TC40 DA FEL Pressure

[djaustin]

My son experienced a casuality on my 05 TC40 DA. < 500 hrs. While pushing a stump, the left lift arm cylinder hose burst. ( 3/8" 3000 PSI) He replaced the hose and continued without incident for aprox 15 minutes, then lost all hydraulics to the FEL and rear remote. Tractor drove fine however. Then he called me- I found a low hydraulic fluid level. (loose fitting allowing the hydraulic fluid to drip slowly out) Refilled but bucket would not lift. Finally with high RPM, bucket began shaking and slowly lifting. Topped of hydraulic sump to proper level again. Finally bucket came up, and held. Bucket tilted fore and aft fine, but raising was still a little shakey. Raised up and down several times to bleed air from system as per NH manual. Parked tractor in shed. Next day, had the same symptoms when raising the bucket, and bucket would drift down fairly quickly. Sump level is correct, I checked the slotted plug on the control block underneath the right side of the tractor, and it was in the correct position to allow flow to FEL remote and then to rear remote. Hydraulic pump visually looks fine, but somewhere there is a noise I never hoad when accuating the FEL control valve. (tinny, ratteling noise, air still in system maybe? ) Any Ideas anyone? Thanks

 

[jinman]

When your son replaced the busted hose, did he use teflon tape on the fitting? If he somehow managed to get teflon tape loose in the system, that may be lodged somewhere causing problems. That scenario would account for the tractor acting normal for a few minutes before the tape piece found its way into the joystick control valve. If it wasn't tape, it might be some other foreign material.

Does the 3PH work normally? If it works fine and has full power and speed, then the problem is isolated to the FEL or remotes. I would not continue to try and use the FEL. If the foreign material gets into the main system, it could take out the hydraulic pump or even the HST transmission. I don't want to be an alarmist, but you need to proceed carefully and consider what could be about to happen.

Of course, I don't know if it is what I suspect. But if it is, it could be costly.

BTW: I have hit stumps and done exactly as your son did. I've busted all four curl circuit hoses on my tractor and replaced them. Because the hoses/cylinders are completely isolated from the hydraulic system when the joystick is centered, it's not likely that the extreme pressure could have caused a system hydraulic overpressure. However, it could have blown out a piece of a cylinder seal and that could go unseen until you experience problems. That's also a possibility.

 

[djaustin]

Thanks Jim,
He did not use teflon tape, but I agree forgien matter is the number 1 killer of hydraulic system components. I will be in the garage tonight and probally all weekend testing and troubleshooting. I was hoping for a an - oh yea that happened me and the fix was simple- answer, but like you stated this could be costly. I'll post what I find.
Thanks again.

 

[jinman]

Be sure to check and reseat the quick-connects going to the loader. Your symptoms don't sound like that problem, but it wouldn't hurt to check.

BTW: How do you know the rear remote is not working? Do you have something attached to it/them?

 

[djaustin]

My rear remote is working, I tested it out last night as the backhoe was attached. I found massive air bubbles in the FEL lift arm cylinders when I loosened the connections. I bled both sides of the cylinders, and the spool valve connections at the joy stick. The spool valve connection bleeding had the greatest effect. Operation is 90% better. Hopefully operation this afternoon will still be the same, requiring only a little more operation and system bleeding. If it is worse I fear I am sucking air into the system somehow, or perhaps the pump is churning the oil and aerating it. I think the pump is a positive displacement gear pump, and hope it is not damaged. I will trace out the suction lines back from the pump and tighten the connections. I need to find how the system is vented, I only know of the vent at the sump fill so far. This may be the only one. Does anyone know if a factory service manual is available?

 

[jinman]

That's good to know that your rear remote is working. That means the system and pump are probably okay. I can't imagine why or how you got so much air into the system. As I mentioned earlier, I have blown all four of the short curl cylinder hoses and replaced them. All I ever did was to cycle the bucket and return to work after a replacement. I've never had any more problems. You might try swapping your curl and lift circuits at the quick connect fittings beside your right loader post. That would help identify a problem as being in the joystick control or the lift cylinders.

I think there is only one vent, and it is on the main reservoir.

You can order a repair manual from New Holland's website. Here is a link:

Tech Pubs

Enter the tractor (TC45) and choose "AG Repair Manuals" from the dropdown menu. Don't be too shocked when you see the CDs for $598 ea. Scroll down and you will see individual manuals for about $98 each. Click on the blue book outline to see the specific systems covered by each manual. Normally it takes three manuals to cover an entire tractor. As I remember, I paid almost $250 for a complete set. They are expensive, but worth it in my opinion. If you only want one that covers the hydraulic system, then you can get that for less than $100.

 

[djaustin]

Thanks again Jim, Repaired it two nights ago, when my parts came in. Didn't want to post again until I knew the problem for sure and had it fixed. The steel line from the filter outlet running underneath the tractor and ultimately to the pump, is segraterd into two seperate pipes, and connected together with a rubber boot and hose clamps. The pipe from the boot to the pump got bent (out of round) inside the boot and would not seal with the clamps. The pump was sucking in air. Replacing the pipe repaired the problem. It is strange I only had the problem when accuating the bucket lift circuit though.

 

[dynasim]

How did you diagnose that? That sort of problem is almost impossible to find, and your secret would be good to have for the mental toolbox. There is another thread that had the same sort of problem(a cracked line, I think), and it took the dealers a huge amount of effort to find a fix it.

Could the application only to the curl be caused by the recovery circuit special to that system?

Chris

 

[dynasim]

This is the link to the thread. It was on the HST side, though.


http://www.tractorbynet.com/forums/nh-owning-operating/91824-grinding-sound-dealer-says-normal-12.html#post1065044

 

[jinman]

The steel line from the filter outlet running underneath the tractor and ultimately to the pump, is segraterd into two seperate pipes, and connected together with a rubber boot and hose clamps. The pipe from the boot to the pump got bent (out of round) inside the boot and would not seal with the clamps. The pump was sucking in air. Replacing the pipe repaired the problem. It is strange I only had the problem when accuating the bucket lift circuit though.

The big steel pipe is the suction for both the main hydraulic pump and the HST transmission. Where it splits, it goes to the HST charge pump inlet as well as continuing up to the main pump. The charge pump sucks oil from the reservoir and supplies it to the HST under pressure so the HST will never starve or cavitate. If you were doing a lot of work where the HST pedal was fully depressed (like mowing in HI/Turtle or going down the road in HI/Rabbit) you might have seen some HST starvation. As it was, only the main hydraulic pump sucked air when you were moving the FEL and using all the flow it could supply. At least that's my theory and I'm stickin' to it.

Anyhow, I'm glad you found your problem. Brush and limbs can do an awful lot of damage to the underside equipment. I'm glad yours was fairly obvious and also fairly easy to repair.