490 E Hydraulic problem -Help Please

[Andre-1]

if thats the case check your pilot pump pssure. at least it should be 700 psi with a very little pressure flactuation when you are giving pilot command.

the pump pressure i deceiving you mush monitor it when giving pilot command.

weak pilot pump would result to poor combined operation

I checked the pilot pressure and I got 500 PSI on the bucket pilot cap, also same for swing pilot cap, I read from the manual that it should be at least 740 PSI, this would be the regulated pressure from the regulating valve. At some point while curling the bucket the pressure would be zero and when it curled to an extent it shot up to 500, and sometimes fell to zero.

I got 250 PSI on the pressure reducing valve and I read it should be 512 PSI +/- 15 PSI. does this say i need a new pump?

I didnt test the pressure directly at the pilot pump outlet because i dont have the fittings for that connector. Do you think the pump is bad and what would be the damage?

 

[rgl726]

try to find the correct fitting so you can check directly on the pilot pump.

if you have lower reading than specification try to adjust first the pilot pressure relief valve.

if you cannot increase the pressure with the relief valve you need a new pump.

 

[willie59]

I can't address your pressure adjustments, but there should be a filter in the line that leaves pilot pump and goes to regulating valve/relief valve manifold. Removing that filter cartridge and checking for metal debris/fragments should give you a good indication of condition of pump. It's a gear pump, and if it goes down, there's going to be some metal in that filter.

 

[Andre-1]

try to find the correct fitting so you can check directly on the pilot pump.

if you have lower reading than specification try to adjust first the pilot pressure relief valve.

if you cannot increase the pressure with the relief valve you need a new pump.

thanks for the reply I put more shims in the pressure reducing valve and got pressure somwhere around 500 psi. now the hammer no longer slows down and combined function seems better. More adjustment is needed though so I will continue to test and adjust.

If a valve in series with the pump is leaking wouldn't that cause me to get a low pressure reading at the pump outlet since it cannot build pressure? Wouldn't I have to used a load valve/ flow control device to check pump pressure where I can adjust the load on the valve and check the corresponding pressure the pump produces?

 

[Andre-1]

I can't address your pressure adjustments, but there should be a filter in the line that leaves pilot pump and goes to regulating valve/relief valve manifold. Removing that filter cartridge and checking for metal debris/fragments should give you a good indication of condition of pump. It's a gear pump, and if it goes down, there's going to be some metal in that filter.

thanks for the reply I put more shims in the pressure reducing valve and got pressure somwhere around 500 psi. now the hammer no longer slows down and combined function seems better. More adjustment is needed though so I will continue to test and adjust.


I am going to chk for fragments as you suggest.

 

[Isuru]

Mr 3doc, can i have workshop manual of EX 120 -3 please??cheers!

 

[MEARS]

3DOC- I have read tons of your posts and you seem extremely knowledgeable on these machines!! Can you please point me in the right direction.
I am working on a Hitachi EX200 LC-2, the engine stalls or dies if function is held. I have read through tons of articles looking for the answer..
Right now I have correct voltage going to my DP Sensor, but when doing the DP Sensor Voltage test the lowest I can adjust t is 0.8v, (I have the old type sensor with the jam nut and Allen adjust screw) the book says it should be (0.4 +0.15 -0.1v) but sometimes the machine runs fine when you unplug one of the Pump Displacement Solenoid Valves, so I OHM tested both of them and came up with 16.8 - 17.1 ohms of resistance the book says (15.5v +- 1.0v). After all that I tested the Angle Sensor, removed it checked everything and the lowest I can adjust it is 4.87v the book says normal range is (4.40v +- 0.03v).
So with all that I think I have two bad Pump Displacement Solenoid Valves, a bad Angle Sensor, and possibly a bad DP Sensor.
Where do I go from here? I don't really think all 4 items are bad but I guess it's possible.
My email is MEARS_Mechanics@hotmail.com or wherever is best for you to help me.