Backhoe jw03 no pressure

[ultraken08]

new to forum and owning a tractor!!! please be gentle.

I bought this jinma 200 with a what i believe is a jw-03 backhoe on it about a month ago. The backhoe ran slow when I got so I checked the fluid and it was really white which told me that it had water in it. I changed it out with aw 32 oil and it ran good for about a week then started to get slow and jerky.

Istarted to clean the press. relief valve by pulling off the bottom part only and cleaning it. after putting the bottom back on it still didn't work so i drove it around using the fel. after about 20min. the pump was screaming hot.

At this point I let cool down over night looked the internet at pics and took the prv all the way apart and put it back togeather. still nothing at the backhoe for controls. drove it around and the pump didn't get hot.

went out today to mess with it and still nothing. put a press. gauge have 0 press.. looked in the oil tank and it was half empty can see the filter, oil is white looking again? filled the tank up turned the prv and still nothing!!

can any one help please!!

 

[erj]

Let us see if we can figure out what you have.
1. Is there a nameplate on the backhoe? It is usually located on the 'box' that contains the control valve.
2. If it is a JW03, it should have its own hydraulic tank located under that same control box. Does it?
3. The JW03 usually have their own hydraulic pump. It connects to the PTO auxilary shaft that is located above the PTO shaft that sticks out of the back of the tractor. Is this what yours is like?
4. You say the pump gets hot. Is that the tractor pump or the backhoe pump?
5. How did you hook up the pressure gauge?
RonJ

 

[ultraken08]

haven't looked close at the plate but yes seperate tank,seperate pump mounted above pto, only got really hot once(boiling hot i would say). pressure gauge was mounted directly above prv where the cap can be removed with flat head driver.

 

[SPIKER]

If it is a JW03 there should be a breather about between your feet when you are standing on it.

the pump and tank are all self contained if there is fluid going someplace there must be a leak. the leak is usually down under the valve in a pretty hard to see area. I have not heard of the pump seals blowing on these like the JM main hyd pump when a QD pops apart accidentally or deliberately when removing the FEL.

The JW03 are also bad for breaking HYD cylinders at the Lift Arm, (usually breaking off a rod end.) I have broken 2 so far on mine while digging on rocks under ground. Look for breather foam meaning you are sucking air and foaming the fluid up and out the vent or fill point. The Pressure Control in them also has had some issues as you are finding out. sticking relief valves as well as broken springs./

Mark

 

[ultraken08]

can only find one tag and it is on control blocks. it doesn't say jw 03.

all it has on it is:

34DLS-3 10 L. Y-
16mpa 40L/min

 

[erj]

can only find one tag and it is on control blocks. it doesn't say jw 03.

all it has on it is:

34DLS-3 10 L. Y-
16mpa 40L/min

OK that is the number info for the Control Block itself.
Ron

 

[erj]

OK let's get started.

I think that the first thing that we should concentrate on is the PRV valve and lack of pressure. You said that you had that valve apart and I wonder if perhaps it went back together correctly.

Send me a PM with your Email address. I will send you a PDF file showing the disassembly, etc. of the PRV. Also just in case, I will send you a file showing the mounting of the pressure valve on the PRV.

While you are waiting, Mark made a good point - that hydraulic tank has to breathe. Mine has a separate breather filter, but most don't. Check to see how yours breathes. On most of them the bolt that holds the dipstick has a hole drilled in the side and bottom of the bolt head. If you have this type, see if air will blow through it.
RonJ

 

[ultraken08]

replaced o-ring on inlet to prv line at box also the one on prv cap on top. same problem!

Took pump off and took it apart found that the W or E gasket are missed up and pieces missing!!

going to order a rebuild kit!!

 

[Diamondpilot]

I have a feeling you have a restriction coming out of the pump. I would take off the hose and check it for debris.

Chris

 

[RonMar]

Or you had a restriction going into the pump from the old imulsified oil making pase on the tank strainer/filter.

Hydraulic pumps are great at making pressure, but they really suck at suction...

The pumps are cooled by the fluid that passes thru them. A pump gets hot for 2 reasons typically.
1. It is making a LOT of pressure.
2. It dosn't have any fluid flowing thru it to cool it.

So you took the PRV apart, I don't believe that would have any effect on an overheated pump, untill you tried to operate the BH, as the valve block is open centered, and the fluid will just flow right thru it untill you work a lever and send fluid to a cylinder.

A pump outlet restriction could cause the pump to overheat, but what is going to cause it that would survive a passage thru the pump, and still be large enough to stop up the main passage?

So I would say pull the tank filter assembly and see what is up with that...

The first thing I would do if I were in your position, when I get the pump back together would be to disconnect the hose that runs from pump to valve block, at the valve block and run it to the tank fill port, or a bucket. Then start up the tractor with the pump running to insure you have good flow thru the pump. If you run it into a measured bucket, you can check the pump output volume with a stopwatch using the output per revolution label on the pump... If you have good flow that way, then you can reconnect it to the valve block, and disconnect the return line to the tank and run it into a bucket and insure you have flow thru the valve block. You can also test the passagway thru the valve block by disconnecting the tank return line and putting it in a bucket and shooting compressed air into the pump output. This should squirt air and fluid out the return line to the tank.

 

[ultraken08]

put new o-rings in prv cleaned and installed. put pump back togeather and installed. every thing works great except the boom coming back up. I have to wait a little bit then go up then wait etc.

haven't put pressure gauge on to adjust because I am waiting to figure out how to adapt it to the prv.

 

[Rich Waugh]

That slow boom, when everything else is okay, makes me think you might have a hose or a port partially blocked. The boom cylinder is the biggest one, so any decrease in volume of flow would affect it the most, I think.

 

[erj]

Here is a copy of the Email that I sent Kenny on Sat after I had sent the PDF files mentioned earlier in this threadl
Kenny,
My suggestions of what to do while waiting for the pump rebuild kit:
1.Did you check out the breathing method for the hydraulic tank?
2.I believe that you said there was still white fluid in the tank. I had that problem a couple of years ago. It took a couple of tank refills to get rid of it. I suggest that you remove and clean the filter that is in the tank.
[And since that gives you an access hole, I would run a magnet around in there to see if you get much metal shavings. You also could consider dumping in some kerosene to sort of swab it out. (suggestions only-probably not necessary(]
3.Disconnect the pressure hydraulic line between the pump and the PRV and blow it out. This should get rid of any pump seal particles that may have gotten in there.
4.Since you ran the pump with the bad seals after you rebuilt the PRV, I would consider rechecking that PRV valve to be sure no crud got in there.
Did you get the specs for the adapter for the pressure gauge? Do you have the other needed parts? That adapter and concept for it was developed by RonMar who hasn稚 been on this site for awhile. He lives in Port Angeles if I remember correctly. Attached is a copy of the instructions that he sent out a few years ago when he made up kits for several of us JW03 owners.

When these are done, the pump rebuilt and the pressure gauge installed then the pressure can be set on the PRV. I suspect that is the problem, but if that is set without these other things taken care of it could just crud up again.
RonJ

RonMar-welcome back, haven't seen your name here for awhile.

 

[RonMar]

Hey Ron, I sneek back in every now and then

UltraKen08, you might want to read thru the below linked thread. I learned quite a few things when I put in a return line filter on my BH. If your pump is making noise in operation, you will want to possibly look in to reconfiguring the return line to the tank, particularly that banjo fiting right at the tank. My pump has been quiet ever since I did this, as it should be, just like the main hydraulic pump on the tractor...

http://www.tractorbynet.com/forums/chinese-tractors/111225-jinma-hw03-backhoe-return-filter.html

 

[ultraken08]

Thanks Ron I'll look in to the filter for sure!

Got my pump rebuild kit today and installed it!

cleaned filter,blew out lines etc.

hooked pressure gauge up and let her roll!!

every thing worked, but I'm only getting 1500psi before the prv kicks in is that right? It's pretty much turned all the way in!

went out and used it seems to be working but fluid is coming out of my breather cap and vent on my dip stick any thoughts?

Thanks, Kenny

 

[RonMar]

Thanks Ron I'll look in to the filter for sure!
every thing worked, but I'm only getting 1500psi before the prv kicks in is that right? It's pretty much turned all the way in!

went out and used it seems to be working but fluid is coming out of my breather cap and vent on my dip stick any thoughts?

Thanks, Kenny

Kenny, if I recall correctly, it should be 16MPA, which works out to I believe around 2250PSI. You may still have some issue with the PRV not seating properly, or the pump is now only capable of outputting 1500 psi. The hot run may have caused some internal wear

How much fluid is comming out of the breather? If the tank is filled to the point that the bottom of the filler neck is suibmerged, and the dipstick/vent is not venting properly, when it gets warm, the air trapped on top of the fluid will push the fluid up the filler neck and out the vents in the cap. mine did this. Try removing the dipstick completely and see what happens... I ultimately did away with the dipstick and added a small inline automotive filter as an air filter, on a piece of rubber hose pushed down over the dipstick port(found it more usefull as a vent than a dipstick). I then sealed the ports in the filler cap. If I want to see how much fluid is in the tank, I unscrewed the filler cap and looked down the filler neck

The return line filter mod is a good thing. the importer I got my BH from said the only real problem they ever really had with these hoes was caused by crud in the oil interferring with the PRV. The main issue with the return line into the tank however is that it ends in a banjo bolt that has a small center bore. That small bore returns the fluid to the tank like a straight stream fire hose nozzle. It shoots right across the top of the tank as a high velocity jet and drags a lot of air into the oil as it enters violently. Shoot a straight stream garden hose nozzle into a bucket and you will see what I am talking about. if you open up that port so the fluid enters the tank more gently, it dosn't drag any air down into the fluid and the pump dosn't wind up ingesting a bunch of air. It is really bad for a hydro pump to pass tiny air bubbles. The pressure change makes them act just like sand, and it causes cavitation and pump wear... Depending on how that fitting is welded into the tank, that could also be why you are leaking oil out the top. If it is spraying against the filler tube, it may be splattering hard enough to find it's way up the filler neck...

 

[ultraken08]

Tomorrow I'll check the prv again and look into the venting again. I like the Idea of sealing that off and with a filter.
I did notice when I had the cap and filler strainer off the return line shoots the fluid right at the filter to the pump!! Something I will have to take care of.
The pump to my visual eye looked very good inside, but I'm finding it doesn't take much to make a head ache.

Thanks again, Kenny

 

[RonMar]

Tomorrow I'll check the prv again and look into the venting again. I like the Idea of sealing that off and with a filter.
I did notice when I had the cap and filler strainer off the return line shoots the fluid right at the filter to the pump!! Something I will have to take care of.
The pump to my visual eye looked very good inside, but I'm finding it doesn't take much to make a head ache.

Thanks again, Kenny

Oh, and 16 MPa converts to 2320 PSI... I looked back at an earlier post when I first fitted the gauge adapter and disassembled my PRV. I set mine for 2300 PSI. I need to put my gauge back on, as I havn't checked it for a while. Since I reconfigured my control cabinet and plumbing(tank is now mounted vertical between my knees), I think I have a safe place to permanently mount a gauge...