1996 John Deere 490e excavator hydraulic problem

[dbags89]

I am helping a friend of mine work on his excavator. I will try to explain what is happening the best I can. When you boom up with out the rpm's up it will work fine but when you turn up the rpm's the boom will work really slow and you also can hear some kind of noise coming from the area of the control valve. The noise sounds like something is bypassing. We don't have any books to help out. So maybe somebody can help us. Thanks

 

[tool_king]

Sound like you have relief valve stuck open, a spool valve hung upor a pilot problem.I will email some info to you.What is your email address?
Thanks
ED

 

[dbags89]

dbagwell89@yahoo.com
Thanks Ed

 

[tool_king]

Check your email .I sent you over manuals .

 

[dbags89]

Got them thanks. Will let you know what happens. Thanks again

 

[dbags89]

Hey tool king would a bad pressure reducing valve or a pilot pressure regulating valve cause the boom up to be slow or if they were bad would all the functions be slow not just one
Thanks Donnie

 

[tool_king]

Donnie dumb question the hydrualic tank has the right amount of oil in right.I am just reading the out the the manual for a 120 - 160 machine. I know checked it but sometimes the simple things get over looked. You know your suction screen in the hydrualic tank and pilot filter could be clogged up .These would slow things down alot.If you are going the check suction screen in hydrualic tank it might be a good idea to swing machine so tank is between tracks and drain into open clean drum .Then you look into tank and see if debri is stuck to suction screen .Because if you pull screen with oil in tank the oil may wash off debri as you pull it upif it is light .You might the problem .I have found all kinds of things in tanks .Not just hydrualic tanks mostly fuel tanks.It would blow your mind.If you need help call me at 1-201-832-1606 .I will try and help you over the phone if I can.
Thanks
Ed

 

[dbags89]

So it needs a hydraulic filter but we had a leak in the cover of the variable pressure compensator valves when I got the cover off it has a bad o ring but I also noticed that two middle valves where stuck in. So I took them out one by one and cleaned them when I put them back in they still seemed to stick the other two moved freely and when you push in on them they did not stick. So I am wondering if that could be a problem.
Thanks Donnie

 

[shopguy]

Does the auto idle function work on the boom? Did you check the pilot pressure switches?

 

[dbags89]

I don't know on the first one and no on the second

 

[tool_king]

dbags89
I if you have a sticking spool it mess things up for sure .Are the spools from the ones that move easy the same size as the stuck ones .Use the good ones to check the spool block.You could have a bent spool or warpped block sction .I had that on a jcb wheel loader.Call me at 1-201-832-1606 if you need help. I can help you on the phone may eplain it better.

 

[shopguy]

I don't know on the first one and no on the second

The pilot pressure switch tells the pvc when you pull a lever,, it tells the solenoid bank what to do with the vpcv,the auto idle is just a quick way to check the switches

 

[Andre-1]

Check your email .I sent you over manuals .

Toolking do you know where i can get an EPC (engine)controller for the JD490E for a good price? In the US

 

[joeblow]

Try swapping the circuit reliefs on the boom section top to bottom and see if your problem changes

 

[jjfarms]

I have a 490e was traveling extremely slow (like barley moving) , finally found a stuck spool in a solenoid valve , you can test that with a gauge on the pilot line for the proper function that is not working correctly , mine had 800 lbs psi at idle and was supposed to have 398 at full travel.

 

[Dwallace]

I have 490E has a slow stick only. if you surge or bounce the boom it will take off and move. works intermittently some times. I can hear something bypassing in main valve until stick goes. seems a bit weak in and out. Everything else about the machine works fine. in need of some service manuals.
thanks, Daniel

 

[joeblow]

sounds like a bad connection to the arm pilot pressure switch which is in the flow regulator valve behind the cab and under the tin plate (tool box where you keep your grease, bucket teeth ,big rocks that you found) There are actually 4 pressure switches under there .The arm in pressure switch is on the other side of the valve you are facing. Swap that out for the pressure switch on the other side(boom raise ps) and see if your problem changes.

 

[mg2361]

Welcome to HEF Dwallace! Might I suggest the next time to start a new Post rather than piggy backing off an old one.

 

[Dwallace]

sounds like a bad connection to the arm pilot pressure switch which is in the flow regulator valve behind the cab and under the tin plate (tool box where you keep your grease, bucket teeth ,big rocks that you found) There are actually 4 pressure switches under there .The arm in pressure switch is on the other side of the valve you are facing. Swap that out for the pressure switch on the other side(boom raise ps) and see if your problem changes.

ok, I swapped the (ps) from first valve closest to door too the back valve. made no difference in how the machine functioned. unpluged all (ps)s. still no difference.
seems the machine will function if there is pressure against the boom. run the stick out until weight of bucket is on it. then it takes off and goes on out every time. bring it back in gravity at speed too the bottom then wait for it very slow until pressure against boom. bam takes off power and speed.

 

[Dwallace]

ok, I swapped the (ps) from first valve closest to door too the back valve. made no difference in how the machine functioned. unpluged all (ps)s. still no difference.
seems the machine will function if there is pressure against the boom. run the stick out until weight of bucket is on it. then it takes off and goes on out every time. bring it back in gravity at speed too the bottom then wait for it very slow until pressure against boom. bam takes off power and speed.

could variable pressure compensator valves be the problem?