Our HST has some problems

[Qapla]

We have a NH TC40D with a FEL and BH.

Using it today I found a new problem ... I was trying to dig out a stump and when I positioned the tractor I discovered that the FEL will no longer lift the front off the ground. Even using the "tilt", it would not lift the front off the ground - it used to.

Also, when I had to drive out into the field quite a distance, I used Range II like I usually do. When I started, I was in "turtle", then I hit the button for "rabbit" and the machine bogged and almost died.

Later, we had a hose break and, when we brought the tractor over to take the hose off, we checked the hydro fluid dipstick. It did not show - the tractor was running.

Should we check the fluid with the tractor running or off? Also, would low fluid cause these other problems?

 

[texasjohn]

First, get the fluid level right. I. assume you lost fluid from broken hose. I check fluid with engine off.

Then repeat tests. Low hyd pressure could cause problems noted. Low fluid can result in low pressure if low enough.

 

[jinman]

Yes, low fluid could cause the problems. You just don't know how low it is if the dipstick is dry. You at least want some fluid showing on the dipstick. With the tractor running, it should read about the same level as long as the tractor is parked level.

You could also have an air leak around the main hydraulic filter or that rubber "T" that is bolted on the big hydraulic suction line coming from the filter. That "T" splits between the HST and the Main pump. If it is leaking both transmission and main hydraulics will have air and be weak. The "T" is right under the right-side operator platform in clear view and easy to get knocked around by brush and debris. Did you notice any bubbles in the fluid?

EDIT: If you find no leaks, the next thing is getting a pressure gage on the hydraulics to see what pressure you are running at about 2000 rpm. Full main system pressure on your tractor is 2500 psi.

 

[Qapla]

Update ...

We got the broken backhoe line fixed and made sure the hydro fluid was "correct" ... at least we think it is correct - it shows between the two marks on the dip stick.

The tractor ran fine in turtle and rabbit and the backhoe works fine and dug out a pine stump.

The front bucket was able to pick the stump up out of the whole and carry it to a burn pile. I was also able to dig dirt needed to complete the filling of the hole.

However, there still is no real down pressure on the front bucket. It acts as if it is in "float" mode. This causes it to not make a suitable grade as it will not level the dirt properly. It also will not lift the front off the ground to allow us to take the tires off.

Any ideas??

 

[JerryK]

Might just have air in the cyl's/lines... Run the FEL thru all its motions a few times.... That might help..

 

[jinman]

You could have a leak in a cylinder internal seal. Roll your bucket to dump position with the cutting edge down. Disconnect your dump/curl quick connects. Push down with the loader arms while backing up. Keep downpressure on the bucket cutting edge. If the bucket curls level, it is leaking internally. If it partially curls and then holds, then the seals are good. Internal leaks/bypassing can show up in strange ways, but when you disconnect your quick connects, it isolates your loader from the rest of the hydraulics.

Of course, you won't know for sure about your power until you check those pressures at the quick-connects with a pressure gage. Your tractor should have 2500 psi easily at around 2000 rpm engine speed.

 

[Qapla]

Update and additional info:

Used the tractor today and tried some of the things recommended. Still have problems.

A little extra info that I didn't think of before because it didn't seem to fit this problem ... but, one never knows.

Before the problems with the FEL we were using the tractor to dig up a stump. The tractor was lifted up on the stabilizers and the front bucket. I was digging when the tractor suddenly died. My BIL commented that I must have run out of diesel. I said I had not and was about to climb back on the tractor to see what was wrong. Suddenly, boom (well, kinda') and steam started billowing from the "passenger" side of the tractor. When the steam settled, we found that a "freeze plug" had blown in the side of the block. We later learned that it was not a freeze plug but the drain valve for the engine and that this is a problem with the NH. We took the tractor to the shop and they installed a new drain valve and also fixed a problem we were having with the glow plug timer and a broken pin on the BH bucket.

After we got it back from the shop is when we discovered that the FEL would no longer lift the front off the ground.

Today, I tried lifting the arms up and down to full limits to see if there was any air trapped. I also did the same with the curl. The bucket curls just fine.

However, I did determine that it is the lift arms that are not allowing the tractor to lift. With the bucket sitting on the ground, if I begin curling the bucket down, instead of lifting the tractor, the lift cylinders will begin to extend.

Now, when I lift the bucket all the way up it will do this just fine. When I lower it, it comes about 1/3 of the way down then there is a small snapping sound, like when a relief valve gives and a "bounce" in the FEL, then it comes the rest of the way down.

It does this every time I lift it all the way up.

I also noticed that some of the time it seems to be moving slower then it should when moving forward in turtle or rabbit, but seems to move fine in reverse. It does not always seem to do this. However, a couple times when I was going forward in high range and hit the rabbit button, it bogged down considerably before gaining speed.

We do not have a gauge to check the pressure.

Is this something that could be caused from the problem with the drain valve? Could the shop have left something "undone" that could be causing this? Is this something we should be able to fix or do we need to take it back to the shop ($$$$$$$) ?

 

[Leejohn]

Quote-----However, I did determine that it is the lift arms that are not allowing the tractor to lift. With the bucket sitting on the ground, if I begin curling the bucket down, instead of lifting the tractor, the lift cylinders will begin to extend.

Now, when I lift the bucket all the way up it will do this just fine. When I lower it, it comes about 1/3 of the way down then there is a small snapping sound, like when a relief valve gives and a "bounce" in the FEL, then it comes the rest of the way down.

That sounds like the piston is loose on one of the cyls.

 

[jinman]

With your bucket flat, put it all the way down as far as you can go with the lift arms. Disconnect the lift arm quick connects (both lines). Now, curl the bucket lip down to dump while watching the lift arms. If the lift cylinders extend as you curl toward full dump, then one or both lift cylinders is leaking internally.

By disconnecting the quick connects when the arms are down, you remove the joystick and all plumbing from the circuit except for the two lift cylinders and piping/hoses. If you quick connects hold as they should, the only way your lift arms can raise up is an internal bypass in one of the lift cylinders. If the lift arms move a bit and then hold firm, that's normal, but if the lift arms keep extending, then you have an internal leak. If the cylinders are the problem, I would just go ahead and rebuild both cylinders so they both match.

EDIT: Except for the main hydraulic filter and a short run of suction piping, your HST has nothing in common with the FEL hydraulics. I want to concentrate on the FEL problem rather than try to deal with two separate issues. Once the FEL problem is isolated, I'll try to address your HST issue.

One thing for sure, nothing you've indicated about the engine drain tap or the glow plugs could have any effect on the hydraulic system.

 

[Qapla]

jinman ... next time I am where the tractor is I will try that and see what happens ... could be a few days.

 

[GManBart]

I know it sounds dumb, but don't forget to re-check, and top off the hydraulic fluid after refilling, and cycling the FEL/BH/etc. if it was so LS that it didn't show on the stick, it probably had to refill a bunch of lines.

What happens is that you refill the case, start the engine, the pump sends th fluid to fill he lines, and the case is low again.....easy to check, and free!

 

[dave1949]

For the snapping sound -- check that all of your FEL mounting bolts are tight. You might be hearing the FEL to frame movement. My TC used to make that kind of sound and I found two loose bolts. I think the sound is gone now.

Check all of your bolts anyways. They do loosen.

 

[Qapla]

I will definitely re-check the fluid level next time I am where the tractor is. Right now it is at my BIL's house and that is about 45 miles away.

I will also check the bolts, but the sound the FEL makes sounds hydraulic, not mechanical.

 

[Qapla]

UPDATE ...

OK, went to the tractor today. Checked fluid ... FULL. Checked bolts ... TIGHT.

I disconnected the lift arms with the quick disconnects and curled the bucket. It did not lift the tractor and the lift cylinders extended. Figured it must be the cylinders. Tried to plug the QD back in. One went right in and the other fought me for about 20 minutes before it just slide right in ... go figure.

I checked the lift arms to make sure they actually connected right and ... it works :cool2:

I mean ... IT WORKS - COMPLETELY!!!

The FEL will once again lift the tractor off the ground and allow grading/back blading like it used to. The noise it made when lifted all the way up and then lowered is also gone. Not sure what the problem was, but it worked all day for me.

Now, as for the HST problems, those we still have. Noticed today it did not seem to be running at "full speed" in low or high range, rabbit or turtle.

... Except for the main hydraulic filter and a short run of suction piping, your HST has nothing in common with the FEL hydraulics. I want to concentrate on the FEL problem rather than try to deal with two separate issues. Once the FEL problem is isolated, I'll try to address your HST issue...

So, now that the FEL is working, on to the HST.

As an aside, we are planning on replacing the filter on the tractor ... all of them ... since it has been a while since that was done. This will include an oil change for the engine and, if needed, a fluid change for the HST.

 

[jinman]

I'm thinking when your fluid gets hot, your FEL problems may return. Now, I'd also raise the FEL and then shut off the engine. If you have a load in the bucket, it would be better. See if and how long it takes for the FEL to drop from the raised position. If it holds or drops very slowly (a few inches over 15 to 20 minutes) your FEL is normal.

I think both the main hydraulic filter and the HST filter should be changed. Also, with the tractor running, squirt some oil around that rubber "T" in the line to see if it gets sucked in between the "T" and the pipe where it is clamped. You may have a little air leak there. I don't know how many hours you have on your hydraulic fluid, but NH suggests a change at 300 hours. I've looked at my oil and it is crystal clear at 300 hours so I let it go to 500. I do change filters regularly. The HST filter on the left side of the engine is the most important. If your FEL works fine, the main filter is probably okay, but you may want to change it just for 'insurance' that both are okay. I recommend using NH filters for both of these. NH filters are more expensive, but you always know you have a filter that is proper for your tractor. To me, that's worth the extra money. The big expense to operating a tractor is fuel anyhow. Compared to 20 gallons of fuel, the filters are cheap.

BTW: Your HST has test ports for pressure testing. They are under the seat where there is an access panel. Your dealer should have a full test set to check the bypass pressures on your HST. If they are at 5000 psi, then your HST should be healthy. To test the charge pump, they have to modify the assembly above the HST filter so an adapter can be added to check charge pump pressure. Both of those tests will probably be good things to have done at the dealer. By the time you buy all the fittings, gages, and hoses to do these tests, you'll have spent more than the dealer will charge to do the tests.

 

[Qapla]

I'm thinking when your fluid gets hot, your FEL problems may return...

After connecting the QD back up and the FEL working, I used the tractor for a few hours while I dug a large pine stump out of the ground using both the FEL and the BH. All continued to work the entire time. In fact, after getting the stump out, moved and the very large whole filled and smoothed, I used the FEL to lift the front while I changed the front tires. My FIL bought new ones and he and my BIL had them on the wrong sides :mur: They are on correctly now.

Thing is, I don't think the tractor will get much warmer and the FEL continued to work.

BTW - Were can I find the locations of all the filters on the TC40D?

 

[jinman]

It's starting to sound like your problem may have been in the quick-connects, but I've never heard of them making symptoms like you had. I'll just hope you continue to have good performance from your FEL.

Your main hydraulic filter is between your right rear wheel and the running gear. If you look up under the operator platform towards the rear, you can't miss it. It's very large. The HST filter is just in front of your brake pedals on the left side of the engine bell housing and below the starter motor. It's tucked away behind the FEL sub-frame on the left side. Getting it off is always a challenge. The engine oil filter is on the right side below your fuel filter and very close to the loader quick-connects. Of course, the air filters are in the round canister on the right side of the engine after you raise the hood.

 

[Qapla]

jinman,

Thanks for the filter locations. We did find filters in those locations but did not know which one was for what. We guessed that the big one was hydraulic.

The air filters are a bit obvious and those we had no problem with. When we pulled the outer filter it was quite dirty - the inner one is "new looking" and as clean as if it just came out of the box.

Guess we might want to check the fuel filter too, while we are doing filters.

 

[Qapla]

OK, finally got the tractor back home. We are planning on doing the hydraulic service sometime in May ... or June ...

Anyone know how much Hydro Fluid a TC40D with a FEL and BH takes?

 

[jinman]

OK, finally got the tractor back home. We are planning on doing the hydraulic service sometime in May ... or June ...

Anyone know how much Hydro Fluid a TC40D with a FEL and BH takes?

A normal drain and refill with both main and HST filters is about 8.5 gallons. The specs say the reservoir holds 10 gallons, but that includes lines, hydraulic cylinders, and the HST transmission. I've always been able to top off my reservoir with less than 10 gallons, but if you buy 10 gallons, you can use the leftover in the front axle housing and power steering system plus have some left for make-up fluid in the main reservoir. When refilling, use the dipstick often to ensure you don't overfill. If you overfill by a small amount, it's no problem, but I would not want an extra gallon in the reservoir. A quar/liter would not matter.