Backhoe Jinma 354 backhoe hydraulic problem

[crofutt]

The backhoe on my 354 developed an odd problem suddenly the other day. As I was taking the last "bite" of digging a very long ditch the boom would raise very slow and actually I have to help it to get it all the way up. Plenty of power in the down motion, just the up. I switched the hydraulic lines and of course the lever was reversed but same problem. I think it points to the cylinder but before I yank it off and send it somewhere I thought I would ask to see if anyone else had a similar issue. Thanks!
Bill

 

[RonMar]

I think your suspicions are correct and that it could have a seal torn on the piston. The boom lift is probably the most stressed as it is lifting the structure and whatever is in the bucket. The same action having the problem with the hoses reversed pretty much confirms that it is in that cylinder. Hot fluid after a long workout could also be making ths problem more evident.

I would also reccomend that you check your relief pressure. Since this particular cylinder is under so much stress, an over pressure condition from the valve could also have shortened the piston seals life and could ultimatly damage other components.

Good luck.

 

[crofutt]

Thanks Ron, I had the cylinder repaired locally a couple years ago after the welded-on pressure line sprung a leak. Maybe it was something they did/didn't do but they charged 250 or 300 bucks which I thought was a lot. I am leaning towards a new cylinder. Anybody know where I can get one?
Bill

 

[Bob Rooks]

The newer cup seals are opaque and stronger, not black rubber. I had the same problem on boom & jib cylinders. The Chinese rubber does NOT like synthetic hydraulic oil.

If you get a new cylinder, expect the same seal longevity unless it has the new style seals in it.

I solved the whole problem and went with the LiTW hoe. Nice and smooth.

 

[SPIKER]

You may also be able to switch the boom up cyl to the bucket curl cyl. I've had to do this to fix broken rod ends, (swapped them around made new rod ends then welded them on using the boom (elbow position) as a welding jig. I haven't had any seal issues but have broken 2 rod ends, (waiting for the 3rd one to break now lol have a NEW rod end waiting for it already home made ones work great vs the factory cheap cast ones...)

mine is JW03 though so may be different than yours...

mark

 

[crofutt]

I started this thread one year ago. I had the cylinder rebuilt (500 bucks this time) and finally installed it today. It pretty much does the same thing it did before..... no power. But now it seems to be affecting other cylinders too. The bucket curl, and both boom cylinders don't have any power. The side to side and the out riggers seems to be fine. What the heck? Any ideas anyone? Fluid is full and clean. I thought maybe it was sucking air but the oil doesn't seem to be foaming or bubbly. Thanks

 

[erj]

Which backhoe do you have? Does it have it's own pump or run off the tractor hydraulics? What does a pressure gauge read when it is hooked to the backhoe?
RonJ

 

[crofutt]

ERJ,
It's a 2005 JW-03 mounted to a 354. The pump is mounted on rear of tractor. I don't have a pressure gauge. I overfilled the tank yesterday afternoon to where the oil level was into the filler neck. I was hoping this would show any bubbles in the oil better and sure enough there are a lot. I have no idea if this is normal or not. It's a little tough getting a good picture inside the filler neck but even in this one you can see the bubbles. BTW, new NAPA hydraulic fluid. And after more checking, all cylinders running off the backhoe pump have reduce power. The outriggers won't lift tractor off the ground now. Thanks for any help. Bill

 

[RonMar]

ERJ,
It's a 2005 JW-03 mounted to a 354. The pump is mounted on rear of tractor. I don't have a pressure gauge. I overfilled the tank yesterday afternoon to where the oil level was into the filler neck. I was hoping this would show any bubbles in the oil better and sure enough there are a lot. I have no idea if this is normal or not. It's a little tough getting a good picture inside the filler neck but even in this one you can see the bubbles. BTW, new NAPA hydraulic fluid. And after more checking, all cylinders running off the backhoe pump have reduce power. The outriggers won't lift tractor off the ground now. Thanks for any help. Bill

Well I would say you are not getting to full pressure. Air in the system can partially cause this. But a safety relief with crud in it, or that is set incorrectly can also cause this. One source for air would be the supply line from resovoir to pump. IF this is loose, or has a bad seal/O-ring in one of the O-ring face seals(ORFS), the pump could be sucking air along with fluid. The JW-03 by design will induce it's own air. The return line to the tank probably goes thru a banjo fitting on yours? If you take out the bolt and look at the hole down the center of the bolt, you will probably find that it is around 1/4". Ths causes the fluid to re-enter the tank in a high speed straight stream. This high speed stream shoots into the fluid in the tank at high velocity and mixes in air. It also shoots right across the top of the tank, and this whole air filled mess rolls down to the intake strainer to be drawn into the pump. Go try and fill a water bucket with a high velocity straight stream garden hose nozzle and you will see what I mean. When I was troubleshooting my BH filter installation, I saw pressure spikes as high as perhaps 100PSI on that return line caused by that restriction into the tank, so a garden hose into a bucket will give you a good idea what is happening. A sign of air intrusion is the pump making noise. Does your pump have a squeeling noise to it, that gets louder as you put it under load/work the BH controls? If so, you probably have air in the supply fluid. That pump should be as quiet as the main pump up on the tractor engine. My pump made noise untill I fixed the high velocity return into the tank. I just described that here, and the gentelman I described it to also shows how he did the same thing.
http://www.tractorbynet.com/forums/chinese-tractors/143897-backhoe-first-time-3.html

Probably the easiest way to check the oil pressure and where the safety relief is set is to sample one of the working ports on the valve. Do you have a hydraulic shop around? Most I have seen have metric adapters. The JW-03 hoe uses hoses with ORFS connections. The valve however has straight metric threaded outputs. The manufacturer uses metric to ORFS adapters comming out of the valve body to attach the hoses. I think You need a 18MM X 1.5MM to female NPT adapter and a hydraulic pressure gauge good to at least 3000PSI. Take one of your ORFS adapters along to make sure you get the right size. Put the gauge into the adapters NPT end. On the valve identify a port that feeds a particular cylinder, so you know exactly what lever to move to send fluid to that hose. Disconnect that hose and put the hose end in a bucket(don't loose the O-ring). Remove the metric-ORFS adapter from the valve port, and screw in your adapter and gauge to that port. With safety glasses on in case there is a leak, start up the tractor and engage the PTO/backhoe pump. With everything up to speed, work the lever that will send fluid to the port that you put the gauge into. If you get it backward, the cylinder will move and fluid will flow into the bucket If you get it right, nothing will move but the needle on the gauge. The pressure you see on the gauge is the pessure that the safety relief on the BH valve is relieving at...

 

[crofutt]

Thanks Ronmar,

The darn thing worked great until I sprung a leak in the cylinder giving me the grief now, had it rebuilt and worked fine. Started doing what it's doing now, had it rebuilt again and it didn't fix it. I took the relief valve apart and it was clean. I cranked the pressure up 3 turns just to see if it changed anything and it didn't. (reset it afterwards). I have too many projects and really don't have the time for this along with everything else. Will call the cylinder people tomorrow and see what they say. Thanks for your advice, it is much appreciated and I'll post what eventually is the solution so others won't have to do everything I have.

Bill