New Holland TC35D Hydraulics won't work

   / New Holland TC35D Hydraulics won't work
  • Thread Starter
#11  
Yes, when I take the top inlet pipe of I can see it turn.
 
   / New Holland TC35D Hydraulics won't work #12  
Bruce, I think you either have a non-working pump or something is wrong with the drive gear as JJ suggested. Is your power steering working normally? Since the HST is working normally, I have to say that your problem is not fluid delivery to the pump. It has to be that the pump is not drawing fluid. I'd be inclined to remove the inlet flange and see if the pump has any suction. However, when you remove the pipe from the top of the pump, it opens the suction line to the HST and it will draw a bunch of air in a hurry if you don't plug the line somehow.

I believe the pump can have the seals rebuilt with spares, but I don't think the internal parts are replaceable. If the problem is not seals, I think you are looking at buying a whole new pump. You might want to check with a hydraulic repair shop or your NH dealer's service manager. The seal kit is about $190 and the pump is around $770 for a complete pump. As far as I know, the KYB (Kayaba) pump is made specifically for New Holland and is not available anywhere else.
 
   / New Holland TC35D Hydraulics won't work
  • Thread Starter
#13  
How do I know if it has a suction? I know the pump is turning because I can see it.
 
   / New Holland TC35D Hydraulics won't work #14  
Loosen the rubber "T" on the side of the line going to the pump. Next, remove the bolts from the suction tube flange on the top of the pump and rotate it out and away from the pump. You'll now be able to look right into the suction port. At this point, if you start the engine, the HST will draw air from the disconnected flange, but if you don't run the engine long, it won't hurt the transmission. Start the engine and then use your hand over the pump inlet to see if it has suction. If you don't want to check with your hand, then put some oil on a flat piece of metal or something strong and see if it suctions down to the pump's inlet.

All tests in the Repair Manual are for pump pressure. I don't know of a single test for the suction side, so you'll be winging it. Without any numbers, there's no way to know for sure, but if you have significant suction at the pump, then it should draw from the reservoir. If you have a quart of fluid handy, maybe pour it into the pump as it is running and see how fast/if it pumps through. Remember, don't run too long because your HST charge pump is sucking air unless you block the flange opening of the pipe.

EDIT: You'll probably need something to block the air flow from the fan if you try to pour into the pump. Trying to pour from a bottle into the pump with the fan blowing the oil everywhere could cause a mess. A piece of cardboard should be sufficient.
 
   / New Holland TC35D Hydraulics won't work #15  
If the inlet to the pump is flooded, then loosen or remove the pump pressure hose off the FEL valve, and place in a bucket and start engine momentarily.. If no flow, then the pump is bad.
 
   / New Holland TC35D Hydraulics won't work
  • Thread Starter
#16  
Ok, I did what you said but I couldn't fit my hand in there, so I used a piece of plastic covered in oil. It definitely had a suction but I have no idea how much.
And when I poured some hyd oil into it it sucked it right. I was actually able to get the bucket to move by pouring a steady flow of oil into the inlet hole and then operating the joystick.
Could this mean fluid starvation?
The filter will be here Wed so I will let you know what that does then, unless you have any other suggestions.

Thanks
 
   / New Holland TC35D Hydraulics won't work #17  
I am not understanding something here. If there is a tee from the tank feeding the hydrostat pump, then there should be fluid at the other port of the tee feeding the implement pump.

If you remove the input hose off the pump, fluid from the tank should flow out, unless there is a blocked filter or crushed hose before the implement pump.

Re-check the hose going to the pump.
 
   / New Holland TC35D Hydraulics won't work
  • Thread Starter
#18  
The pipe coming from the tank comes out the bottom side of the tank, it then goes straight up a foot which is where the filter is, it then goes straight back down runs about 3 feet to the front of the tractor and then comes back up a foot to where the pump is. In the middle of this U is the rubber T.
Because the filter is above the level of the hyd oil, nothing will flow on its own after it, it has to be sucked.
This is why fluid will not just flow out of the T.
 
   / New Holland TC35D Hydraulics won't work #19  
Bruce, I think you should definitely check that filter. Perhaps the HST is drawing all available fluid and the main pump can't get a good prime to get started. What does your hydraulic fluid look like? Is is fairly clear or slightly yellow/amber similar to the color of beer? The fluid should be clear to slightly yellow and not contain a lot of particles. I think you may have an obstructed filter. Is it a New Holland filter? There's just no way to know for sure, but what you've said about the way your pump worked when you poured in oil has me thinking the filter just might be your problem. If it is, you are gonna kick yourself for not doing that first thing instead of all the disassembly and reassembly of your pump. I'd say to make sure the pipe from the "T" to the pump is not clogged. If the filter went bad and some filter material got into your system, it could have clogged the pipe. I don't think that's likely because surely the HST charge pump would also be full of garbage. I'm just really surprised that the HST worked fine while the main hydraulic system seems to be starved. I will be very surprised if the filter fixes this, but I've been surprised before.

EDIT: Here is a copy of your hydraulic system illustrated. In the illustration, the HST "T" is not shown. The "T" would be between the filter #3 and the pump #4. Perhaps this diagram might come in handy for you.

181403d1286373580-tc35d-pto-wont-engage-hydsys-tc45.jpg
 
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   / New Holland TC35D Hydraulics won't work
  • Thread Starter
#20  
Ok, I got the filter today, but it didn't do anything.

So I guess it must be the pump or the seals. Is there any way I can find out if it is the seals or the whole pump?
If I do have to replace the pump, is there a way I can get a refurbished one for cheaper?

Thanks for all your guys help.
 
 
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