NT-254 hydraulic pressure question

When you say “stalls out” do you mean the engine stalls, or the relief valve opens (hissing noise)?

In either case it sounds like your relief valve is not working. It should be more like 2000 PSI.

What FEL do you have?

Which FEL control valve?

RonJ

   I have a 2008 NT254 with the NT700 loader as well. If yours is like mine then it has a set of Cross SS series FEL control valves with a non-adjustable relief valve that was supposed to be designed for 2600PSI. I did not have any problems with mine opening at such a low perssure, but I replaced it after a year or 2 for other reasons.

smokey44 wrote:

My loader functions seem a little slow, especially the bucket in the dump function.

You will have to get a valve that has a regeneration spool detent (regen) that allows the oil to take a shortcut. Cross, Vickers, Prince, et al make a real loader valve with regen and float functions. Surplus Center is currently out of stock, that's where I bought mine

“My 3 pt also reliefs at 1300 psi. but is not slow.”

This just makes me suspicious. There isn't any connection between the 3pt valve and the loader valve. It may be coincidence, but it's strange that they're both relieving at low pressure, and at the same pressure. It's enough to make me wonder if maybe the valves aren't really relieving, but the pump is having trouble making pressure. When a cylinder reaches the end of its travel, there should be audible hissing, and it should be coming from the valve controlling that cylinder. Is that what you're hearing?

I'm not saying necessarily the pump is bad, it could be a clogged filter, low hydraulic fluid, air in the system, something like that. These pumps don't like to have restriction on the intake.

That said, 200 hours is plenty of time for a pump to fail.

There is no “system” relief valve. Each valve has its own relief — the loader, power steering, and 3-point hitch.

How is your system plumbed? Mine it goes from pump to loader to steering to 3-point, so “right before it enters the loader control valves” is the output to the pump. The output to my pump is a hose about ten inches long with a quick-release on it and the loader is connected using the quick-release so it can be removed from the tractor.

If your system goes pump to steering to loader to hitch, problems with the steering valve could cause problems for everything downstream. There is a pipe on the steering valve that goes back to the hydraulic tank. If the steering is using hydraulic power it sends the fluid it uses back to the tank and bypasses everything downstream of it. If that valve were leaking internally there would be no power downstream.  The valve I'm talking about is bolted to the side of the engine by your right foot, it has five hoses or pipes connected to it — send and receive from the steering wheel, power in, return to tank, and power beyond (downstream).

I'm just thinking out load. I don't know how to diagnose the steering valve.

quicksandfarmer wrote:

“There is no “system” relief valve. Each valve has its own relief — the loader, power steering, and 3-point hitch.”

I think you might have them confused with load check valves, which, quite frankly, I'd be surprised to see on these tractors. I doubt if there is three or more separate relief valves. One is all that is needed, or one per pump.

All I know is either the 800 lbs. the Chinese ZL20 loader is rated at is more than the tractor can handle or it lifts a lot more than 800 lbs. I attempted to move a pallet with 1/2 cord of truss scraps on it. It lifted it just fine, but flattened the two front tires and lifted the rear off the ground even with a box scraper back there.

do you have your tires inflated to the pressure needed for the weight of a loader and load.and are the tires the right ones to carry that load?I would think that they need to operate at least 60 psi.I know that this is not your primary issue,but…..and it might be a good idea to add more weight to that box blade,I have used two 40 kilo counterweights straped to mine,sure does make it work better too.

If your pressure gauge is in between the Hydraulic pump outlet and the inlet to the loader valve, your outlet pressure should be around 2,300PSI, the relief valve on the loader may be set at a lower pressure but this is the pressure you should have on your gauge.

If your pump is only producing 1300 PSI at its outlet, everything else will have that same pressure or less

Tommy

Affordable Tractor Sales

“Your Jinma Parts Superstore”

http://www.affordabletractorsalesco.com

Smoky,

1. Is your pressure gauge installed on the line that goes from the pump directly into the loader control valve?

2. If you can tell us what brand that loader control valve is – someone can probably tell whether and where the relief valve is on that valve.  (or can you post a picture?)

RonJ

Smokey —

I think you're on the right track trying to bypass the diverter valve, if it were leaking you would see low pressure on everything downstream. The bad news is, on my tractor at least, the fittings on the diverter are oddball metric fittings that I've been unable to find a source for.

I have an idea for you. Is your loader connected with quick-disconnects so you can remove it?  On my tractor the plumbing goes pump — FEL — Diverter — 3PH. So the output of the pump is a short hydraulic hose with a quick-disconnect on the other end. What you want to work toward is a similar setup, so your plumbing goes pump — FEL — 3PH with the diverter valve out of the picture. The pump-FEL connection is going to be through quick-disconnects.

If the short hose that goes from the pump to the diverter on your tractor is the same hose I have, then you should be able to disconnect one end from the diverter and put a quick-disconnect on it, attach that to the input of the FEL and you're all set. If it's an oddball fitting that you can't match, what you need to do is get a hose like the one I have which will take a quick-disconnect. Your best bet then is to talk to one of the dealers like Tommy at Affordable.

One of the things about Chinese tractors is they seem to build them with whatever parts they've got lying around on the that day, so the fact that two tractors are the same model or year doesn't necessarily tell you much. The parts book that came with my tractor lists four possible layouts for the hydraulics. However, the hydraulic pumps seem to be highly standardized, and the output is just a simple banjo fitting. So I think there is a very good chance you can get a hose with a banjo on one side and a quick-disconnect on the other.

Smokey,

Here is a picture of my hydraulic hoses/flow. I know that it is not the same as yours, but perhaps we can use it for discussion.

The output hose (A) from your pump needs to feed the input port of the FEL control valve. That is where the Pressure Gauge should be attached.

Let's look at the FEL valve. Ignore the hoses that feed the FEL cylinders and you should have 2 hoses left. One is the input (for hose A) and the other ouput. Let's consider the hose out of that output as hose B. It needs to go into the input port of the Diverter Valve as shown in the 3^rd picture. (While you are looking at the FEL valve, check to see if there are any “unused” ports that don't have hoses plugged into them. If there are, let us know.)

This should get us started talking.

Does your Diverter valve look like mine? You said that the FEL valve is presently fed out of the left side of the Diverter. Is that where mine shows line D? Where does your 3pt system get fluid from?

RonJ

I have seen a number of Nortrac machines hooked up this way.  It is wrong.  Pressure from the pump should feed the FEL valve then from the FEL to the flow divider valve.   Once you get it switched around you should see an improvement. 

Smokey, I have to take something back that I said earlier. I must have been looking at specs I saved on a set of Cross valves that I was considering purchasing as a replacement for the stock valves on my NT254. I found notes on my original set that states the pressure relief valve is fixed at 1300PSI, not 2600. That explains your 1300 PSI peak.

   My NT254 was plumbed originally with the pump feeding the diverter valve. The diverter split the flow to the power steering on one side and the FEL + 3PH on the other. The fluid to the 3PH goes through the FEL valves and out of the power beyond port of the FEL valves to feed the 3PH, so anything we do in the FEL or 3PH circuits will be limited by the relief valve on the FEL. I also found the FEL to be annoyingly slow, it only gets half of the fluid from the pump so it may still be able to get pressure to lift but the fluid flow rate stinks so it is slow. I replaced my 7GPM Cross valves, with 1300PSI relief valve, with a set of 10GPM valves from Surplus Center, with 2000PSI relief, and moved them upstream between the pump and diverter valve. The FEL movement speed about doubled and I am very pleased! There is one quirk however to having the FEL valves upstream of, and in line with, everything else. If the FEL is in the float position, and you turn the wheels developing pressure in the system via the power steering, or you raise the 3PH with a load on it again developing pressure in the system, the FEL will raise! Someone here can probably explain why. Something to do with the float position ties all ports together and then to the power beyond port, and if pressure developes downstream it translates back upstream to the FEL cylinders?? A small price to pay for the increased performance of the FEL though. About the only time it has really annoyed me is if I have the FEL bucket floating on the ground moving forward to scrape up a bucket of stuff, if I try to correct my heading by using the steering the FEL raises up and I don't get a clean scrape off the ground.

Dug around a bit and found my original Cross FEL valves. Relief setting is even stamped right on the valve!

Smokey, correct. the upper front hose is a 'return to tank', I think the casing next to it is even stamped with a “T”. The 'other return hose' on the back of the FEL valves, that is the Power Beyond port of the FEL valves, goes to what looks like a tank return on the right side of the hydraulic sump, but that is actually the input port for the 3PH. Looks like our machines were identical.

Other experts correct me if I am wrong, but we have to be carefull what we plug! These are 'open center' hydraulic systems. All fluid flows through things, not past them. Even when a valve is not being used to move something, the fluid coming into the valve or set of valves has to have an open path through the valve(s) to something else and eventually the tank. Fluid flows through the FEL valves, out of the power beyond port even when the FEL is not moving, down to the 3PH, through the 3PH hydraulics that are built into the hydraulic sump casing, and then out of the 3PH hydraulics into the sump. If you remove the FEL then, yes you are correct you need to take the hose that used to go from diverter to FEL and connect it to the hose that used to go from FEL power beyond to 3PH. Failure to do so would create a dead end for fluid on that side of the diverter, a 'dead head' situation. I don't know enough about diverters to know if a dead end on one side of it would 'dead head' the pump and blow it up or not but I wouldn't want to try it! I tell you what I did though when I started playing with my hydraulics, to protect myself from any possible situation the first thing I did was to install a stand-alone pressure relief valve as the very first thing on the output of my pump. I am bulletproof! No matter what I do, except for maybe completely plugging the return line to the tank, I cannot dead head my pump.

    Anyway, getting back to the FEL valve plumbing, I think you also need to leave that as it is as long as you are using the Cross valve set. You have to have the power beyond port feed the 3PH. When FEL valves are not activated, all fluid to the 3PH still has to go through the valves, through the PB port, and to the 3PH. You also need the return to tank line from the FEL valves. When you activate a FEL valve, all fluid that used to go to the 3PH gets routed to a FEL cylinder. The cylinder moves and the fluid returning from the other end of the cylinder doesn't go to the power beyond port, it goes to the return to tank instead, I think. That being said however, I have evidence to the contrary. I bought a new set of FEL valves with PB port and put them right in place of the Cross valves. Everything worked but the FEL was still slow. Then I moved them upstream of the diverter valve, removed the power beyond port insert and replaced it with a plug made specially for that valve set, and ALL hydraulic fluid for my tractor now runs into the new FEL valves, out of the return to tank port, and then to the diverter valve. I don't know if those 2 configurations are basically an industry standard or not. If so then you could probably do teh same with the Cross valves. Bob Rooks really knows his stuff. He and probably some others here could either confirm or dispute that idea.   

Cool! To be completely honest I liked the Cross valves better than the Brand Hydraulics set that I replaced them with. The Cross valves would let me activate both raise and curl at the same time. I can't do that with my current set, at least not the way I have them plumbed. I was using the PB port when I had the Cross set, and I am just using the tank return on my new ones now. Responding to your posts made me think this out and I am now considering re-plumbing my current set to use the PB port to see if that is what caused it. 

Smokey,

I would like to help, but I am still waiting for a response to the questions that I asked back in note #21.

RonJ

Smokey,

Thank you for the response. I will study this and get back to you this evening.

I download pictures this way:

Left-click on picture to open it up.

Right-click on picture should bring up a 'menu'.

Pick “Save Image As …” should bring up the 'save location' box.

I save it in my Pictures folder.

Then open the Pictures folder and Double-click on the file that you just saved.

That should open the file in whatever application your computer uses for JPEG images.

Go to the Edit menu to select the Print option.

RonJ

Smokey,

Click on my icon at the upper left of this message.  That will bring up my Profile.  Send me your Email address and I will send you some information that may help to understand the functioning of a FEL control valve.

RonJ

Smokey,

   You are feeding the diverter valve from the tank return line of your FEL valves. Since you are utilizing the power beyond port on your FEL valves, all excess fluid goes there instead of to tank. You won't get anything to the tank return port on the FEL valves unless you are actually moving the FEL. That is why you don't have any fluid for your power steering. You basically bypassed the diverter valve and PS by going straight from FEL Power Beyond to 3PH.

   You should run your FEL valve tank return line to the steel return line on the left side of the tractor, or just use the original FEL return to tank line. Your FEL Power Beyond port should go to the input port #1 of the diverter valve. Your mystery hose, diverter valve Port #4, should feed the 3PH.

   Or look at it this way : Put everything back the way it was originally. Then pretend you are removing the FEL by taking the quick coupler hoses that went from diverter to FEL valves, and from FEL valve to 3PH, and couple them together. You now have fully operational PS and 3PH, but no FEL. Now interrupt the line from pump to diverter valve and insert your FEL valves there by running pump to FEL valve input and FEL PBY port to diverter valve.

Smokey,

I agree with Grumpy.

Just to be sure let us walk through the connections using the picture that I posted in #21.

Line A goes from the pump output in photo 1 to FEL valve input in photo 2. At point A in photo 2 is where your pressure gauge should be installed.

Line B represents your Power Beyond output from the FEL valve and should go to point B input in photo 3.

I would set it up so that the 3pt is fed from the Diverter valve as shown by D in photos 3 and 6. This will let the Diverter Valve do what was intended.

Finally, I would figure out how to get that remaining hose on the FEL valve (which is now simply a tank return hose since the Power Beyond is used) connected to Z shown in photos 3, 4, and 7.

RonJ

Smokey, glad to be of assistance, especially to someone with a machine exactly like mine. I'm no expert on tractors and hydraulics in general but I love my NT254, it has been very good to me, and I'm glad to see others like it out there. Now that you've got the hydraulics straight I am going to admit to something that may sound a bit odd. It is really fun to move dirt around with the FEL valves upstream of the diverter. Then I ran into a case where I wanted to carefully manipulate a BIG rock, and another where I wanted to lift and carry something rather large that stuck 8 feet out in front of the bucket, and I needed slow instead of fast! I actually bought a flow control valve and installed it in parrallel with the FEL valves. It is a bypass around the FEL valves. With flow set to 0 the FEL moves at full speed. By allowing some flow to bypass the FEL valves however I can slow down the FEL for greater control. Crude I guess, but effective!

These are very simple but people like NT can make it a big mess. We used to do warranty work for them. The number 1 customer complaint was slow loader with no lifting power. First the mystery valve. It is called many names even within the industry. A diverter valve, well maybe. A flow divider? A tee would divide the flow why don't they just use that instead? Really the correct name is a hydraulic priority valve. What it does is it give hydraulic priority to the steering over the 3 point.

When the tractors come in and are removed from the crate of course there is no loader. The fluid (pressure side from the pump) is plumbed into the front of the priority valve. Next step is to install the loader. Simple and best way to do it is feed the IN side of the loader valve directly from the pump. The OUT side from the loader valve then goes to the front of the priority valve where the pump pressure used to be connected. Ten minute plumping job and we are done. Now the loader valve not the priority valve determines system bypass pressure.

I have seen them plumed two ways from NT. One way the way we do it and the other is the way you guys have described it. The second way gives much slower response from the loader and it has less lifting capacity. This keeps people from tearing things up which is their goal.

There's my $0.02 and too many decades of fighting with this stuff. 

Larry

The earlier models only had one line to the rear.  This worked ok for things that required HYD pressure to raise and gravity to fall.  Things such as a dump trailer or plow would work with this.  On later models they had a steel return line that went directly into the 3 point lift housing sump.  The knob in front of the seat has a couple of functions.   You could adjust how fast the 3 point would fall based on how heavy of an attachment you had.  The further clockwise you turned it the slower the 3 point would fall.  There is a set screw in it so be sure you loosen that first.  When the knob is turned all the way in the oil is routed from the three point to the HYD line on the back.  Pull the 3 point handle back to send pressure (oil) out the line.  Push it forward to allow the oil to flow back in.