• Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

Boom down randomly becomes weak when warmed up - John Deere 490e excavator

fastline

Senior Member
Joined
Aug 8, 2011
Messages
1,110
Location
OK
Seems like a weird design to me but apparently the pilot switches tell the system that certain functions are happening and I guess they are supposed to upstroke? I am getting lost in this repair but the basics usually prevail. Many people term 'lack of power as 'lack of speed'. Remember these hydro pumps are pos displacement so not being able to develop force is different than just going slow. Slow usually means lack of fluid volume (lack of stroke), vs lack of power which could mean bad pumps or valves leaking over so PSI seen at implement is not at spec.

At this point, simple pressure gauges might tell you more. I know it has proven things to me more than once, which you can then write off! In the repair field, finding what is 'right' is usually part of sourcing the issue.

Also remember that boom up and stick out require big girl power from the engine and pumps. Boom/stick down usually uses recirc valving to reduce useless system demand, heat, etc.

Let me put this more simply. If you are doing a boom up, if you tap in the line, if the boom pressure can go to relief pressure at full ext, that means valves could be working fine. If they are way short, that is an issue to address first. If relief is good but speed is slow, you need to find a way to ensure pump stroke is at max. If it is, pump has an issue. If it isn't resolve why pump is not going to max stroke.
 

joelx777

Well-Known Member
Joined
Apr 1, 2022
Messages
169
Location
Washington State
Seems like a weird design to me but apparently the pilot switches tell the system that certain functions are happening and I guess they are supposed to upstroke? I am getting lost in this repair but the basics usually prevail. Many people term 'lack of power as 'lack of speed'. Remember these hydro pumps are pos displacement so not being able to develop force is different than just going slow. Slow usually means lack of fluid volume (lack of stroke), vs lack of power which could mean bad pumps or valves leaking over so PSI seen at implement is not at spec.

At this point, simple pressure gauges might tell you more. I know it has proven things to me more than once, which you can then write off! In the repair field, finding what is 'right' is usually part of sourcing the issue.

Also remember that boom up and stick out require big girl power from the engine and pumps. Boom/stick down usually uses recirc valving to reduce useless system demand, heat, etc.

Let me put this more simply. If you are doing a boom up, if you tap in the line, if the boom pressure can go to relief pressure at full ext, that means valves could be working fine. If they are way short, that is an issue to address first. If relief is good but speed is slow, you need to find a way to ensure pump stroke is at max. If it is, pump has an issue. If it isn't resolve why pump is not going to max stroke.
Thank you Fastline. This is not a loss of speed, boom down goes quickly enough. However, when I press the bucket on the ground to lift the tracks, nothing happens. When the problem occurs, pressing the bucket down exerts no power or force, or at least not enough to lift the tracks.

I agree completely that it is time for some pressure gauges. I actually have worked on taking a hydraulics course online for around 30 hours, so I know the basic principles... but I have never done any actual hands on work and don't own any gauges. What size pressure gauges and hoses and fittings do I need? Is there an easy way to find this?
 

fastline

Senior Member
Joined
Aug 8, 2011
Messages
1,110
Location
OK
Thank you Fastline. This is not a loss of speed, boom down goes quickly enough. However, when I press the bucket on the ground to lift the tracks, nothing happens. When the problem occurs, pressing the bucket down exerts no power or force, or at least not enough to lift the tracks.

I agree completely that it is time for some pressure gauges. I actually have worked on taking a hydraulics course online for around 30 hours, so I know the basic principles... but I have never done any actual hands on work and don't own any gauges. What size pressure gauges and hoses and fittings do I need? Is there an easy way to find this?
What you have to realize is what I said previous, when the boom or stick goes down, 'usually' there is a recirculation valve or a 'counter balance valve' that creates a short circuit if you will. Allows oil to simply flow from one end of the cylinder, over to the other using only the weight of the machine.

At the exact point where you strike the ground, that valve should slam shut and allow the pump to take over feeding that circuit with high pressure.

That valve is where I would start. I can't imagine there being an electric switch for this. Usually all mechanical, either inside the big valve block or by itself.

If there literally is no power to pick up the machine, that means oil is leak by in the system. It could be that valve, a bad relief valve, etc.
 

joelx777

Well-Known Member
Joined
Apr 1, 2022
Messages
169
Location
Washington State
What you have to realize is what I said previous, when the boom or stick goes down, 'usually' there is a recirculation valve or a 'counter balance valve' that creates a short circuit if you will. Allows oil to simply flow from one end of the cylinder, over to the other using only the weight of the machine.

At the exact point where you strike the ground, that valve should slam shut and allow the pump to take over feeding that circuit with high pressure.

That valve is where I would start. I can't imagine there being an electric switch for this. Usually all mechanical, either inside the big valve block or by itself.

If there literally is no power to pick up the machine, that means oil is leak by in the system. It could be that valve, a bad relief valve, etc.
I think you are right, I will test the hydraulics, especially the relief valves now. The system and surge pressure relief valves have to be tested prior to the circuit / cylinder relief valves according the manual, so I am going to do that first.

It's been raining like crazy here, so I haven't gone out yet to do anything further with the machine. I did price out some of the fittings to try to test pressures on the machine from Pape. All of these are tee fittings from the manual...

Tees:
$48 JT03191 (7/16-20 M 37° x 7/16-20 F 37° x 7/16-20 M 37°) Tee (Propel Speed Change Solenoid Valve Test & Adjustment)
$153 JT03464 (1/4 BSPP M x 7/16-20 M 37° x M14-1.5 M 45°) Tee (Propel Proportional Solenoid Valve Test And Adjustment)
$16 203836 (9/16-18 M 37° x 9/16-18 F 37° Sw x 7/16-20 M 37°) Tee (Pilot Pressure Regulating Valve Test And Adjustment)
$17.64 202862 (3/4-16 M 37° x 3/4-16 F 37° Sw x 7/16-20 M 37°) Tee (Oil Cooler Flow & Pressure Drop Test)

$15 TH108328 - 4200465 adapter System Relief Valve Test And Adjustment, Surge Relief Valve Test And Adjustment-Serial, Circuit Relief Valve Test And Adjustment, Swing Motor Crossover Relief Valve Test

$997 JT05984 Flow Meter 0-400 L/min (0-100 gpm).... I will probably skip this unless I have to have it...

Hoses / pressure gauges / fittings?

I also found this cheaper Chinese kits online... You think one of these could do the job or should I buy the individual parts from Pape above?
-https://www.amazon.com/SINOCMP-Hydraulic-Kit-Pressure-Gauges/dp/B07TQD53FT#customerReviews
-https://www.amazon.com/VEVOR-Hydrau...d0-837b-70aea8607210&pd_rd_i=B09Z6NQDCV&psc=1
-https://www.amazon.com/dp/B0833WS6D...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=
-https://www.amazon.com/CO-Z-Hydraul...bd3-a0f4-59b3eeb0e177&pd_rd_i=B087TVQH99&th=1

Any opinions on if I should buy this stuff or something else?
 

fastline

Senior Member
Joined
Aug 8, 2011
Messages
1,110
Location
OK
What I might do is study the hydro schematic carefully. I don't know how many pumps you have but use other machine functions just to verify the pumps can achieve the spec pressure. Then you can be assured that part is good. Then move to boom down while in the air and as it touches down.

Has the boom down function ever worked correctly? Or is the issue sporadic? Is it only the boom down or other functions?
 

joelx777

Well-Known Member
Joined
Apr 1, 2022
Messages
169
Location
Washington State
What I might do is study the hydro schematic carefully. I don't know how many pumps you have but use other machine functions just to verify the pumps can achieve the spec pressure. Then you can be assured that part is good. Then move to boom down while in the air and as it touches down.

Has the boom down function ever worked correctly? Or is the issue sporadic? Is it only the boom down or other functions?
I have been reading and re-reading the manual to try to wrap my head around it. I believe there is just the main pump and a pilot pump on my machine. Good idea on using functions to make sure the pumps can achieve the spec pressure.

I believe the boom down worked correctly when I first bought it. I did a bunch of land clearing on my property and used the boom down to swing back and forth a lot to smooth things out, which I have since heard is not good to do and can cause issues.

The boom down pressing on dirt weakness issue is sporadic. It doesn't happen when the machine is cold, but does happen after 20-30 minutes of operation where I am pressing down with the flat of the bucket to lift the tracks. It does seem to still dig fine though, which is weird. I noticed it primarily after having backfilled a ditch when I am dragging with the bottom "knuckle" of the bucket to flatten things out a bit.
 

fastline

Senior Member
Joined
Aug 8, 2011
Messages
1,110
Location
OK
Aggressive side swiping can destroy the pins/bushings/arm, but I tend to think we all do some of that. I know I do but I am very careful to go slow and only do it for final finishing. That aside, it should not hurt the hydraulics of the machine.

If the boom is up and turned off, does the boom stay up or bleed down?
 

joelx777

Well-Known Member
Joined
Apr 1, 2022
Messages
169
Location
Washington State
Aggressive side swiping can destroy the pins/bushings/arm, but I tend to think we all do some of that. I know I do but I am very careful to go slow and only do it for final finishing. That aside, it should not hurt the hydraulics of the machine.

If the boom is up and turned off, does the boom stay up or bleed down?
The boom stays up and does not bleed down.
 

joelx777

Well-Known Member
Joined
Apr 1, 2022
Messages
169
Location
Washington State
joelx777 said
“Maybe someone replaced my controller with one for a 25000+ machine?”
.
There should be a part number on the existing PVC .
Screenshot with PVC part #’s below.
.
View attachment 295294
The mystery deepens... I see the part number 9116790 on my PVC, indicating this would be the correct version for my machine : pre-25000 serial numbers.

1000004771.png

The port where a boom up pilot pressure sensor would go appears to have some sort of flush plug in it. See below:

1000004703.jpg
And here is the parts diagram again for ease of reference:
1000004721.png
The million dollar question is why does my pre-25000 serial John Deere 490e Pump and Valve Controller expect a boom up pilot pressure sensor when that was supposed to be a post -25000 serial number feature only? And should I do anything like try adding one and running wiring for it, or just ignore this fault code?
 

fastline

Senior Member
Joined
Aug 8, 2011
Messages
1,110
Location
OK
Inclined to ignore and keep testing hydraulics. Check books to find which pins on controller for that sensor and see if it is even pinned out. If no pins in the connector, just move on for now. It was workout without before.
 

joelx777

Well-Known Member
Joined
Apr 1, 2022
Messages
169
Location
Washington State
Here is a demonstration of the issue and a test suggested by a friend to see if operating the bucket would help the boom (it did not).

https://photos.app.goo.gl/m8oT2h8YhjVk5gSF9

When the weak boom issue occurs, it appears to not be helped by opening the bucket, so it looks like it isn't the shuttle valve of the variable pressure compensating valves. I do hear a little extra noise that I think could be a relief valve letting hydraulic fluid through prematurely. The bucket operates with regular power unlike the boom.

I still am looking for suggestions on pressure gauges if anyone has them for testing this and identifying exactly what the cause is.

Thank you for your help!

Joel
 

joelx777

Well-Known Member
Joined
Apr 1, 2022
Messages
169
Location
Washington State
Inclined to ignore and keep testing hydraulics. Check books to find which pins on controller for that sensor and see if it is even pinned out. If no pins in the connector, just move on for now. It was workout without before.
Sounds good.

Here are my new test gauges in a kit I bought for $175.

1000004869.jpg

1000004868.jpg

1000004867.jpg
 

fastline

Senior Member
Joined
Aug 8, 2011
Messages
1,110
Location
OK
Here is a demonstration of the issue and a test suggested by a friend to see if operating the bucket would help the boom (it did not).

https://photos.app.goo.gl/m8oT2h8YhjVk5gSF9

When the weak boom issue occurs, it appears to not be helped by opening the bucket, so it looks like it isn't the shuttle valve of the variable pressure compensating valves. I do hear a little extra noise that I think could be a relief valve letting hydraulic fluid through prematurely. The bucket operates with regular power unlike the boom.

I still am looking for suggestions on pressure gauges if anyone has them for testing this and identifying exactly what the cause is.

Thank you for your help!

Joel
Have no idea what I am hearing, but when you push down with the boom, there seems to be an odd swooshing sound which could be a failing valve. I recommend you get extra ears on it to investigate. I do know how microphones can pickup noise that isn't really there too.

I don't think there is any question that what you will see if boom down pressure that spikes, but certainly not high enough. The question becomes where is the issue!

Now I am going to tell you a very sneaky way potentially spot this. A FLIR camera! If oil is going over relief, a bad valve, or even hydro cylinders are junk, you are going to find serious heating. You can set the machine on boom down for several seconds and get to feeling. Most people don't have a FLIR camera. You might not be able to spot he valve but it's return line will get hot.
 

joelx777

Well-Known Member
Joined
Apr 1, 2022
Messages
169
Location
Washington State
Have no idea what I am hearing, but when you push down with the boom, there seems to be an odd swooshing sound which could be a failing valve. I recommend you get extra ears on it to investigate. I do know how microphones can pickup noise that isn't really there too.

I don't think there is any question that what you will see if boom down pressure that spikes, but certainly not high enough. The question becomes where is the issue!

Now I am going to tell you a very sneaky way potentially spot this. A FLIR camera! If oil is going over relief, a bad valve, or even hydro cylinders are junk, you are going to find serious heating. You can set the machine on boom down for several seconds and get to feeling. Most people don't have a FLIR camera. You might not be able to spot he valve but it's return line will get hot.
I wish I had access to one of those FLIR cameras! My laser temperature thermometer gauge might be sort of similar? Much less efficient though.

I did receive my pressure test set in the mail, and I was able to hook up my 10,000 PSI gauge to the system test port on the pump. I was seeing 5100 to 5200 PSI at the max, which is what the surge and circuit relief valves are supposed to be set to approximately according to the manual. Is there an easy way to test each of these separately? I am guessing they are probably fine since it's only the boom down function that's an issue.

Not much visible in this video, but it shows the machine was too cold for testing. And since the machine was cold, the boom down function was working. https://photos.app.goo.gl/2rx8KXHPM8jvH4T36

I think the most likely culprit is the boom down pressure relief valve malfunctioning. I am going to try to tighten it's set screw tomorrow after I get the weak boom down misbehavior to happen again and see if that fixes it.
 
Top