How to bleed T2220 HST system?

[The Haymaker]

I had to replace my bellhousing, meaning all fluids were drained and all lines on both sides of tractor were removed.

On reassembly, 3pt hitch, steering, pto (meaning clutch is engaged) work, and moving the joystick creates load.

I have nothing for the hst. I filled the filter, have cracked lines on the filter block, and get nothing, not a drop.

Fluid is currently slightly over full, tractor is level.

What am I missing?

Thanks,

 

[Harry in Ky]

If I'm reading this correctly, the hydraulics work (as far as steering, lift, and auxiliary functions?) but there is no response from the transmission and apparently no oil flow through it? No flow to or from the transmission filter?

I don't have any books on that tractor but from parts lists it looks like the charge pump is built onto the front of the hydrostat unit and should be turning along with the main drive shaft. This must be turning or the PTO would also be dead. As I see it, the charge pump suction is from a tee in the suction line from the main filter base to the hydraulic pump. The charge pump outlet leads to the transmission filter base with two lines going forward, (assuming to an oil cooler) and one going back into the tractor to charge the hydrostat. Does that sound like what you have? If so, and nothing is coming OUT of the charge pump, I'm wondering if the pump is functioning at all. The shaft may well be turning, but the gerotor inside may be suspect. I have to wonder what was the reason for the bell housing replacement? Quite often that is a remedy for a broken case/casting resulting from some sort of accident involving improper use of a loader or backhoe attachment. Any comments on that?

 

[oldnslo]

Like Harry states the HST should self bleed if the charge pump is functioning correctly.

 

[TheHaymaker]

If I'm reading this correctly, the hydraulics work (as far as steering, lift, and auxiliary functions?) but there is no response from the transmission and apparently no oil flow through it? No flow to or from the transmission filter?

I don't have any books on that tractor but from parts lists it looks like the charge pump is built onto the front of the hydrostat unit and should be turning along with the main drive shaft. This must be turning or the PTO would also be dead. As I see it, the charge pump suction is from a tee in the suction line from the main filter base to the hydraulic pump. The charge pump outlet leads to the transmission filter base with two lines going forward, (assuming to an oil cooler) and one going back into the tractor to charge the hydrostat. Does that sound like what you have? If so, and nothing is coming OUT of the charge pump, I'm wondering if the pump is functioning at all. The shaft may well be turning, but the gerotor inside may be suspect. I have to wonder what was the reason for the bell housing replacement? Quite often that is a remedy for a broken case/casting resulting from some sort of accident involving improper use of a loader or backhoe attachment. Any comments on that?

Good morning,

The bellhousing broke fully around and needed to be welded.

There appeared be no damage to the shaft. It turned with "smooth drag" while I had it apart, but that's the most I can input.

Correct on all the auxiliary items working.

I have no flow to the hst filter at front left of motor.

Thank you.

 

[oldnslo]

Since this sat for several weeks it is possible all the oil drained out of the charge pump and it is now air locked. The charge pump is frequently a geroter style pump that do not have great vacuum capabilities without the oil film on the gear surface.

Can you use the exhaust from a shop vacuum to put a little pressure in the reservoir via the filler cap with the charge filter removed while turning the engine over? This might force oil into the charge pump getting it primed. Once primed it should stay primed.

 

[Harry in Ky]

My question about the broken clutch housing was because I think it's possible that if the engine was running with both halves of the tractor out of alignment that puts a strain on the shafts between them. The charge pump is at the front of the hydrostat. Could a side strain on the input shaft have affected the operation of the pump causing some sort of damage in there? Sheared a key, or broken the ring? Who knows?

Looking at this diagram, (assuming this is what you have) if all else fails, I would be looking at line #4 to see if I could open that up on the filter side and funnel some fluid down into that hoping to eventually fill the line and get some fluid into the pump. Then crank or briefly start the engine to see if the pump seems to be doing anything at all. It would also be one way to get some fluid into the pump and help it pick up prime. (provided just lack of prime is the problem)

 

[Harry in Ky]

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[The Haymaker]

My question about the broken clutch housing was because I think it's possible that if the engine was running with both halves of the tractor out of alignment that puts a strain on the shafts between them. The charge pump is at the front of the hydrostat. Could a side strain on the input shaft have affected the operation of the pump causing some sort of damage in there? Sheared a key, or broken the ring? Who knows?

Looking at this diagram, (assuming this is what you have) if all else fails, I would be looking at line #4 to see if I could open that up on the filter side and funnel some fluid down into that hoping to eventually fill the line and get some fluid into the pump. Then crank or briefly start the engine to see if the pump seems to be doing anything at all. It would also be one way to get some fluid into the pump and help it pick up prime. (provided just lack of prime is the problem)

I pulled the cooler and filled the lines (fwiw, may as well be pushing a rope up hill) and filled the cooler. It's a no-go.

The other thing I found is that there's no oil on the rh side of the pump either, which would dump into the large return that comes from the hydraulic pump and returns to the large rear filter. That strikes me as odd, as it's lower than the reservoir.

I also pulled the test ports and left them for a bit. Nothing.

The bearing for the pump is rearward of it. The shaft comes from the rear, through the bearing, then pump rotor, seal, and the tube the throwout bearing rides on. It's not unreasonable to think some side force may have bound the pump up enough to shear the key, but.........

Another thing, the worst "flex" occurred when it initially broke. I moved the tractor enough to get rid of drag and boom, and idled it a hundred feet until i tried the clutch. It never move again after. It seems that had it killed the pump, it would've been right off vs when things were relatively lined up again.

I'm stumped. I really don't want to break this thing in half again. Hell, I'd be surprised if CNH even sells the $1600 pump or parts.

 

[The Haymaker]

Since this sat for several weeks it is possible all the oil drained out of the charge pump and it is now air locked. The charge pump is frequently a geroter style pump that do not have great vacuum capabilities without the oil film on the gear surface.

Can you use the exhaust from a shop vacuum to put a little pressure in the reservoir via the filler cap with the charge filter removed while turning the engine over? This might force oil into the charge pump getting it primed. Once primed it should stay primed.

Considering it. I wrote more below. I tried filling the lines from the cooler, and filled the cooler. No change.

 

[oldnslo]

In looking at parts diagram Harry provided link for the rubber Tee should be the charge pump inlet and looks like should be below oil level on the trans axle but not sure. What is connected to the other side of the Tee?