TC45 Hydraulic leak down

[arljbuilding]

I am by no means an expert in tractor mechanics nor hydraulics and seek the ability to learn within these forums by what I have perceived to be many well educated members here.

I have an 06 TC45 16LA loader and 758 backhoe, all hydraulics leak down when left over night including my outriggers. I obviously can lock them in to avoid this issue. I have noticed what I believe to be a significant loss in hydraulic power both within the drive train as well as the implements. I changed all filters and new fluid when I purchased the machine and have replaced the front pump by diagnosis of dealership that it was bad and not producing proper pressures. I am not so certain now that that was the real problem. Machine had 700 +/- hrs when purchased and now at around 1300 +/- hrs so little hours per say.

I believe that I have a relief valve possibly partially stuck open somewhere causing the pressure/power loss, I have isolated the backhoe by detaching and reconnecting the three point hydraulics and still get leak on the front bucket. When both bucket and backhoe are attached everything leaks down.I am also aware if the valve beneath the seat and have that tighten down all the way for full power.

My interpretation of the power loss and not just being used to the machine and trying to overwork is this, 1800 to 2000 rpm optimal engine speed the machine does not have the power in both outriggers to lift itself nor can I push a pile of dirt and bog the engine to a stall or break the tires free.

Can someone help me along here with a starting point and share any similar problems that may help diagnose the problems, I do not feel confident sending the machine back to the shop at a cost that scares me after the last trip. I have all the manuals and have begun to dig in and learn more but I am very much a hands on mechanic and don't really cherish the reading side to much.

Thanks so much for any input,

Tony

 

[jinman]

Hello Tony and :welcome: to TBN. All you have to do is look at my post count and you can tell I'm not the shy type. I'll try to help.

Your overnight leakdown is pretty common and has very little (none really) to do with the system performance. Some of these tractors have leakdown when brand new. Others commonly develop it over several hundred hours. It is considered minor in most cases, especially if it does not interfere with operation. By that I mean if your outriggers would not hold the tractor without your feathering the valve, that would be a problem, a BIG one. However, if every few minutes you have to touch up their position, it's not a big deal, I have to do that on my full-size TLB also.

Also, the valve under your seat has nothing to do with power. It is simply an adjustment of how fast the 3PH drops when your move the position control lever downward. It adjusts how fast the fluid leaves the 3PH cylinder when you move the lever down. Since the 3PH doesn't have downpressure, it just drops from the weight of the implement. A heavy rotary cutter will drop faster than a lightweight plow. You can adjust that valve to make them drop at similar speeds or to make your arms go down faster when you have nothing attached. Again, the valve has nothing to do with power.

Now one thing you said concerns me. The fact that your tractor won't lift the outriggers at 1800-2000 rpm sounds like a possible problem, but will it lift fine if you go to 2500 rpm? Why do you say that 2000 is optimal engine speed? Is that in your Operator's Manual? I would think 2500 - 2600 rpm is optimal if I am going to get full power and flow from my hydraulics. In addition, hydraulic power and the strength of the HST transmission for getting power to the ground is NOT associated. The HST power is limited by an internal relief valve that is set for 5000 PSI on your tractor. The HST system is completely isolated from the main hydraulic system and has its own pumps. The only common thing is it draws fluid from the same reservoir as the main pump. Both pumps pull fluid through the main hydraulic filter between the running gear and the right rear wheel. If that filter is clogged, both systems will be starved for fluid.

I'm not an expert on the valves or pressure regulation of your 758 backhoe, but you indicate that it has degraded power with nothing changed. I know it is easy to get used to something and then it seems to be weaker. The only certain way to check the hydraulic system is to do a pressure-flow test. As a user, the flow test is difficult, but many of us have bought a 5000 PSI pressure gage and attached a male quick connect to it. That way we can install it into a remote quick connect fitting and monitor the pressure. I don't know if you have a convenient spot on your backhoe, but if you purchase a male quick connect that fits the loader quick connects, then you can plumb this to your gage. Just hook it into any of the loader quick connect fittings and use your joystick to pressurize that line with the engine rpm above 2000. Your hydraulic pressure should be 2500 PSI.

Your dealer has that gage tool and also the ability to measure flow. If your relief pressure is off, he will add shims to the relief valve to bring the pressure back to normal. Don't assume it will be a big expense. If your pressure is a low by as little as 200 PSI, you will feel it. It should not be a big deal to get it adjusted. If the flow is off, it might indicate pump wear and they will be able to tell you that too.

 

[LoneCowboy]

On my high quality (sarcasm) TC45, we had a similar problem develop over the first 900 hours.
turns out the internal cylinder to lift the 3 point had completely come apart (we thought just the seal had gone back, after taking it apart the whole thing had come apart)

that's my bet.

 

[arljbuilding]

Thanks so much for the info guys, I will start my journey running some of the pressure tests. I read in a post back some time ago when I purchased the machine that 1800 to 2000 rpm was optimal for operation, I find also anything over that the machine is screaming.

I failed to mention in my previous post that I get some hydraulic whine on start up especially during cold months, live in the Northeast.

Look forward to resolving issue as I feel the machine has way more power than I am experiencing right now.

Thanks again and I will keep all posted on progress..

Tony

 

[Pfloyd#1]

Hellow all,
I am having the same issue and I am pulling my hair out. I also have a TC45A with a 16la loader and 758C backhoe with 510 on hours meter. At the recommendation of a local NH dealer I replaced the main pump due to only having 500PSI at the diverter valve? In order to not contaminate or damage the new pump I drained and blew out all the oil from the lines and bleed all the cylinders to remove any perceived containments, and changed the hydraulic oil and filter. Giddy to have all back together and chomping at the bit to get some work done this weekend I started it at 9:30 Saturday night only to still have 500PSI: :mur:
I found this post last night (this morning) at 1AM, so I did some more research and thought that maybe it might be the pressure relief valve in the diverter. I added some washers to it to see if it would make a difference. Nope!
Any ideas?

Thanks for the help.

 

[wdchyd]

Pfloyd......Welcome to TBN.....

You should have read Jinmans reply regarding using flow/pressure testing as the NH dealer should not have given that advice unless unless it fails that test.....

Trying to fix hydraulics without the proper diagnostic equipment many times turns into a blind shuffle of swap outs till the trouble finally goes away....

Kubota Flow/Load Meter Test - Tractor Videos - Kubota, John Deere, New Holland and More

Of course if you have plenty of money, time and live on the dark side of the moon this wouldn't matter right..??

 

[J_J]

First, as other have said, test the pressure . I believe I would install a hyd gage at the input to the FEL, and leave it there for monitoring and trouble shooting, or you can install female 1/4 QD's at significant points around the tractor, and just plug in when you want to know.

If you think your system, is weak, you need to check the PRV for the specified pressure. You should not hear a relief whine unless the system is experiencing a load somewhere in the system. You get the whine when something is blocking the flow. If the pressure is good, and the bucket is weak, could be worn piston seals. A good cyl will make the relief whine at the end of the stroke. A weak cyl, may or may not cause the relief to go off, depending on the leak. One weak or bad cyl can cause loss of power, as you can not develop the power designed into the pump and cyl.

You could make your self a test load that equals the capacity of your bucket and use it to check out the hyd whenever, but a hyd gage is your best tool for trouble shooting.

A weak pump will not make the specified pressure, and show up as poor performance, and you will need a pressure and flow gage and shut off valve to test it, as in wdchyd's video.

Valves don't appear to give to much trouble. The rate of leakage is determined by the factory. So many drops per minute.

Each 100 psi of pressure equals about 315 lbs.

 

[jinman]

Of course if you have plenty of money, time and live on the dark side of the moon this wouldn't matter right..??

:laughing::laughing::laughing: Couldn't you have managed to get pigs on the wing in there somewhere? I think his troubleshooting is hitting the wall.

Pfloyd, you either have some kind of leakage or extreme restriction causing the pressure to never build. You also have two big users of hydraulics that you can use to help isolate the problem. The first thing I would do is remove the loader from the equation by disconnecting the quick connects on the right side (all 4 of them) and see if that changes the pressure. If it doesn't change anything, hook the loader QCs back up.

Next, I'd disconnect the hydraulics going to the backhoe and put everything back to normal (leaving backhoe attached but just disconnected from the hydraulics). Use the loader to check for normal operation. If the loader works normally with the backhoe disconnected, you really need to check the pressure at the diverter coming down from the joystick valve.

Here is what I think may be your problem. It's a guess, but it could sure cause exactly your symptoms. In the photo and illustration below, the joystick valve is shown. There is a plug inside this valve that can work loose and cause loss of hydraulic pressure to the rest of the system. When this happens, the loader seems to work normally, but nothing else will work right. Your 3PH, backhoe, or anything attached to remote hydraulics would not get full pressure and flow. It's such a simple thing to check that I would suggest checking before you go to a much more difficult and $expensive$ check.

So try to isolate the potential problem by removing the loader and then the backhoe. If that doesn't show improvement, then take off the cover on the joystick "power beyond" plug and see if it is loose and allowing fluid to bypass your backhoe and return to the reservoir.

PS, I hope you aren't offended by us having some fun with your user name. I'd bet it's not the first time somebody gave you a little kidding about your name.

 

[wdchyd]

:laughing::laughing::laughing: Couldn't you have managed to get pigs on the wing in there somewhere? I think his troubleshooting is hitting the wall.



PS, I hope you aren't offended by us having some fun with your user name. I'd bet it's not the first time somebody gave you a little kidding about your name.

Hopefully your first name is not "Pink"......I didn't mean any bad about it also, just kidding around.....

Heck, I've had people think I was the "Wild Child".....Far from it.....:laughing:

 

[J_J]

arljbuilding

If your pump is good, and you activate a good valve, and the fluid is going to the cyl, then the pressure will build until the relief, relieves, and that will be at some high pressure. If you can't build pressure no more than 500 psi, the pump is degraded from it's normal 2500 to 3000 psi.

Are all the hoses connected correctly.

As soon as you activate the first spool in the series valves, the fluid is redirected to the cyl in the FEL.

What is the pressure with all the levers in neutral? Should be 0 to very low.

Have you did a pressure check on anything?

I am not so sure we have the complete story.


The PB set screw , if loose or out, will only affect flow after the FEL. FEL should still work.

He said he has a new pump.

Purchase a hyd gage and track down the pressure and flow.

That valve that you tightened in the back, was that the 3pt fall adjustment? I believe there is a ball and spring inside the unit to control the flow out of the cyl. All the way tight, the 3pt stays locked up.

Recheck all the QD's. You can feel the line that have pressure when you activate a spool.