446 has no hydraulics!

[metalguy]

My 1974 446 has got me baffled. I have used this tractor for 4 years, and have had few real problems, but this has me stumped. I drove it onto the tractor lift for maintenence, and before I did any work to it, when I started it back up to move it a bit forward, it wouldn't move...at all! So I tried the lift lever for the deck, and nothing. My heart dropped, as I am thinking the pump went out. I looked, and plenty of oil in the tank, lovejoy spinning, etc. Drive handle in low, etc. So.... I bought, and changed the pump (After removing engine, and everything in the way) I put on the lovejoy, with new spider joiner, and after filling the oil, gave the starter a spin....and still no hydraulics. Only thing I can think of is it is bypassing completely through the travel control?? I have zero hydraulics. Any ideas, guys? I have swapped the pump on my 1974 646, so it isn't like this is new to me, but I am pretty flustered with this one.-------Metalguy

[Spike188]

@metalguy I feel your pain. Last week a neighbor called for help. His sawmill powered by a 40 hp Kubota would not start after he serviced it. During the drive to hos place, a mental check lost and wiring layout was thought through. On my arrival, he wasn't in the shed, I turned the ignition switch, nothing happened not even a click. Checking the battery voltage returned a reading of just over 10 volt. A short time on jumper cables and the engine started. His system had an electrical cutout when the voltage dropped below a certain point.

My first thought about your tractor was, "the high/low gear selector is in neutral. Buy reading on you have no deck movement with indicates no hydraulic pressure.

I rule out control issues because the lift control and forward reverse systems are separate. I am falling asleep while mid typing. Maybe I will dream up answer tonight and have a suggestion in the morning.

[Eugen]

It's hard to have an opinion without more detailed troubleshooting info. Like, here are some questions/suggestions that come to mind
1 you said you gave the starter a spin. What happens if you run the engine for a minute, while moving the lever(s) so you chase any air out of the system?
2 is the pump shaft moving for sure?
3 did you try to see if you got oil returning to the tank? Either by removing the return hose from the tank, or by peeping inside the tank.
4 are the tcv spools moving when you actuate the levers?

I guess it would be possible for the TCV to have some sort of an internal failure but I can't think of a way to test without replacing it. Seems very unlikely, but still possible.

[propane1]

My guess is, the line from the reservoir tank to the pump is blocked some how.

Noel

[Spike188]

I did not wake up with a solution. Eugen and Noel both have valid points. I have dealt with collapsing hoses in the past, and jave learned to look for sympoms cuased by one. They will sometimes look and function ok until a demand for full flow is encountered. An example would be looks good at idle speed but collapses at full throttle.
When the oil is flowing properly, turbulence can be observed in the tank.

As an engineer service tec said years age. Let's not make this complicated by over thinking it. Check off the simple stuff first. Is the final drive in low range. Jack up the rear of the tractor and make it stable. Start the motor and move the speed control. Did the wheels turn at all, even a little bit?

[Spike188]

Another thought is some hydraulic pumps can be configured so that the inlet and outlet ports are switchable. This involves taking the pump apart to reconfigure the input shaft position.

[DavidBarkey]

My 1974 446 has got me baffled. I have used this tractor for 4 years, and have had few real problems, but this has me stumped. I drove it onto the tractor lift for maintenence, and before I did any work to it, when I started it back up to move it a bit forward, it wouldn't move...at all! So I tried the lift lever for the deck, and nothing. My heart dropped, as I am thinking the pump went out. I looked, and plenty of oil in the tank, lovejoy spinning, etc. Drive handle in low, etc. So.... I bought, and changed the pump (After removing engine, and everything in the way) I put on the lovejoy, with new spider joiner, and after filling the oil, gave the starter a spin....and still no hydraulics. Only thing I can think of is it is bypassing completely through the travel control?? I have zero hydraulics. Any ideas, guys? I have swapped the pump on my 1974 646, so it isn't like this is new to me, but I am pretty flustered with this one.-------Metalguy

First thing first . Did you try the lift cylinder at all to validate "no hydra" ? Second, are you 100 % sure your new pump is not the wrong direction . There are CKW and CCKW pumps .
Pumps don't just stop pumping , they loose pressure and volume . Unless there is a drive failure like a key or seal failure .
Is there any squeeling from the hydra on use.
Try rolling the tractor with the trans in low and the engine off and the travell selector handle in neutral. See if there is resistance from the hydradalic drive motor like when it over run on a hill .

[Eugen]

Lots of good suggestions. I'm thinking though that reversing the in/out of the pump is not easy on Case tractors because the inlet is usually a different size and more over, straight pipe coming out of the pump with 3/4 suction hose on it. One needs to modify the original setup quite a lot to reverse it.

Anyway, at this point step by step careful troubleshooting is what's needed.

[metalguy]

Wow, guys, thanks for the replies. Ok, when running, there is no movement when in gear (low range), and the lift will not move at all. When the pump on my 646 died, it just lost more and more pressure until it would barely move, but the three point would still go up and dow, just not much force. The pump I have in it is the correct drive direction, and even has a little arrow showing direction that is correct. I will check for turbulence in the tank whiloe running, great idea! If there is some kind of air bubble, preventing flow/pressure, how would I relieve it? The suction line to the pump is new, and not collapsed. Does the pump need to be primed? Never had to do that. The pump itself is from Surplus supply, same type I put on the 646, with a lesser, and more appropriate volume. I'll try and get on it this weekend, and see how it goes. Please keep the inquiries/suggestions coming. I just know it has to be something very simple, just don't know what it is. I'll keep digging until I get it figured! -------Metalguy

[Eugen]

Oh, so you didn't install a used original pump. The most important troubleshooting step now is to make sure you got oil coming back into the tank.

If the pump doesn't push oil either the gears are reversed, or it's broken, or it has no oil coming to it. Most new pumps are reversible flow by reconfiguring the internal gears. Can you point to the pump you got from surplus?


Here's an excerpt from a regular hydro pump we can get here at the local store, as an example how it can be reversed.