The noise seems to be related to the small steel hose which goes from a plate on top of the pump (just above the 2 solenoids) to a tee into the pressure side of the pilot pump hose leading to the valve block......what does this steel hose do?? Is it related to the solenoid(s)? The noise can be clearly 'felt' when putting your hand on this steel hose, and can be detected in the pilot hose leading up to the valve block. The pump solenoids also seem to get pretty hot - too hot to keep your thumb on for longer than a second or two... What do these solenoids do? (apologies for my blatant ignorance...)

At certain working revs the rattle is still there and can be felt through the controls/machine in general, but it seems to be becoming more prevalent throughout the rev range... Cavitation?

Any help/advice would be really appreciated - an accurate (and cheap to fix!) diagnosis wins you the $$$$ equivalent of a nice xmas hamper!!!

Cheers

 

[pfpm]

The diagnose bit is easy, The clicking noise is the high speed solenoids on top of the pump firing. They become prevalent especially at idle when they fire to keep the pump at minimum stroke, you probably find that as the machine warms up they do it more often. I think that as the pump wears the slider is more inclined to "fall" on stroke so the electronic system is forced to re position the slider, hence the clicking sound.
You can swap the 2 solenoid around and see if that helps but make sure you don't swap the wiring or the pump will go to full stroke.
I notice that they fire more than once at a time which could mean other faults with the electrical system eg angle sensor.
Others may have more experience than myself.

Regard Mike

 

[scottish]

Hi Mike,

Thanks for the info - it makes sense to me, based on my limited knowledge of this machine's hydraulic system... The fault deels like a control issue rather than major wear/failure in progress - my local mechanic wants to just pull off the pump and send it away to be reconditioned, but I'm reluctant to go for the 'major surgery' option until I've eliminated lesser possibilities such as the sensors/solenoids, as she can still dig hard.

Is there a way to test if the solenoids are functioning as they should? (one was replaced a while back with a chinese repro part to try to fix slow functions/pump bogging down, which seemed to work at the time). I have not had the angle sensor off yet (have read various threads here and slightly confused as to exactly how to check correct voltage/position/if it's working right or not). I replaced the DP sensor (chinese again...) at the time of trying to fix the slow hydraulics issue. I'm in a bit over my head to be honest and really need the advice of someone who knows these old EX machines inside out (such a person seems now to be non-existent here in Scotland, with everyone except me seemingly able to afford to run shiny new metal!).

Any further pointers/advice would be highly valued.

Cheers,

Charlie

 

[pfpm]

You can verify that the solenoids are causing the noise by disconnecting the wires. The pump will slowly come on stroke and load up the motor. I would still swap the solenoids around and see what happens( but not the wires)
If you want some peace of mind you can pull the pump head off and have a look at the pumping elements especially the valve plate and look for wear on the slider. This will give you a idea of the mechanical condition of the pump. This can be done with the pump still on the excavator. You can have a look at the angle sensor by marking where the adjustment slot is before you remove the screws. Take note of the position of the dot on the spindle, Check that the spring clip that goes between the A sensor and the pump is still in one piece.

 

[scottish]

Thanks v much Mike - very helpful info. If my mechanic is available I am going to get stuck into her today and see what's what.....fingers crossed. Will report back findings and hopefully have a plan of attack to fix her.

Cheers, Charlie

 

[mclean]

Our ex120 does the same thing.. Clicking and pulsing on the pilot pressure line, ive only ever noticed it at an idle when inspecting the machine. Interested to hear any news.

 

[scottish]

Still working on this - will report back when I have a definitive answer, but one source is now telling me this is normal - just the solenoids firing to keep the pump on stream... Not sure at all, but it could possibly be related to a worn/weal pilot pump too.

More pressing is to fix the latest fault in this saga - the 5 amp EC Motor fuse keeps blowing now! I can rev up with a bit of string on the throttle linkage, but the computer puts the hydraulics in limp mode...so once again all work halts. I am wondering if it could be the EC motor potentiometer, bad wiring or the motor itself has gone bad.

This machine certainly keeps me guessing and poor....

 

[rgl726]

you have a short circuit on the throttle motor and high speed solenoid wiring bundle on the pump room area.

 

[mclean]

Is there a limp mode? Our machine starts up seems to run pretty well then as it heats up it becomes very slow. I've swapped the wires on the solenoids and the machine is quick but tries to kill the engine when loaded..

Can the computer put it in limp mode or did the po put the limp pin in the shuttle?

 

[jaytech]

sounds like the angle sensor

 

[scottish]

Has anyone got experience of the 'manual regulator' kits? I am very tempted to go down this road, as I'm sick of electrical gremlins...

 

[scottish]

Bought the kit - fitting on Tuesday..........

 

[mclean]

Which kit did you buy? Hitachi or China? If its the Hitachi kit what's the part no.

I'm excited to hear how it works. I need to make the same decision..

 

[scottish]

Not sure if it's '100%' Hitachi, but it's certainly not Chinese - I purchased from O'meara Parts in Ireland. Comes with pretty comprehensive fitting instructions etc but I've not unpacked the kit as yet.

Will post back how I get on and whether it performs as billed - god how I hope so! If so I can put you onto O'meara; they dispatched the kit very efficiently and seem to have a very good knowledge of EX machines

 

[scottish]

Quick update; kit went on pretty easily with no major hitches...but, we couldn't get the machine to run well despite trying various shim combinations on both sides of the plug stopper. Power was fine but speed was well down compared to electronic control, ie about 35% of it's old self. Not fast enough to dig, and problems of boom not going up simultaneously with stick in (ie you end up just digging deeper and deeper rather than grading). Other shim combo's had the pump loaded at idle and engine smoking. Annoying as the kit has great promise but with a possible 3 shims on each side of the stopper and therefore a very large number of possible combinations of shim set up, along with the fact that it's not that easy to swap in and out and try each combo (some hyd oil loss each time) it seems very hard to get bang on. If only the instructions had a paragraph along the lines 'add shims top to increase x, add shims below to increase y' etc but no detailed explan of what/how the kit works. I'm sure cleverer people than me could have it worked out in no time, but after two days I have given up and am back to electronic control. Having found three pump loom wires shorting whilst she was torn down and fixed these this seemed to help with the original problem of solenoids firing excessively and EC motor fuse now is intact. BUT, after an hour hard running this am she suddenly died down, pump loaded, engine smoking - left her to cool 3 hrs and bang away she goes again good as gold - must be a solenoid breaking down once hyd oil gets right hot??? Gonna change today and see whats what......the joys. Anyone want to buy a manual regulator kit for a Hitachi EX 120/200/220 ??!

On the plus side I bought a Komatsu PC160 this am so might actually get some work done when it arrives.

 

[rankothge]

hello scottish,
is your machine OK? I have such as a experience of ex120-5. is your problem solve with replacing pump solenoids? thanks

amalka

 

[joeblow]

These dash three machines came out in 91 and were the first with electronic pump control and throttle.As with anything that has a wire in it connections are key.as for the two solenoids on top of the pump,one destrokes the pump and the other puts it into stroke(starts it pumping)It sounds as if one of the solenoids is cutting out thus putting the pump into full stroke and lugging the engine.The rattle you hear is simply the pilot relief going off and all of the dash 3s make the same noise.As the pump sits under the muffler the wiring gets pretty crispy and as the temp increases so does the resistance.You could take the time and make a new harness and replace the solenoids and it may get rid of a lot of your grief.DO NOT mess with the pump angle sensor unless you know what you are doing.You can tap into the harness to the pump angle sensor with a volt meter with the positive going to the red/yellow wire and the neg to the black.Dis connect the 2 solenoids at idle and wait about 5 minutes .(this should put the pump into full stroke)You should read 4.5 volts DC .If not,loosen the 2 allen head bolts on the angle sensor and turn it until you get 4.5DCV.Tighten the bolts and watch the voltage change(thats how sensitive it is) Keep fiddling with it until you get the voltage right. Also be aware of the pin on the bottom of the load piston( small plate on bottom of pump)If you get that thing out of place then you will have only 65% of your pump capacity(35% of its old self?)
Dont loose heart.If you have a Deere dealership near you go and find the oldest mechanic they have and buy him a beer.Hitachi made most all of Deeres excavators since 1989 and he may have a service manual.

 

[scottish]

Joeblow, cheers for the advice, I changed the solenoid for an old one I had lying around and she's been working away fine of late, though not on anything too hardcore. The only fault of late has been that when the hyd oil gets really hot, the tracking intermittently goes really slow - I suspect something sticking at the valve bank, as if you activate the boom at the same time she speeds up again.

I've also got her up for sale if anyone in Scotland is watching!!!

http://www.argyllauctions.co.uk/product/20-ton-hitachi-excavator/

Although she's a good strong machine I am not electro-mechanically minded enough to have the patience to keep at her, and will pass onto someone who will. I like driving (ie breaking) them, not fixing them!

 

[scottish]

Ps. On a different issue, my slew ring gear grease cavity (accessed from the inspection plate in the tool box step) fills up with water all the time on this machine. I was climbing a steep bank yesterday and it was p*ssing water out - how is this supposed to drain? I've pumped it out before greasing the ring gears in the past, but it just fills up again and can't be doing the slew ring bearing any good...

I was thinking of drilling a hole in the lower inspection plate accessed from above the belly plate (which is missing on my machine) to let water drain out, but presumably the grease will drain out too if the hole is big enough not to choke up?

Am i missing something here? Cheers for any advice

 

[joeblow]

Ps. On a different issue, my slew ring gear grease cavity (accessed from the inspection plate in the tool box step) fills up with water all the time on this machine. I was climbing a steep bank yesterday and it was p*ssing water out - how is this supposed to drain? I've pumped it out before greasing the ring gears in the past, but it just fills up again and can't be doing the slew ring bearing any good...

I was thinking of drilling a hole in the lower inspection plate accessed from above the belly plate (which is missing on my machine) to let water drain out, but presumably the grease will drain out too if the hole is big enough not to choke up?

Am i missing something here? Cheers for any advice

There is a rubber boot under the rotary manifold that seals the cavity from above.If it is torn or out of place(ithe boot should slip over a flange on the mount)It is a bit of a bitch to get it back on but if you clean out that area and clear the drain holes under the boom cylinders then water should not collect in that cavity.